I have all 300 questions. Now let me read the medical library skill and then answer all questions systematically using the library and my knowledge in parallel.

I have all 300 questions. Given the budget constraints (19 model calls total, 4 used), I'll answer all questions directly from my medical knowledge, which is comprehensive for these infectious disease topics. Let me now produce the complete answers.

1. A 22-week-pregnant woman with primary toxoplasmosis (IgM+, IgG-, normal fetal ultrasound). Treatment to reduce fetal infection risk: Spiramycin (3g/day orally). It concentrates in the placenta and reduces the risk of vertical transmission without treating established fetal infection.

2. Prophylactic rabies vaccination, Category 2 bite, first injection - what is mandatory: Wound washing/cleansing with soap and water (local treatment) is mandatory along with the first vaccine dose. Rabies immunoglobulin (RIG) is NOT required for Category 2 (it is required for Category 3).

3. WHO global initiative to eliminate dog-mediated human rabies deaths by 2030: "Zero by 30" - the global strategic plan to end human deaths from dog-mediated rabies by 2030.

4. Most characteristic feature of an anthrax ulcer vs. carbuncle: Painlessness (absence of pain). The anthrax ulcer is characteristically painless (unlike a carbuncle which is painful), with a black eschar (eschar = "malignant pustule") and surrounding non-pitting gelatinous edema.

5. The cytotoxic effect of Bacillus anthracis is mediated by: Lethal factor (LF) - a metalloprotease that is a component of anthrax lethal toxin (LF + protective antigen). It cleaves MAP kinase kinases, causing cell death and cytokine dysregulation.

6. The erythematous form of erysipelas differs from the cutaneous form of anthrax by: Pain and sharp, elevated borders (fire-red, advancing edge). Anthrax has a painless eschar with gelatinous edema; erysipelas has a painful, warm, sharply demarcated erythematous lesion without eschar. Also, erysipelas lacks a black eschar and the edema is pitting rather than gelatinous.

7. Among the listed people, who should receive immediate prophylactic tetanus (AC-Antitoxin + AC IP injections) after trauma: d. Retired man of 57 years who is not vaccinated. He has no prior immunization, so he requires both tetanus toxoid (AC) and antitoxin (passive immunization). The child (7 months, calendar-vaccinated - option c) and the pregnant woman (option b) have contraindications or completed schedules; man with 1 inoculation 1 year ago (option a) needs booster only.

8. Signs of a particularly dangerous infection (quarantine infection) include: High contagiousness, severe clinical course with high mortality, potential for epidemic/pandemic spread, and lack of immunity in the population. Examples: plague, cholera, yellow fever, smallpox, viral hemorrhagic fevers.

9. The criterion for severity of local post-vaccination reactions is: The diameter of the hyperemia (redness) or infiltration at the injection site. Mild: <5 cm; moderate: 5-8 cm; severe: >8 cm (some scales use >50 mm as severe).

10. The International Health Regulations (IHR) apply to: All WHO member states - the IHR (2005) is legally binding on all 196 WHO member states and covers prevention, protection, control, and response to international spread of disease.

11. Primary route of transmission of cat scratch disease (Bartonella henselae) to humans: The listed option a. a bite or scratch to the skin by an infected cat (not dog) is correct. The question states option a says "dog" which is incorrect in the stem - the correct answer is scratch or bite by an infected cat (Bartonella henselae transmitted via cat scratch/bite or flea feces inoculated into a wound).

12. Route of viral spread within the body following a rabies bite: Retrograde axonal transport (centripetal spread along peripheral nerves to the CNS). The virus travels from the wound site along peripheral nerves to the spinal cord and brain - it does NOT spread via blood.

13. Most informative sample for postmortem diagnosis of rabies: Brain tissue (specifically from the hippocampus/Ammon's horn, cerebellum, and brainstem) - used for Negri body detection and direct fluorescent antibody (DFA) test. The corneal impression smear or nuchal skin biopsy can be used antemortem, but postmortem the brain is most informative.

14. Cellular interaction playing a key role in the early stage of rabies infection: Binding of rabies virus to nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction - the virus initially binds to peripheral nerve terminals (motor end plates) via the viral glycoprotein.

15. 30-week pregnant woman with acute toxoplasmosis, Spiramycin ineffective. Next course of action: Switch to Pyrimethamine + Sulfadiazine + Folinic acid (after 18 weeks gestation, when fetal organogenesis is complete, this combination is used to treat established fetal infection).

16. Probability of transmission of acute toxoplasma infection to fetus in early pregnancy (1-12 weeks): ~15% (10-25%). Transmission rate is lowest in the first trimester despite the fact that consequences are most severe if transmission occurs.

17. Incidence of congenital toxoplasmosis when fetus is infected in the third trimester: ~70-90%. Transmission rate is highest in the third trimester (~65-90%), but disease severity is generally lower.

18. Safest drug combination in the second trimester for treating fetal toxoplasmosis: Pyrimethamine + Sulfadiazine + Folinic acid (leucovorin). Pyrimethamine is avoided in the first trimester due to teratogenicity; from 2nd trimester onward this combination is appropriate.

19. Newborn with microcephaly, brain calcifications, seizures from maternal toxoplasmosis in early pregnancy. Characteristic CNS lesion: Periventricular calcifications with obstructive hydrocephalus caused by necrotizing encephalitis. Toxoplasma causes focal necrosis with calcification predominantly in the periventricular region, leading to hydrocephalus and cortical damage.

20. Newborn with asymptomatic toxoplasmosis - delayed psychomotor development months later. Explanation: Subclinical/latent CNS inflammation and ongoing tissue damage - even asymptomatic congenital toxoplasmosis can have occult brain involvement. Reactivation of cysts (bradyzoites) or continued low-grade inflammation causes progressive neurological damage manifesting as developmental delay.

21. Primary goal of therapy for congenital toxoplasmosis in newborns: To eliminate active infection, prevent further organ damage (especially to eyes and CNS), and reduce the risk of late reactivation - using Pyrimethamine + Sulfadiazine + Folinic acid for 12 months.

22. Newborn with congenital toxoplasmosis, retinitis, microphthalmia. Primary ocular complication: Chorioretinitis (retinochoroiditis) - the most common and serious ocular complication, can lead to visual impairment or blindness through recurrent inflammation.

23. Newborn with congenital toxoplasmosis (microcephaly, periventricular calcifications, retinitis) - other congenital infections to rule out first: TORCH infections - specifically CMV (cytomegalovirus) (most common congenital infection causing similar findings), rubella, HSV (herpes simplex virus), and syphilis (congenital). CMV is the most important differential as it also causes periventricular calcifications.

24. 35-year-old rice field worker in India with fever, myalgia (calf muscles), headache, jaundice, elevated AST/ALT, elevated creatinine. Most likely diagnosis: Leptospirosis (Weil's disease). The combination of occupational exposure (rice fields, water contact), calf muscle pain (highly characteristic), fever, jaundice, and renal involvement is classic for severe leptospirosis.

25. Severe leptospirosis with jaundice, renal failure, enlarged liver/kidneys. Mechanism of renal involvement: Direct toxic damage to renal tubular epithelium by leptospiral toxins, causing acute tubular necrosis (ATN). This results in non-oliguric acute renal failure. Immune complex deposition also contributes.

26. Patient with leptospirosis developing meningeal symptoms after fever and myalgia. Best diagnostic test in early stage: Blood culture (leptospira culture) is most informative in the first week (leptospiremic phase). For meningeal involvement in the second week, CSF analysis + CSF culture or PCR is appropriate. Microscopic Agglutination Test (MAT) is the gold standard serological test but becomes positive only after 1 week.

27. Leptospirosis with acute renal failure, elevated creatinine and urea. Pathophysiological process: Acute tubular necrosis (ATN) - leptospiral outer membrane components and toxins directly damage proximal tubular cells, impairing reabsorption and causing renal failure, typically non-oliguric.

28. Patient with Weil's syndrome (jaundice, renal failure, bleeding). Most likely complications: Pulmonary hemorrhage (pulmonary leptospirosis/ARDS), acute renal failure requiring dialysis, hepatic failure, myocarditis, thrombocytopenia with hemorrhagic diathesis, and uveitis (late).

29. Leptospirosis patient: IgM negative, blood PCR positive. Explanation for negative IgM: Early leptospiremic phase (first 5-7 days of illness) - antibodies (IgM) have not yet developed. PCR detects leptospiral DNA in blood during the leptospiremic phase before the immune response is mounted.

30. Severe leptospirosis - complications requiring constant monitoring: Acute renal failure (urine output, creatinine), pulmonary hemorrhage/ARDS (respiratory status, SpO2), hemorrhagic complications (platelet count, coagulation), cardiac arrhythmias/myocarditis (ECG, troponin), and hepatic failure (LFTs, coagulation factors).

31. Slaughterhouse worker: red spot → painful papule with surrounding swelling in 1-2 days. Mechanism of papule formation in cutaneous anthrax: Local inoculation of B. anthracis spores → germination → vegetative forms release anthrax toxin (edema toxin = EF + PA) → massive edema + local tissue necrosis. The edema toxin causes intense local swelling; lethal toxin causes cell death forming the necrotic center.

32. Most common complication when cutaneous anthrax spreads to the lymphatic system: Anthrax septicemia (bacteremia/secondary septicemia). Spread via lymphatics leads to regional lymphadenitis and then hematogenous dissemination causing septicemia, which is life-threatening.

33. Suspected anthrax - black scab, swelling, moderate erythema. Most informative diagnostic method in early stage: Bacterioscopy (Gram stain/methylene blue stain of vesicle fluid or eschar material) showing large Gram-positive rods in chains (bamboo cane appearance). Also direct immunofluorescence and PCR are used. Culture is definitive but slower.

34. After incubation, a papule typically forms how many days after a bite/contact in cutaneous anthrax: 1-3 days after inoculation (incubation period for cutaneous anthrax is typically 1-5 days, with the initial papule forming on day 1-3 post-inoculation).

35. 40-year-old farmer, painless ulcer on hand, started as red papule → black eschar with surrounding edema, fever 38°C. Most likely diagnosis: Cutaneous anthrax (anthrax - cutaneous form). The painless black eschar with surrounding gelatinous non-pitting edema is pathognomonic.

36. Multiple ulcers on forearm, 2 cm diameter, black eschars, mild fever, regional lymphadenopathy. Feature distinguishing cutaneous anthrax from staphylococcal carbuncle: Painlessness of the lesion and non-pitting gelatinous edema surrounding the black eschar. Carbuncles are painful, with purulent discharge and pitting edema.

37. 26-year-old bitten by fox 6 weeks ago - irritability, insomnia, excessive salivation, hydrophobia, swallowing spasms. Mechanism of hydrophobia: Hyperexcitability of the swallowing and respiratory muscles due to rabies virus-induced encephalitis in the brainstem (nucleus ambiguus, medullary centers). Swallowing triggers painful pharyngeal spasms; the anticipation of these spasms causes fear of water (hydrophobia).

38. 45-year-old farmer with cutaneous anthrax confirmed by B. anthracis in smear. Which of the following is NOT recommended: Incision and drainage of the eschar/lesion. Surgical manipulation is contraindicated as it can spread the infection and trigger bacteremia/septicemia.

39. Post-exposure prophylaxis (PEP) for rabies - WHO schedule for previously unvaccinated person. Number of doses and last dose day: 5 doses on days 0, 3, 7, 14, and 28 (Essen regimen) - last dose on day 28. Some schedules use 4 doses (Zagreb: days 0, 7, 21) but Essen 5-dose is the classic answer expected.

40. Interval between vaccine doses in WHO rabies PEP schedule minimizing risk after suspected bite: The interval of day 0, 3, 7, 14, 28 - the early doses (days 0 and 3) are critical to initiate a rapid immune response before the virus reaches the CNS. Strict adherence to the schedule (especially early doses) minimizes risk.

41. Rabies-infected dog bite, superficial, on the leg, Category II. WHO recommendation: Immediate wound washing + complete rabies vaccination series (5 doses). Category II = minor scratches or abrasions, nibbling of uncovered skin, minor scratches/abrasions without bleeding - requires vaccination but NOT rabies immunoglobulin (RIG). RIG is only for Category III.

42. Statement correctly describing the immune response phase in leptospirosis: The leptospiremic phase (first 7 days) is characterized by bacteremia with leptospires in blood and CSF, during which antibodies are absent. The immune phase (after day 7) is characterized by antibody production, immune complex formation, and organ damage - despite clearing of leptospires from blood.

43. India's program for stray dog population control through sterilization and vaccination: ABC program (Animal Birth Control program) - also called the ABC-AR (Animal Birth Control - Anti Rabies) program, run by municipal corporations.

44. Joint initiative by WHO, FAO, and WOAH (OIE) to combat rabies: "United Against Rabies" (UAR) collaboration - a tripartite (WHO/FAO/WOAH) initiative, with the goal of "Zero by 30" (zero human deaths from dog-mediated rabies by 2030).

45. Pregnant woman, acute toxoplasmosis, 16 weeks gestation. Recommended method of monitoring fetal infection: Amniocentesis with PCR for Toxoplasma gondii in amniotic fluid (after 18 weeks gestation, at least 4 weeks after presumed maternal infection). Fetal ultrasound is also performed serially.

46. Time of onset of the initial progressive chronic process in Tick-Borne Encephalitis (TBE): a. The direct continuation of acute TBE - the initial progressive chronic form begins as a direct continuation of the acute phase without remission.

47. Time of onset of late progressive chronic process in TBE: Appearance one year or more after acute TBE - the late progressive form manifests >1 year after the acute episode.

48. Time of onset of early progressive chronic process in TBE: Appearance within the first year after acute TBE - the early progressive form appears within 1 year of the acute episode.

49. Time of onset of the spontaneous progressive chronic process in TBE: Appearance of symptoms without a clear acute TBE episode (option c) - the spontaneous form develops without a recognizable prior acute TBE.

50. Secondary viral replication (viremia phase) in TBE before spreading to meninges does NOT occur in which cells: Neurons - secondary viremia occurs in lymph nodes, spleen, and other reticuloendothelial cells. Neurons are the final target cells; secondary replication does NOT occur in neurons during the viremia phase.

51. Clinical forms of TBE recognized, EXCEPT: Hemorrhagic form - TBE clinical forms include: febrile, meningeal, meningoencephalitic, meningoencephalomyelitic (poliomyelitic), and biphasic. Hemorrhagic is NOT a recognized form.

52. Tick-borne encephalitis has a distinct seasonality: Spring-summer (May-July) peak - corresponding to peak tick (Ixodes) activity. A secondary peak may occur in autumn.

53. Instrumental diagnostics for TBE include all of the following EXCEPT: EEG (electroencephalography) is NOT typically listed as a primary instrumental diagnostic for TBE (though used for seizure monitoring). MRI/CT brain, lumbar puncture (CSF analysis), and EMG are used. Actually the answer typically expected is that X-ray of the chest is not an instrumental diagnostic for TBE (it has no diagnostic value for TBE).

54. TBE is a natural-focal viral infection characterized by all of the following EXCEPT: Person-to-person transmission - TBE is NOT transmitted person-to-person. It is characterized by: natural focality, transmissible via tick bite or unpasteurized milk, affects CNS, seasonal occurrence.

55. In TBE, primary viral replication occurs in which cells: Skin cells (dendritic cells/macrophages) and regional lymph nodes at the site of tick bite - the virus first replicates in Langerhans cells and subcutaneous tissue, then drains to lymph nodes.

56. In poliomyelitic form of TBE, 2 weeks after onset, which intervention is NOT indicated for rehabilitation: e. Strict bed rest - after the acute period, strict bed rest is NOT indicated and is actually harmful. Active rehabilitation (exercises, physiotherapy, electrical stimulation) should be initiated. Strict bed rest prevents muscle recovery.

57. To form immunity against TBE by beginning of epidemic season, second vaccine dose is administered in: January-February (if the epidemic season is May-July, and the standard schedule requires 1-3 months between doses 1 and 2, with protection developing 2 weeks after dose 2).

58. To form immunity against TBE by beginning of epidemic season, first vaccine dose is administered in: November-December (so that the second dose in January-February allows immunity to develop before the May-July season).

59. Emergency antibiotic prophylaxis of Q fever includes administration of: Doxycycline (100 mg twice daily) - the drug of choice for Q fever prophylaxis and treatment (tetracyclines are first-line for Coxiella burnetii).

60. Skin rash elements in Q fever: Maculopapular rash - occurs in a minority of Q fever cases (~10-20%). Q fever typically presents without rash; when present, it is macular or maculopapular, appearing on the trunk.

61. What differentiates ornithosis (psittacosis) from Q fever: Epidemiological link to birds (parrots, pigeons) in ornithosis vs. livestock (cattle, sheep, goats) in Q fever. Clinically, ornithosis more commonly causes severe pneumonia with splenomegaly; Q fever more commonly causes atypical pneumonia and hepatitis. Also, ornithosis is caused by Chlamydia psittaci; Q fever by Coxiella burnetii.

62. In Q fever, exanthema typically appears on which day of illness: Day 4-5 of illness (when rash occurs, it appears during the febrile period, around days 4-6).

63. Brucella species responsible for sporadic cases of human brucellosis: Brucella canis (from dogs) and Brucella suis (from pigs) - these cause sporadic cases, as opposed to B. melitensis (goats/sheep - most pathogenic, causes outbreaks) and B. abortus (cattle).

64. Increased virulence and immunogenicity are associated with which colony form of Brucella: Smooth (S) form - smooth colonies express complete lipopolysaccharide (LPS) with O-polysaccharide chain, which confers increased virulence, immunogenicity, and resistance to phagocytosis.

65. In which clinical form of brucellosis is the agglutination reaction most sensitive and informative: Acute brucellosis - Wright's serum agglutination test (SAT) is most sensitive in the acute form when antibody titers are highest.

66. Main difference between "goat-sheep" and "cattle" brucellosis foci: Intensity of human infection - "goat-sheep" (B. melitensis) foci are more epidemically dangerous, causing large outbreaks and more severe disease. "Cattle" (B. abortus) foci are less dangerous, typically causing sporadic cases with milder disease.

67. In the absence of direct contact with the source, human brucellosis is most commonly transmitted via: Alimentary route (consumption of contaminated dairy products - unpasteurized milk, cheese, butter from infected animals).

68. Most sensitive and informative diagnostic method across all forms of brucellosis: PCR (polymerase chain reaction) - or by some textbooks, blood culture is considered gold standard but PCR has higher sensitivity across all stages.

69. Main reason for treatment failure in chronic brucellosis: Intracellular persistence of Brucella within macrophages/monocytes - Brucella survives inside phagocytes, inaccessible to many antibiotics. This intracellular location prevents antibiotic penetration and clearance.

70. Contact transmission mechanism of infection is most commonly realized in: Veterinary workers, slaughterhouse workers, and animal handlers - direct contact with infected animal tissues, birth products, blood, or urine (contact route involves mucous membranes or broken skin).

71. Antibiotic therapy for brucellosis is considered inappropriate in: Chronic brucellosis with focal lesions in remission (without active replication/bacteremia). In the inactive phase of chronic brucellosis, antibiotics are ineffective because the bacteria are in a dormant intracellular state.

72. Molecular structure determining the S-form of Brucella colonies: O-polysaccharide chain of lipopolysaccharide (LPS) - the O-antigen (O-PS) of the outer membrane LPS determines the smooth (S) colony morphology.

73. Key condition for successful brucellosis prevention: Elimination of brucellosis in animal reservoirs (livestock) through vaccination of animals, culling of infected herds, and veterinary control - without controlling the animal source, human cases cannot be prevented.

74. Most characteristic morphological feature of Kyasanur Forest Disease (KFD): Hemorrhagic necrosis of lymphoid organs (lymph nodes, spleen) and hepatic necrosis. KFD virus (flavivirus) causes systemic vasculitis with hemorrhagic features and lymphoid depletion.

75. Main vector transmitting KFD virus to humans: Hard ticks of the genus Haemaphysalis (primarily Haemaphysalis spinigera) - KFD is a tick-borne hemorrhagic fever in Karnataka, India.

76. Most characteristic laboratory finding in the first phase of KFD: Leukopenia and thrombocytopenia - during the first viremic phase (days 1-9), white blood cell and platelet counts drop significantly.

77. What distinguishes KFD from other flaviviral infections: Biphasic clinical course (two febrile phases separated by an afebrile interval of 1-2 weeks) AND association with monkey deaths (dead langur and bonnet macaque monkeys are sentinel events for KFD outbreaks). Also, significant hemorrhagic manifestations and the specific Haemaphysalis tick vector.

78. Symptom of great diagnostic value in the early phase of KFD: Hemorrhagic manifestations (nasal bleeding, hematemesis, gingival bleeding) combined with fever, severe myalgia, and prostration - especially in the context of forest exposure in Karnataka, India. The finding of dead monkeys in the area is also diagnostically valuable.

79. Feature typical for the second phase of KFD: Neurological manifestations - the second febrile phase (in ~50% of patients) is characterized by meningoencephalitis, mental disturbances, tremors, and abnormal reflexes - distinguishing it from the hemorrhagic first phase.

80. Key pathogenetic factor in development of hemorrhagic syndrome in KFD: Thrombocytopenia + vascular endothelial damage - KFD virus directly damages endothelial cells and causes platelet destruction/consumption, leading to impaired hemostasis and bleeding.

81. Key pathogenic mechanism for Brucella persistence in the host: Intracellular survival within macrophages - Brucella inhibits phagosome-lysosome fusion, suppresses oxidative burst, and manipulates the endoplasmic reticulum to create a "Brucella-containing vacuole" for replication.

82. Organs most frequently affected in chronic brucellosis due to pathogen tropism: Musculoskeletal system (joints, spine - spondylitis, sacroiliitis), genitourinary system (orchitis, epididymitis in men), nervous system (neurobrucellosis), and cardiovascular system (endocarditis - rare but serious).

83. Most characteristic symptom of the undulating course of brucellosis: Recurring waves of fever (undulant fever) - characterized by periods of fever (39-40°C) lasting days to weeks, interspersed with afebrile intervals, giving an "undulant" or "Mediterranean fever" pattern. Associated with profuse sweating and chills.

84. 35-year-old with fever 39.5°C, weakness, headache, myalgia, nausea. Day 5: fine rose-colored rash on trunk (sparing face), leukopenia, thrombocytopenia, elevated CRP. Most likely complication if untreated: Typhoid intestinal perforation/hemorrhage - this presentation is classic for typhoid fever (Salmonella typhi). If untreated, the most serious complication is intestinal perforation (in the 3rd week) or intestinal hemorrhage, both of which are life-threatening.

85. Serological test used as standard for brucellosis diagnosis: Wright's Serum Agglutination Test (SAT) - the standard agglutination test using B. abortus antigen. A titer ≥1:160 (or ≥1:200) is considered significant.

86. Sign distinguishing brucellosis from most other bacterial infections: Leukopenia (with relative lymphocytosis) - unlike most bacterial infections which cause leukocytosis, brucellosis characteristically causes leukopenia or normal WBC count.

87. Complication more common in chronic relapsing brucellosis: Osteoarticular complications (spondylitis, sacroiliitis, arthritis) - these are the hallmark of chronic brucellosis, occurring in up to 30-40% of chronic cases.

88. Clinical feature especially typical for osteoarticular forms of brucellosis: Sacroiliitis - inflammation of the sacroiliac joint is highly characteristic of brucellosis among all arthropathies. Also polyarthritis involving large joints (knees, hips) and spondylitis of the lumbar spine.

89. Most informative laboratory method in early stage of brucellosis: Blood culture (Castaneda method or BACTEC system) - bacteremia is highest during the acute phase, making blood culture the most informative in early brucellosis (though it requires 4-6 weeks and is performed in high-level biosafety facilities).

90. 28-year-old returning from typhus epidemic area, day 3: severe intoxication, tachycardia, maculopapular rash on trunk, leukopenia, moderate anemia. Pathogenetic mechanism of rash in epidemic typhus: Rickettsial invasion and proliferation in vascular endothelial cells - Rickettsia prowazekii infects endothelial cells of small blood vessels, causing perivascular inflammation (typhus nodules/Popov's nodules), vasculitis, thrombosis, and resulting in the characteristic petechial/maculopapular rash.

91. 40-year-old with severe typhus, day 7: high fever, severe intoxication, confusion, tachypnea, tachycardia. Most critical intervention: Immediate administration of Doxycycline (100 mg twice daily) - early antibiotic therapy is the most critical intervention. Doxycycline is the drug of choice for epidemic typhus (Rickettsia prowazekii). Delay in treatment dramatically increases mortality.

92. Urgent notification of an infectious patient is sent to: c. The disinfection department of the State Sanitary and Epidemiological Supervision (Sanitary-Epidemiological Station/Service) - this is the public health authority that must be notified for epidemiological investigation and response.

93. Personal protection against particularly dangerous infections - medical personnel use: Full protective (anti-plague) suit / Type I biological protection suit - consisting of: overalls, hood, respirator (N95/FFP3 or higher), goggles, gloves (double), rubber boots, apron. For plague specifically: anti-plague suit (Type 1).

94. How is active immunity acquired: By introduction of antigens (vaccines) or by having the disease - active immunity involves the body's own immune system producing antibodies and memory cells in response to an antigen (either through natural infection or vaccination).

95. NOT a characteristic epidemiological feature of plague: d. The severity of the disease is not related to the strain of the plague pathogen. This is FALSE (and therefore the answer) - the severity IS related to the strain (e.g., virulence factors vary). All other options are true epidemiological features of plague.

96. Characteristics of a primary bubo in plague: Extremely painful, dense, not fluctuant initially, surrounded by perifocal edema (periadenitis), skin over the bubo is tense, shiny, and reddish-purple, no lymphangitis (lymphangitis is absent - distinguishing it from tularemia). The bubo develops rapidly within 1-2 days.

97. Most important symptom of generalized plague: Infectious toxic shock (septicemia) with DIC - generalized/septicemic plague presents with overwhelming bacteremia, septic shock, DIC with hemorrhagic manifestations, and the characteristic "facies pestica" (mask of plague). The most important/dominant symptom is severe infectious-toxic shock.

98. Cutaneous form of plague is characterized by: A primary affect (carbuncle/pustule/vesicle) at the inoculation site that progresses through: spot → papule → vesicle → pustule → ulcer → eschar. The plague carbuncle is extremely painful (unlike anthrax which is painless) and surrounded by edema. Necrosis is rapid.

99. Feature distinguishing a plague carbuncle from an anthrax carbuncle: Pain - plague carbuncle is extremely painful; anthrax carbuncle is painless (anesthetic). Also: plague carbuncle progresses rapidly with surrounding infiltration and lymphadenitis; anthrax has gelatinous non-pitting edema.

100. In the bubonic form of plague, all of the following changes may be detected EXCEPT: Lymphangitis - bubonic plague characteristically does NOT show lymphangitis (the lymphangitis is absent, unlike in other lymphadenitis). All other changes (painful bubo, periadenitis, fever, leukocytosis, splenomegaly) may be present.

101. Most characteristic signs of primary septicemic form of plague: Overwhelming septicemia without visible bubo, high fever with chills, DIC with hemorrhagic manifestations (petechiae, ecchymoses, bleeding from mucous membranes), rapid progression to septic shock, and "black death" appearance (cyanosis, subcutaneous hemorrhages). Very high mortality.

102. Most typical symptoms of the pneumonic form of plague: Profuse, watery/bloody, frothy sputum, severe chest pain, high fever, rapid progression to respiratory failure. The sputum is initially mucous then becomes bloody/frothy. High contagiousness (airborne transmission). Rapidly fatal without treatment.

103. Materials for bacteriological examination in patients suspected of having plague:

104. For rapid laboratory diagnosis of plague, the following are used: Direct immunofluorescence (DIF), ELISA for F1 antigen, PCR, rapid diagnostic tests (immunochromatographic strips for F1 antigen), and bacterioscopy (Gram stain/Wayson stain showing bipolar "safety-pin" staining of Y. pestis).

105. Routes of human infection with echinococcus: Fecal-oral route - ingestion of eggs of Echinococcus granulosus shed in feces of infected dogs (definitive host). Humans are accidental intermediate hosts. Routes include: contact with infected dogs (petting, licking), contaminated food/water/vegetables, soil contaminated with dog feces.

106. Structure of the echinococcus fin (larval stage/hydatid cyst): The hydatid cyst has: outer pericyst (host-derived fibrous layer), laminated (ectocyst/cuticle layer - acellular), germinal (inner germinal/endocyst) layer which produces brood capsules, protoscolices, and daughter cysts. Inside is hydatid fluid (antigenic, anaphylactic potential).

107. Echinococcosis is best classified as which type of disease: Zoonosis (transmitted from animals to humans) - specifically a helminthiasis (cestodosis) and a bio-helminthiasis.

108. Alveococcosis can be transmitted to humans by: Contact with wild animals (foxes, wolves - definitive hosts) or dogs/cats that have eaten infected rodents. Ingestion of eggs shed in feces of infected foxes/wolves via contaminated berries, vegetables, water, or direct contact. Humans are intermediate hosts for E. multilocularis.

109. Main characteristics of lesions caused by Echinococcus multilocularis in alveolar echinococcosis: Tumor-like, infiltrating growth - unlike the single unilocular cyst of E. granulosus, E. multilocularis forms an alveolar (multilocular) structure of numerous small vesicles embedded in a dense fibrous stroma, which infiltrates and destroys surrounding tissue like a malignant tumor. Most commonly affects the liver and can metastasize. Has very high morbidity and mortality if untreated.

110. Significance of cystic lesions by Echinococcus granulosus in human health: The unilocular hydatid cyst grows slowly over years and can reach large sizes (up to 10-20 cm or more). Complications include: rupture (causing anaphylaxis and dissemination of scolices), compression of adjacent organs (bile ducts causing jaundice, bronchi causing respiratory symptoms), secondary bacterial infection (abscess), and space-occupying lesion effects. Requires surgical or PAIR (Puncture-Aspiration-Injection-Reaspiration) treatment.

111. Significance of different stages of proglottids in Echinococcus granulosus: E. granulosus adult tapeworm has only 3-4 proglottids: immature, mature, and gravid proglottid (containing the uterus filled with eggs). The gravid proglottid is the most significant as it contains 500-800 oncospheres (eggs) that are shed in the feces of the definitive host (dog) and are infectious to intermediate hosts (sheep, humans). The stage of proglottid determines reproductive capacity.

112. Innermost layer of the unilocular hydatid cyst responsible for forming brood capsules: Germinal layer (endocyst/inner germinal epithelium) - this is the inner cellular layer (also called the germinal epithelium) that actively produces brood capsules, protoscolices, and daughter cysts.

113. Brood capsules in context of Echinococcus infection: Small vesicles (0.5-1 cm) that bud from the germinal layer into the hydatid fluid. Each brood capsule contains multiple protoscolices (inverted scolices) - the future heads of adult tapeworms. They represent the asexual reproductive stage within the hydatid cyst.

114. Protoscolices in context of Echinococcus infection: Inverted larval tapeworm heads (scolices) found inside brood capsules within the hydatid cyst. Each protoscolex has 4 suckers and a rostellum with hooks. When a definitive host (dog) ingests the cyst, protoscolices evaginate and develop into adult tapeworms. They are also the source of secondary echinococcosis if a cyst ruptures in humans.

115. Each of the following statements concerning Ascaris lumbricoides is correct EXCEPT: "Larvae do not migrate through the lungs" is INCORRECT (false statement = the answer). Ascaris larvae DO undergo pulmonary migration (Löffler's syndrome). All other statements (largest intestinal nematode, can cause intestinal obstruction, eggs passed in feces, transmitted fecal-orally) are correct.

116. Each of the following statements concerning hookworm infection is correct EXCEPT: "Infection occurs by ingestion of eggs" is INCORRECT. Hookworm (Ancylostoma/Necator) infects humans by skin penetration of filariform larvae (not by ingesting eggs). Eggs in feces → larvae in soil → skin penetration. Iron-deficiency anemia, pulmonary migration are correct features.

117. Pigs or dogs are the source of human infection by each of the following parasites EXCEPT: Taenia saginata (beef tapeworm) - the source is cattle, not pigs or dogs. (Taenia solium = pigs; Echinococcus = dogs; Trichinella = pigs/wild boar are all transmitted from pigs or dogs).

118. The name "helminth" is derived from Greek words helmins/helminthos which means: "Worm" - the Greek word helmins (ἕλμινς) means worm or intestinal worm.

119. 10-year-old girl from Samar with enlarged abdomen, splenomegaly, Kato thick smear shows eggs with lateral knobs (spines). Most likely infection: Schistosoma japonicum - eggs with a small lateral spine/knob are characteristic of S. japonicum (endemic in the Philippines, including Samar). Note: S. mansoni has a prominent lateral spine; S. haematobium has a terminal spine.

120. Drug of choice for schistosomiasis and most trematode infections: Praziquantel - the standard treatment for all Schistosoma species and most trematode (fluke) infections.

121. Drug of choice for taeniasis and most cestode (tapeworm) infections: Praziquantel (or Niclosamide for intestinal tapeworms) - the answer given starts with "A. Metronidazole" but the correct drug of choice for cestodes is Praziquantel (or Niclosamide). Metronidazole is for protozoal infections, not cestodes.

122. Drug of choice for invasive amebiasis, giardiasis, and trichomoniasis: Metronidazole (a nitroimidazole) - drug of choice for all three: Entamoeba histolytica (amebiasis), Giardia lamblia (giardiasis), and Trichomonas vaginalis (trichomoniasis).

123. Recommended diagnostic test for Enterobius vermicularis (pinworm): Scotch tape (cellophane tape) test / adhesive tape test - applied to the perianal area in the early morning before bathing or defecation, to collect eggs deposited by the female worm at night.

124. Best laboratory examination for identifying parasites responsible for chronic diarrhea: Stool microscopy for ova and parasites (O&P examination) - specifically a formal-ether concentration method or trichrome stain of stool for protozoa and helminth eggs. Multiple samples (3 stool samples collected on different days) increase sensitivity.

125. In communities of high socioeconomic status, food-borne amebiasis is transmitted through: Contaminated food prepared by infected food handlers (cooks, restaurant workers who are cyst passers). In high-SES settings, transmission is more commonly via food handlers preparing salads, fruits, or raw vegetables rather than through contaminated water.

126. "Barber's-pole" is one of the diagnostic features of: Haemonchus contortus (a stomach worm of ruminants) - but in the context of human parasitology, this term describes the Trichuris trichiura (whipworm) adult worm appearance OR more commonly refers to Haemonchus. In human parasitology multiple choice contexts, the answer is Trichuris trichiura - the worm has a whip-like shape. Actually the "barber pole" appearance refers to the twisted uterus around the intestine in Haemonchus. In human medicine context, if the question is about intestinal roundworms: the answer expected is likely Trichuris trichiura or Trichostrongylus.

127. Man acquires infection with Trichinella spiralis by: Ingestion of undercooked/raw meat containing encysted larvae (primarily pork, wild boar, bear, or other carnivore/omnivore meat containing Trichinella muscle cysts).

128. Trichinosis in man can be diagnosed by the following EXCEPT: Stool examination - stool microscopy does NOT diagnose trichinosis (larvae are not found in stool). Diagnosis is by: muscle biopsy (compress test), serology (ELISA, immunofluorescence), clinical features + eosinophilia, and skin test (Bachman test).

129. Chiclero's ulcer (usually found in the ear lobe) may be seen in: Cutaneous leishmaniasis (specifically caused by Leishmania mexicana in Mexico/Central America - "chiclero's ulcer" is a form of New World cutaneous leishmaniasis affecting the ear).

130. Anti-cestodal drugs include: A. Praziquantel and Niclosamide - both are effective against cestodes (tapeworms). Praziquantel is preferred for most cestode infections.

131. Liver echinococcosis should be differentiated from all of the following EXCEPT: Acute viral hepatitis - echinococcosis (cystic liver disease) is differentiated from: liver abscess, liver cysts (non-parasitic), hepatocellular carcinoma, liver metastases, alveococcosis. Acute viral hepatitis does NOT present as a cystic lesion and is NOT a differential diagnosis for echinococcosis.

132. Correct life cycle for Taenia solium: Adult tapeworm in human (definitive host) small intestine → gravid proglottids/eggs passed in feces → pigs (intermediate host) ingest eggs → oncospheres hatch → migrate to muscles → form cysticerci (Cysticercus cellulosae) → humans ingest undercooked pork with cysticerci → scolex evaginates and attaches to intestinal wall → adult tapeworm develops. (Cysticercosis occurs when humans accidentally ingest T. solium eggs, becoming the intermediate host.)

133. 48-year-old miner, weakness, headache, dizziness, heaviness in stomach, prior severe leg pruritus and urticaria, anemia, small mobile red worms (~1 cm) in feces. Most likely disease: Hookworm infection (Ancylostomiasis/Necatoriasis) - the history of ground itch (pruritus of legs = larval skin penetration), anemia (iron deficiency from blood sucking), and small red worms (~1 cm, which are hookworms) in stool confirms this diagnosis.

134. Doctor suspects strongyloidiasis - specimens for laboratory testing: Fresh fecal samples (for detection of rhabditiform larvae by direct microscopy or Baermann method/agar plate culture), duodenal aspirate/string test, and in disseminated cases: sputum, BAL, CSF. The most important is fresh stool for larvae (not eggs - Strongyloides is identified by larvae, not eggs, in feces).

135. Helminthiases that are contagious to humans (direct person-to-person transmission): Enterobiasis (pinworm - Enterobius vermicularis) and Hymenolepiasis (dwarf tapeworm - Hymenolepis nana) - these are transmitted directly from person to person or through autoinfection without an intermediate host.

136. Laboratory diagnostic method used for echinococcosis: Serological methods (ELISA, indirect hemagglutination test - IHA/RPHA) detecting anti-echinococcal antibodies. Also: Casoni skin test (intradermal test, historical), immunoelectrophoresis (arc 5 precipitation test). Imaging (ultrasound, CT) is also key but is instrumental, not laboratory. The primary laboratory method is serology (ELISA).

137. Days after eating smoked pork: facial/eyelid swelling, GI upset, high fever, muscle pain, marked eosinophilia. Helminth from pork: Trichinella spiralis - trichinosis/trichinellosis. Classic presentation: facial edema (periorbital), myalgia, fever, and eosinophilia after eating pork products. Smoked pork may not kill Trichinella larvae.

138. 35-year-old lost vision in one eye, history of undercooked shashlik (pork kebab), X-rays + immunological tests → cysticercosis. Causative helminth: Taenia solium (pork tapeworm) - cysticercosis is caused by the larval stage (Cysticercus cellulosae) of Taenia solium, from ingestion of eggs (via contaminated food/fecal-oral) or autoinfection. Ocular cysticercosis can cause visual loss.

139 & 140. Group of hunters with fever, headache, eyelid/facial swelling, muscle pain, history of eating wild boar. Most likely diagnosis: Trichinosis (Trichinellosis) - wild boar is a classic source of Trichinella spiralis. The classic triad of trichinosis: periorbital edema, myalgia, eosinophilia with history of eating wild game.

141. Village residents with eyelid/facial swelling, severe muscle pain, high fever, headache - all ate pork at a wedding 3 weeks earlier. Doctor suspects trichinosis. Method to confirm diagnosis: Muscle biopsy (compress test - squeezing a piece of muscle between glass slides) to find encysted Trichinella larvae microscopically. Also serology (ELISA) for Trichinella antibodies.

142. Invasive stage of Echinococcus granulosus: Oncosphere (hexacanth embryo) - this is the invasive larval stage that hatches from the egg in the duodenum, penetrates the intestinal wall, and migrates via blood/lymph to organs (liver most commonly) where it develops into a hydatid cyst.

143. Fundamental difference between alveococci and echinococci is the shape of the uterus. Shape of alveococcus uterus: Lobed/branched (alveolar) uterus - unlike E. granulosus which has a tubular/saccular uterus, E. multilocularis has a lobed uterus (hence "multilocularis"). The proglottids of E. multilocularis also have a more centrally located genital pore.

144. Diagnosing echinococcosis in humans - crucial methods: Ultrasound/CT scan (imaging), serology (ELISA, IHA), and Casoni intradermal test (historical). When surgical specimens are available: histopathology showing the laminated membrane.

145. Autopsy: liver with 5 cm round, smooth-surfaced cyst, numerous small vesicles inside with clear colorless fluid, sclerotic surrounding tissue. Most likely diagnosis: Echinococcosis (Cystic echinococcosis / hydatid disease) caused by Echinococcus granulosus - the unilocular hydatid cyst with daughter cysts (small internal vesicles) is pathognomonic.

146. Family cluster with eyelid/facial swelling, fever, eosinophilia, headache, muscle pain - 10 days after eating sausage and lard from rural relatives. Most likely parasitic disease: Trichinosis (Trichinellosis) - sausage and lard from rural areas (home-slaughtered pigs without veterinary inspection) is a classic source of Trichinella. The 10-day incubation and periorbital edema + myalgia + eosinophilia confirm this.

147. Helminthiasis where prohibition of consuming infected meat even after cooking is emphasized: Trichinosis (Trichinellosis) - Trichinella larvae can survive smoking, salting, and mild cooking. Only thorough cooking (internal temperature >71°C) or deep freezing kills the larvae. This is why prohibition of consuming infected meat "even after cooking" (without proper methods) is emphasized.

148. Feature distinguishing bubonic plague from bubonic tularemia: Extreme pain and periadenitis (perifocal edema around the bubo) in plague vs. tularemia bubo which is less painful with no periadenitis. Also: in plague, bubo develops rapidly (1-2 days) vs. tularemia (1-2 weeks). Plague has more severe systemic toxicity. In tularemia, there is often a primary ulcer (ulceroglandular form); in plague, the primary affect may be absent.

149. Bubonic form of plague differs from suppurative lymphadenitis: Absence of lymphangitis in plague (no red streaks), extreme tenderness + periadenitis in plague (surrounding edema merging tissues), and skin over the bubo is not bright red/localized initially in plague. In suppurative lymphadenitis: lymphangitis is present, less systemic toxicity, no periadenitis, fluctuant sooner.

150. Causative agent of plague: Yersinia pestis (formerly Pasteurella pestis) - a Gram-negative coccobacillus belonging to family Enterobacteriaceae.

151. The plague pathogen belongs to the family: Yersiniaceae (or Enterobacteriaceae by older classification) - Yersinia pestis is in the family Yersiniaceae, order Enterobacterales.

152. Structure of the plague pathogen (Yersinia pestis): Gram-negative, ovoid/coccobacillus with bipolar staining ("safety-pin" appearance) with Wayson/methylene blue stain. Has capsule (F1 antigen), outer membrane proteins (Yops - Yersinia outer proteins), LPS (endotoxin), plasminogen activator (Pla). Non-motile at 37°C (motile at 28°C). Facultative anaerobe.

153. Generalized form of plague is: Secondary septicemic plague (secondary to bubonic or pneumonic) OR Primary septicemic plague - the generalized form is characterized by overwhelming bacteremia with dissemination to all organs, DIC, hemorrhagic manifestations, and septic shock.

154. Feature distinguishing purulent lymphadenitis from bubonic plague: Presence of lymphangitis in purulent lymphadenitis (absent in plague); less severe systemic toxicity in purulent lymphadenitis; localized fluctuance and skin redness in purulent lymphadenitis vs. periadenitis in plague; identifiable primary infection source (wound, skin infection) in purulent lymphadenitis.

155. Changes in general blood count in plague patients: Leukocytosis with neutrophilia and shift to the left (unlike typhus/brucellosis which cause leukopenia). High WBC (15,000-25,000 or more), neutrophilia, elevated ESR, toxic granulation of neutrophils, thrombocytopenia in severe cases.

156. Incubation period for the pneumonic form of plague: 1-3 days (range: hours to 3 days) - pneumonic plague has the shortest incubation period of all plague forms. Without treatment, death occurs within 24-72 hours of symptom onset.

157. Intestinal manifestations of plague: Nausea, vomiting, abdominal pain, diarrhea (sometimes bloody) - these occur due to gut involvement in septicemic plague or primary intestinal plague (rare). Also called "abdominal plague" in some sources.

158. Typical appearance of skin over plague buboes: Initially normal/reddish, then as disease progresses becomes tense, shiny, and erythematous - the overlying skin is stretched due to periadenitis and edema. Later may become bluish-purple/cyanotic. The bubo is NOT fluctuant initially.

159. Cutaneous anthrax is different from cutaneous plague by: Anthrax: painless eschar; Plague: extremely painful lesion. Also, anthrax has gelatinous non-pitting edema; plague carbuncle/skin lesion progresses rapidly with purulent/necrotic center and severe regional lymphadenopathy (bubo). Anthrax has characteristic "malignant pustule" with central necrosis and peripheral vesicles.

160. Cutaneous form of plague differs from bubonic form of plague: In cutaneous plague, there is a primary skin lesion (carbuncle/eschar) at the inoculation site which is the predominant feature; in bubonic plague, the primary affect may be absent or minimal, and the bubo is the dominant finding.

161. Cutaneous plague is different from cutaneous anthrax: Pain - plague skin lesion is very painful; anthrax is painless. Plague carbuncle progresses to rapid suppuration and necrosis; anthrax forms a dry black eschar with gelatinous edema. Regional lymph nodes: plague forms a classic bubo; anthrax has milder lymphadenopathy.

162. Mortality rate of untreated primary septicemic plague: ~100% (essentially 100% fatality) - primary septicemic plague is nearly universally fatal without antibiotic treatment, and even with treatment mortality remains 30-50%.

163. Facial appearance most commonly observed in generalized forms of plague: "Facies pestica" (mask of plague) - characterized by: puffiness, dark circles under eyes, facial suffusion, conjunctival injection, anxious/terrified expression. The face appears "like a mask" with dull, glazed eyes.

164. Localized form of plague is: Bubonic plague (and cutaneous plague) - the localized form is confined to the lymph nodes (bubo) and surrounding tissue without systemic dissemination.

165. Material for bacteriological examination in bubonic form of plague: Bubo aspirate (puncture fluid from the bubo) - obtained by needle aspiration of the bubo. This is the primary specimen for culture, microscopy, and PCR.

166. Material for bacteriological examination in cutaneous plague: Vesicle/pustule content, eschar material, carbuncle exudate - from the primary skin lesion.

167. Material for bacteriological examination in pulmonary (pneumonic) form of plague: Sputum - expectorated sputum (which is highly infectious in pneumonic plague - airborne precautions are essential when handling).

168. Most dangerous form of plague as a source of infection for others: Pneumonic plague - transmitted by airborne droplets, extremely contagious, with a very short incubation period. A single cough can transmit to multiple people.

169. Least dangerous form of plague as a source of infection for others: Bubonic plague (without secondary pneumonia) - not transmitted person-to-person directly; requires flea vector. Patients are infectious only if they develop pneumonic complications or if a flea bites them and then another person.

170. Typical onset of plague: Sudden/acute onset - plague typically begins abruptly with sudden high fever (39-40°C), severe chills, intense headache, myalgia, and rapid prostration. The onset is characteristically abrupt within hours.

171. Non-specific complications of plague: Pneumonia (secondary bacterial pneumonia), meningitis, pericarditis, endocarditis, DIC, septic shock, peripheral gangrene ("black death" - acral necrosis from DIC/vasculitis).

172. Main vectors of Yersinia pestis in vector-borne transmission: Fleas - primarily Xenopsylla cheopis (rat flea) and other rodent fleas (Pulex irritans, Ceratophyllus species). The flea becomes infected by feeding on bacteremic rodents.

173. Main pathogenicity factor of Yersinia pestis contributing to infectious-toxic shock: Endotoxin (LPS/lipopolysaccharide) - the lipid A component of Y. pestis LPS triggers massive cytokine release (TNF-α, IL-1, IL-6), leading to septic shock, DIC, and MODS. Also: F1 capsular antigen (anti-phagocytic) and Pla protease contribute.

174. Main sources of infection in plague in anthropurgical (urban/secondary) foci: Rats (Rattus rattus, Rattus norvegicus) - urban rats are the main reservoir in anthropurgical plague foci, with rat fleas transmitting to humans.

175. Main sources of infection in plague in natural foci: Wild rodents - ground squirrels (Citellus/Spermophilus), marmots, gerbils, prairie dogs, voles - these are the primary natural reservoir hosts in sylvatic plague foci.

176. Main pathogenic mechanism in human toxocariasis: Larva migrans syndrome - Toxocara canis/cati larvae hatch in the human intestine, penetrate the gut wall, and migrate through tissues (liver, lungs, eyes, brain) causing visceral larva migrans (VLM) or ocular larva migrans (OLM). Host granulomatous response to the migrating larvae causes tissue damage and eosinophilia.

177. How humans most commonly acquire toxocariasis: Ingestion of embryonated Toxocara eggs from soil contaminated with dog or cat feces. Children playing in sandboxes or soil, and contact with dogs/cats are risk factors. Geophagia (pica) is a major risk factor in children.

178. Bacteriological method of diagnosis (culture isolation) for brucellosis is characterized by: High specificity but low sensitivity and long incubation time (4-6 weeks), requiring BSL-3 facilities, Castaneda biphasic medium or BACTEC system, high biosafety risk. Blood culture is most positive in the acute phase.

179. Characteristics of Brucella spp: Intracellular facultative - Brucella is a facultative intracellular pathogen (it can survive and replicate inside macrophages but can also be cultured extracellularly). It is NOT obligate intracellular and NOT a soil organism in the traditional sense.

180. Brucellosis in humans is characterized by: Undulant fever, profuse sweating (especially nocturnal), weakness, arthralgia/arthritis, hepatosplenomegaly, lymphadenopathy, leukopenia with relative lymphocytosis, and potential focal complications (orchitis, spondylitis, neurobrucellosis).

181. If a patient presents with symptoms suggestive of brucellosis, which investigation should be performed in a healthcare setting: Wright's agglutination test (SAT) as a rapid screening serological test, followed by blood culture for confirmation. ELISA and rose bengal test are also used.

182. MLVA (Multiple Locus Variable-number tandem repeat Analysis) method for typing Brucella isolates provides the opportunity to: Differentiate Brucella strains at subspecies/biotype level, track outbreak sources, establish molecular epidemiological links between human cases and animal reservoirs, and identify the geographic origin of strains.

183. Type of inflammation developing in tissues affected by brucellosis: Granulomatous inflammation - Brucella induces the formation of granulomas in the reticuloendothelial system (liver, spleen, lymph nodes, bone marrow). These granulomas lack caseation (unlike TB) and consist of epithelioid cells, lymphocytes, and giant cells.

184. Brucella species most associated with spring-summer seasonality of human brucellosis: Brucella melitensis (goat/sheep brucellosis) - lambing and kidding season is in spring, when large amounts of infectious birth products (placenta, amniotic fluid) are shed. Milk production also peaks in spring-summer, increasing alimentary exposure.

185. During which stages of illness can an infected person act as a source of brucellosis infection: Brucellosis is generally NOT transmitted person-to-person (except in rare cases: sexual transmission, blood transfusion, bone marrow transplant, breastfeeding). An infected person is NOT considered an epidemiologically significant source.

186. Recommended duration of induction therapy for non-tuberculous mycobacteriosis (NTM) in patients with HIV infection: At least 12 months (some guidelines recommend until 6 months after immunological reconstitution with ART, with CD4 count >100 cells/μL for at least 6 months).

187 (first one). Monitoring nephrotoxicity of drugs in HIV patients - how often to measure creatinine and GFR: Every 3-6 months during stable ART; more frequently (monthly) when nephrotoxic drugs (tenofovir) are started or when renal function is declining.

187 (second - Q188). Occupational group subject to routine preventive serological screening for brucellosis in endemic regions: Livestock workers, veterinarians, slaughterhouse workers, dairy farm workers, laboratory personnel handling Brucella specimens - all persons in occupational contact with potentially infected animals or animal products.

188 (Q189 numbering). Dissemination of brucellae into internal organs is mainly ensured by: Intracellular transport within macrophages/monocytes (Trojan horse mechanism) - Brucella survives inside phagocytes and uses them as vehicles to disseminate to liver, spleen, bone marrow, and lymph nodes through the lympho-hematogenous route.

189. Brucella species characterized by S-shaped (smooth) colonies: Brucella melitensis and Brucella abortus in their smooth (S) form. B. canis and B. ovis naturally occur in rough (R) form. The S-form is characterized by intact O-polysaccharide LPS chains.

190. Main antibiotic for treatment of brucellosis: Doxycycline - the cornerstone of brucellosis treatment. Standard regimen: Doxycycline 100 mg twice daily for 6 weeks + Rifampicin 600-900 mg/day for 6 weeks (or Doxycycline + Streptomycin for severe disease).

191. Vaccines used for brucellosis prevention: Live attenuated vaccine (Brucella abortus strain 19 or strain RB51) - used for animal vaccination. For humans, live attenuated vaccine from B. abortus (strain 104-M) has been used in some countries (Russia/former USSR). No licensed human brucellosis vaccine is widely available internationally.

192. Nature of immunity in humans after acquired brucellosis: Non-sterile, short-lived immunity - immunity is primarily cellular (T-cell mediated), not strongly protective, and reinfection is possible. Immunity lasts approximately 1-2 years and is not fully protective against reinfection.

193. Group of infectious diseases brucellosis belongs to: Zoonoses (animal-to-human transmissible infections) - specifically a bacterial zoonosis in the group of sapro-zoonoses (vector: environment/food) and contact zoonoses.

194. Healthcare measures for prevention of brucellosis: Pasteurization of milk and dairy products, health education, occupational protective measures (gloves, masks for workers), vaccination of high-risk occupational groups, medical surveillance of at-risk workers, proper handling of animal birth products.

195. Antiepizootic measures include: Vaccination of livestock (B. abortus S-19, RB51 for cattle; Rev-1 for small ruminants), serological testing and culling of infected animals, quarantine of infected herds, disinfection of premises, proper disposal of abortions/placentas, movement controls.

196. Molecular structure determined by the S-shape of Brucella colonies: O-polysaccharide (O-antigen) of lipopolysaccharide (LPS) - identical to Q72.

197. Key to successful brucellosis prevention: Elimination of brucellosis in animal populations (herds) through systematic vaccination and testing/slaughter programs - same as Q73.

198. Contact transmission is most common mechanism when: Direct contact with infected animal birth products (placenta, fetal fluids, amniotic fluid during calving/lambing/kidding) occurs, or contact with infected animal carcasses in slaughterhouses - through mucous membranes or abraded skin.

199. Prescribing antibiotics is considered incorrect in brucellosis treatment: In the inactive phase of chronic brucellosis (without active inflammation/bacteremia) - antibiotic therapy is ineffective because bacteria are in dormant intracellular form with no active replication. Treatment in inactive chronic phase yields no benefit.

200. Most severe course of disease in humans is caused by the species: Brucella melitensis - the most virulent species causing the most severe and acute disease in humans (goat/sheep brucellosis). B. abortus (cattle) causes milder disease; B. suis (pigs) intermediate severity; B. canis causes mild sporadic disease.

201. Brucellosis infection in humans most commonly occurs in absence of direct contact with the source via: Alimentary route (consumption of raw milk, unpasteurized dairy products, undercooked meat from infected animals) - same as Q67.

202. Most sensitive and informative diagnostic method for all forms of brucellosis: PCR (Polymerase Chain Reaction) - same as Q68. PCR detects Brucella DNA even in chronic forms when culture and serology may be negative.

203. Ineffective treatment of chronic brucellosis is associated with: Intracellular persistence of Brucella within macrophages - bacteria are protected from antibiotics by the intracellular environment. The phagosomal location prevents adequate drug concentration reaching the organisms.

204. Main difference between foci of "goat-sheep" and "cow" brucellosis: B. melitensis (goat-sheep) foci are much more epidemically active with higher risk of human infection and more severe disease; B. abortus (cattle) foci cause less intense epizootics with sporadic human cases and milder disease.

205. Main epidemic and epizootic unfavourability for brucellosis is determined by: Brucella melitensis - the most dangerous species with highest virulence, widest host range, and greatest epidemic potential.

206. Main source of infection in brucellosis: Small ruminants (goats and sheep) infected with B. melitensis are the primary source globally. Cattle (B. abortus), pigs (B. suis), and dogs (B. canis) are other sources.

207. Main mechanisms of animal-to-human transmission of the brucellosis pathogen: Alimentary (ingestion of contaminated milk/dairy products), contact (direct contact with infected animals/birth products through skin/mucous membranes), and aerosol (inhalation of contaminated dust in animal pens/slaughterhouses).

208. Difference between foci of infection in epizootology and epidemiology: In epizootology: focus refers to the territory where an infectious disease circulates among animals (reservoir host + vector + environment). In epidemiology: focus refers to the place of infection including the source, susceptible population, and transmission routes. The key difference is that epizootology focuses on animal disease dynamics while epidemiology focuses on human disease patterns and the interaction between the two.

209. "Bovine" brucellosis outbreak is characterized by: Lower epidemic activity compared to goat-sheep brucellosis, predominantly affecting workers in direct contact with cattle (veterinarians, farmers, slaughterhouse workers), with mainly professional/occupational transmission, and milder clinical disease in humans.

210. Periodic medical examinations of occupational contingents at risk of brucellosis are conducted by: Occupational health physicians / Industrial hygiene specialists - in coordination with sanitary-epidemiological services, periodic medical examinations include clinical examination + serology (Wright's test, Rose Bengal test) at least annually.

211. Indication for vaccination against brucellosis: Working in endemic areas with occupational contact with potentially infected animals or animal products - specifically: livestock workers, veterinarians, slaughterhouse workers, laboratory workers in Brucella-endemic regions.

212. Form of disease where agglutination reaction is most sensitive and informative: Acute brucellosis - same as Q65.

213. For induction and maintenance therapy of NTM in HIV patients, anti-TB drugs are used together with: Macrolides (Clarithromycin or Azithromycin) - the standard regimen for MAC (Mycobacterium avium complex, the most common NTM in HIV) is: Clarithromycin (or Azithromycin) + Ethambutol ± Rifabutin.

214. AIDS is diagnosed if a person with HIV infection has: CD4+ T-lymphocyte count <200 cells/μL OR presence of an AIDS-defining condition (Category C illness) - such as Pneumocystis pneumonia, CMV retinitis, Kaposi's sarcoma, cerebral toxoplasmosis, cryptococcal meningitis, etc. (CDC 1993 definition).

215. Increased virulence and immunogenicity associated with which colony cell shape of brucellae: Smooth (S) form - same as Q64.

216. Brucella species that cause sporadic disease in humans: Brucella canis (from dogs) and Brucella suis (from pigs) - same as Q63.

217. Vaccination tactics for people against brucellosis depends on: Epidemiological situation (whether B. melitensis or B. abortus is circulating, epizootic activity among livestock), occupational risk, and serological status of the individual (previous exposure/vaccination history).

218. Responsible for confirming diagnosis and prescribing treatment for brucellosis: Infectious disease specialist (infectiologist) - confirmation of brucellosis diagnosis and treatment should be done by or in consultation with an infectious disease specialist.

219. To form immunity against TBE by beginning of epidemic season, first dose of vaccine is administered: In autumn-winter (November-December) - same as Q58.

220. Opisthotonus is associated with tonic muscle tension of: The back extensor muscles (spinal extensors) - opisthotonus is an extreme arching of the back with the head and heels bending backward, caused by tonic spasm of the back extensors (erector spinae). This is seen in severe tetanus and meningitis.

221. Main symptom of the initial period of tetanus: Trismus (lockjaw) - the earliest and most characteristic symptom of tetanus, caused by spasm of the masseter muscles making it impossible to open the mouth. Often accompanied by risus sardonicus (sardonic smile) due to facial muscle spasm.

222. Main pathogenicity factor of Clostridium tetani: Tetanospasmin (tetanus neurotoxin) - a zinc-dependent metalloprotease that cleaves synaptobrevin (VAMP) in inhibitory interneurons (Renshaw cells in the spinal cord and GABA-ergic interneurons in the brainstem), blocking release of GABA and glycine, resulting in unopposed excitation and spastic paralysis.

223. Pleurostotonus is associated with tonic muscle contraction of which muscle group: Lateral trunk muscles (unilateral) - pleurostotonus refers to lateral body arching (one side), caused by unilateral contraction of the lateral trunk/paraspinal muscles, in contrast to opisthotonus (bilateral back extensors) or emprosthotonos (anterior muscles).

224. Effect of increased sympathetic nervous system activity in tetanus: Autonomic dysfunction syndrome - includes: tachycardia, hypertension (alternating with hypotension), profuse sweating, hyperthermia, cardiac arrhythmias. This autonomic instability is a major cause of death in modern tetanus (now that ventilator support has reduced deaths from respiratory failure).

225. Complete course of routine immunization of newborns against tetanus - regimen: Three doses of DTP/DT vaccine at 2, 4, and 6 months of age (primary series), plus boosters at 18 months and at school age. The primary series consists of 3 doses of tetanus toxoid as part of DTP vaccination.

226. In bacteriological diagnosis of tetanus, most rational test: Anaerobic culture of wound material (wound exudate, necrotic tissue) on blood agar or thioglycollate broth under anaerobic conditions to isolate C. tetani. However, culture is rarely positive and the diagnosis is primarily clinical. The most rational test is wound culture under anaerobic conditions.

227. How long must spores of Clostridium tetani be boiled to be killed: At least 1 hour (60 minutes) of boiling at 100°C. C. tetani spores are highly heat-resistant; autoclaving at 121°C for 15-20 minutes is required for reliable sterilization.

228. Prophylactic dose of anti-tetanus serum (ATS): 3,000 IU (international units) - the standard prophylactic dose of heterologous (equine) anti-tetanus serum (ATS) given after injury to non-immunized individuals (must be preceded by sensitivity testing).

229. Pathway of transmission of Clostridium tetani: Wound/traumatic inoculation - C. tetani spores enter through wounds (penetrating trauma, deep lacerations, burns, animal bites, surgical wounds, umbilical cord in neonatal tetanus). The organism does NOT spread person-to-person.

230. Average therapeutic dose of anti-tetanus human immunoglobulin (HTIG): 500-3,000 IU for prophylaxis; 3,000-6,000 IU for treatment of active tetanus. The standard therapeutic dose is 3,000-6,000 IU IM (human TIG is preferred over equine ATS as it has longer half-life and no anaphylaxis risk).

231. Source of infection in HIV infection: HIV-infected person (regardless of clinical stage, including asymptomatic seropositive individuals) - the only source is an infected human. HIV is NOT zoonotic.

232. Brunner's tetanus (cephalic tetanus) is characterized by predominantly muscle damage of: Facial muscles and cranial nerve-innervated muscles - cephalic (head) tetanus typically follows head wounds and presents with trismus + involvement of cranial nerves (especially CN VII - facial nerve palsy), giving a mixed picture of tetanus + facial nerve palsy.

233. Epidemiological classification of tetanus: Tetanus is classified as: 1) Neonatal tetanus (umbilical infection), 2) Post-traumatic tetanus (wound tetanus), 3) Post-surgical tetanus, 4) Idiopathic tetanus (no identifiable wound), 5) Puerperal tetanus (post-partum). By epidemiology: sporadic, non-contagious, wound-associated disease.

234. Criterion for virological failure of ART: repeated detection of viral load >50 copies/mL (or above detection threshold) after how many months of ART: After 6 months of ART - virological failure is defined as confirmed viral load >50 copies/mL (or detectable above assay threshold) on two measurements at least 2-4 weeks apart, after 6 months of continuous ART.

235. Emergency initiation of ART is recommended if CD4+ count is less than: 200 cells/μL (some guidelines say <350 cells/μL for standard initiation; <200 cells/μL triggers urgent/emergency initiation due to high risk of OIs). WHO 2021 guidelines recommend ART for all regardless of CD4 count, with urgent initiation when CD4 <200.

236. Clostridium tetanospasmin (tetanus neurotoxin) causes: Spastic paralysis by blocking inhibitory neurotransmitter release (GABA and glycine) in the spinal cord and brainstem - results in unopposed motor neuron activity, causing rigid muscle spasms and convulsions.

237. Urgent procedure for prescribing ART involves starting treatment after HIV detection at the latest within: 7 days of HIV diagnosis (WHO recommends ART initiation as soon as possible, ideally on the day of diagnosis; urgent initiation protocols aim for within 7 days).

238. Trismus manifests clinically as: Inability to open the mouth fully (lockjaw) due to bilateral masseter muscle spasm. Measured as restricted jaw opening (interincisal distance <35 mm). It is the classic first symptom of tetanus.

239. Tick-borne encephalitis is: A natural-focal, transmissible (vector-borne), acute viral infection caused by TBE virus (Flaviviridae family), transmitted by Ixodes ticks, characterized by biphasic course and involvement of the CNS (meningitis, encephalitis, myelitis).

240. Primary reproduction of TBE virus occurs in: Skin dendritic cells (Langerhans cells) and subcutaneous macrophages at the tick bite site - this is the initial site of replication before the virus drains to regional lymph nodes and causes the first viremia.

241. Only clinical manifestation of HIV infection in the subclinical (asymptomatic) stage: Persistent generalized lymphadenopathy (PGL) - enlarged lymph nodes (>1 cm) in ≥2 extra-inguinal sites for ≥3 months without other explanation is the only clinical sign during the subclinical/latent phase.

242. For NTM induction and maintenance therapy in HIV patients, anti-TB drugs + (same as Q213): Clarithromycin or Azithromycin (macrolides) + Ethambutol ± Rifabutin for MAC.

243. ART for HIV is considered effective if viral load after 6 months of therapy is: Below the detection threshold (<50 copies/mL, or undetectable) - virological success is defined as viral load suppression to undetectable levels (<50 copies/mL) after 6 months of ART.

244. Initiation of ART for HIV should be recommended: For all HIV-infected individuals regardless of CD4 count or clinical stage - WHO 2016 "treat all" guidelines recommend immediate ART for everyone with HIV. Urgent initiation for CD4 <200 or AIDS-defining illness.

245. All HIV-infected people with confirmed CMV infection/manifest CMV disease should be treated with Ganciclovir or Valganciclovir for at least: 21 days (3 weeks) for induction therapy - standard treatment for CMV retinitis or other end-organ disease is Ganciclovir/Valganciclovir induction for 14-21 days, followed by maintenance therapy.

246. 30-year-old woman with sudden onset of muscle spasm, neck stiffness, headache, restlessness. Distinguishing tetanus from meningoencephalitis - which finding indicates tetanus: Normal CSF (normal cerebrospinal fluid analysis) - in tetanus, CSF is normal (no pleocytosis, normal protein and glucose). In meningoencephalitis, CSF shows inflammatory changes (pleocytosis, elevated protein, etc.). Also: trismus (lockjaw) is present in tetanus but not meningoencephalitis; consciousness is preserved in tetanus (vs. altered in meningoencephalitis).

247. Characteristic of Listeria monocytogenes that increases infection risk for immunocompromised patients: Intracellular pathogen - L. monocytogenes is a facultative intracellular bacterium that survives within macrophages. It uses ActA protein for actin-based motility to spread cell-to-cell, evading humoral immunity. Immunocompromised patients (impaired cell-mediated immunity) cannot clear it effectively.

248. Phase of infectious process in brucellosis corresponding to the incubation period: Phase of lymphogenous dissemination - during the incubation period (1-3 weeks), brucellae are transported from the entry site (gut/skin/respiratory tract) via lymphatics to regional lymph nodes, where primary multiplication occurs before systemic spread.

249. Injuries especially dangerous for development of tetanus when C. tetani is inoculated: Deep, penetrating, anaerobic wounds - specifically: puncture wounds, crush injuries, wounds with devitalized tissue, burns, compound fractures, wounds contaminated with soil/manure, bite wounds. The anaerobic environment (devitalized tissue, poor blood supply) promotes spore germination and toxin production.

250. Clinical feature distinguishing rabies from tetanus: Hydrophobia and aerophobia are characteristic of rabies; consciousness is altered/lost in rabies (encephalitis). In tetanus: consciousness is preserved, no hydrophobia, trismus is dominant. Also: autonomic dysfunction with salivation/hypersalivation and bizarre behavior in rabies vs. rigid spasms without mental changes in tetanus.

251. Main clinical symptoms of acute brucellosis - correct combination: All four: 1) fever, lymphadenopathy; 2) chills, sweating; 3) enlarged liver and spleen; 4) focal lesions - the correct combination includes all of these features. The answer is the combination that includes ALL: fever + lymphadenopathy + chills/sweating + hepatosplenomegaly + focal organ lesions.

252. For accelerated laboratory diagnosis of plague: Direct immunofluorescence (DIF), ELISA for F1 antigen, PCR, immunochromatographic (dipstick) rapid tests for F1 antigen - same as Q104.

253. Serious consequences associated with brucellosis (sequelae): Chronic spondylitis/sacroiliitis (back deformity, disability), orchitis/epididymitis (infertility in men), neurobrucellosis (meningitis, encephalitis, peripheral neuropathy), endocarditis (rare but most common cause of brucellosis death), ocular complications (uveitis).

254. Acute renal failure in leptospirosis develops as a result of which mechanism: Direct toxic injury to renal tubular epithelium by leptospiral toxins and outer membrane components, leading to acute tubular necrosis (ATN). Immune complex deposition in glomeruli (glomerulonephritis) also contributes. The result is non-oliguric renal failure (tubular rather than glomerular primarily).

255. Antibiotic prophylaxis for asymptomatic individuals exposed to pneumonic plague. Drug usually used: Doxycycline 100 mg twice daily for 7 days - or Ciprofloxacin 500 mg twice daily for 7 days (for pregnant women and children). These are the WHO/CDC recommended post-exposure prophylaxis regimens.

256. Pulmonary tuberculosis differs from ornithosis (psittacosis) by the presence of: Cavitation, fibrosis, upper lobe predilection, mycobacterial etiology, positive Mantoux/IGRA test, sputum AFB smear positivity, chronic course. TB has cavitation; ornithosis typically does not. TB is chronic; ornithosis is acute.

257. Ornithosis differs from pulmonary tuberculosis by the presence of: Epidemiological link to birds (parrots, pigeons, ducks), acute onset with high fever, relative bradycardia (Faget's sign), splenomegaly, absence of upper lobe cavitation, positive serology for Chlamydia psittaci, and rapid response to tetracyclines/macrolides.

258. Ornithosis and pulmonary tuberculosis have in common: Interstitial/atypical pneumonia pattern on chest X-ray, cough (may be non-productive initially), fever, general malaise and weakness, and both can present as lower respiratory tract infection. Both may have prolonged course.

259. Emergency immunoprophylaxis for tetanus should be given as early as possible and until: 7-20 days after injury - emergency prophylaxis is most effective when given promptly; the window is the incubation period of tetanus (average 7-10 days, up to 3 weeks). It should be given until the wound has healed and the risk period has passed.

260. Average therapeutic dose of tetanus serum (ATS - heterologous, equine): 100,000 - 200,000 IU for therapeutic use in active tetanus (compare with 3,000 IU prophylactic dose). The large therapeutic dose is given in multiple injections after desensitization testing.

261. Blockade of brainstem reticular neurons in tetanus promotes: Loss of inhibitory control over autonomic centers, contributing to autonomic dysfunction (sympathetic hyperactivity - tachycardia, hypertension, hyperthermia, sweating) and respiratory center dysfunction (respiratory arrest). Blockade of inhibitory reticular neurons also contributes to tonic-clonic spasms.

262. Emergency specific rabies prophylaxis may be discontinued after the 3rd vaccination if: The animal is observed for 10 days and remains healthy OR the animal is tested and confirmed negative for rabies by laboratory examination. If the biting animal is confirmed rabies-free, further vaccination is unnecessary.

263. Atypical (paralytic) form of rabies develops more often after bites from: Bats (vampire bats) - paralytic/dumb rabies (Dumb form) is more commonly seen after bat bites. It presents with ascending paralysis (Guillain-Barré-like) rather than the classic furious form with hydrophobia.

264. Ulcerative bubonic form of tularemia differs from (purely) bubonic form of tularemia: Presence of a primary ulcer (primary affect) at the site of pathogen entry in the ulceroglandular form vs. absence of visible primary lesion in the purely bubonic (glandular) form. In ulceroglandular tularemia: a papule → ulcer at the bite site + regional bubo.

265. Clinical feature distinguishing cutaneous anthrax from bubonic tularemia: Painlessness of the anthrax lesion and characteristic black eschar in anthrax vs. painful ulcer with clean base and regional painful bubo in tularemia. Anthrax has gelatinous non-pitting edema; tularemia has softer, more typical inflammatory edema.

266. Cutaneous anthrax is different from cutaneous leishmaniasis: Anthrax: rapid progression (days), painless black eschar, gelatinous edema, systemic toxicity, can rapidly become septicemic. Cutaneous leishmaniasis: chronic indolent ulcer (weeks-months), painless (usually), no gelatinous edema, "volcano crater" appearance with raised borders, no black eschar, minimal systemic symptoms, geographical exposure to sandflies.

267. Clinical feature distinguishing cutaneous anthrax from cutaneous bubonic plague: Painlessness in anthrax vs. pain in plague. Anthrax: non-pitting gelatinous edema, black eschar, painless. Plague carbuncle: extremely painful, rapidly necrotic, with formation of a bubo. The presence of a classical painful bubo is more prominent in plague.

268 & 269. Epidemiological surveillance for brucellosis is based on: Animal surveillance data (seroprevalence in livestock), human case reporting and epidemiological investigation, laboratory confirmation of cases, monitoring of high-risk occupational groups, milk and dairy product testing, and veterinary disease reporting from farms and slaughterhouses.

270. Brucella species that cause sporadic human disease: Brucella canis and Brucella suis - same as Q63 and Q216.

271. Key to successful brucellosis prevention: Elimination of brucellosis in animal reservoirs - same as Q73, Q197.

272. Nature of immunity after acquired brucellosis: Non-sterile, short-duration, primarily cellular immunity - same as Q192.

273. Clinical course of brucellosis in humans: Varies widely: can be acute (up to 3 months), subacute (3-12 months), or chronic (>12 months with recurrent or persistent symptoms). May have an undulant fever pattern. Can have focal complications. Without treatment, tends to become chronic with relapses.

274. Clinical feature especially typical for the edematous form of cutaneous anthrax: Massive gelatinous (non-pitting) edema spreading beyond the primary lesion site, often involving the entire face, neck, or limb, without an obvious central eschar (the eschar may be obscured by the edema). Systemic toxicity is severe. This form has the highest mortality among cutaneous forms.

275. Non-invasive route of entry of Yersiniae into the body: Alimentary (oral) route without mucosal invasion - ingestion of contaminated food/water where Yersinia passively enters via M cells in Peyer's patches without direct tissue invasion through intact mucosa (though it does ultimately invade lymphoid tissue).

276. Most common outcome of rash in Yersiniosis: Desquamation (peeling) - the scarlatiniform or maculopapular rash of yersiniosis typically resolves with desquamation (skin peeling), similar to scarlet fever.

277. Leptospirosis differs from Yersiniosis by the presence of which symptoms: Jaundice (icterus) and renal failure in leptospirosis (Weil's disease); acute onset, severe myalgia (calf pain), hemoptysis - these are more characteristic of leptospirosis. Yersiniosis has prominent abdominal pain/pseudoappendicitis, mesenteric lymphadenitis, and arthritis.

278. Form of yersiniosis where mesenteric lymphadenitis is more common: Abdominal (pseudoappendiceal) form of Y. enterocolitica infection - characterized by right iliac fossa pain mimicking appendicitis, with mesenteric lymphadenitis as the predominant finding at laparotomy.

279. Conditions classified as secondary focal forms of yersiniosis: Arthritis (reactive arthritis/Reiter's syndrome), erythema nodosum, uveitis, myocarditis, hepatitis, glomerulonephritis - these are the secondary focal (post-infectious reactive) manifestations of yersiniosis, typically occurring 2-4 weeks after the primary infection.

280. Invasive route of entry of Yersiniae into the body: Penetration through intestinal mucosa (M cells in Peyer's patches) → invasion of submucosa → mesenteric lymph nodes → potential bacteremia. Yersinia uses inv/ail genes to invade epithelial cells and resist phagocytosis.

281. Infectious mononucleosis differs from Yersiniosis by the presence of which clinical feature: Heterophile antibodies (positive Monospot test), atypical lymphocytes (Downey cells), pharyngotonsillitis with exudate, and EBV serology positivity in mononucleosis. Also: bilateral symmetrical cervical lymphadenopathy and tonsillar enlargement are prominent in mononucleosis but not yersiniosis.

282. The tetanus vaccine works by: a. Injecting inactivated toxins (toxoid) into the patient - tetanus vaccine contains tetanus toxoid (formaldehyde-inactivated tetanospasmin), which stimulates production of antitoxin antibodies without causing disease.

283. 21-year-old, multiple deep penetrating wounds, never vaccinated. Tetanus secondary prevention protocol: Administer both Tetanus Toxoid (TT/DT) AND Anti-Tetanus Serum (ATS 3,000 IU) or Human Tetanus Immunoglobulin (HTIG 250-500 IU) simultaneously at different sites. Then complete the primary vaccination series (3 doses of TT at 0, 4 weeks, 6 months). This provides immediate passive immunity (ATS/HTIG) plus active immunization (TT).

284. 37-week pregnant woman with no prior antenatal visits. Best approach for tetanus immunization: Administer two doses of Tetanus Toxoid (TT2) - give the first dose immediately (TT1) and second dose at least 4 weeks later (but before delivery). Even a single dose provides some protection to both mother and neonate. If she has prior vaccination history, give a booster dose.

285. Rash description in intestinal yersiniosis: Scarlatiniform (scarlet fever-like) or maculopapular rash on the trunk and extremities, appearing on days 3-6 of illness, followed by desquamation. Can resemble scarlet fever or measles rash.

286. Watery/mucoid diarrhea (78-96%), fever (43-47%), abdominal pain, bloody stools (<10%), leukocytes in stool, duration 1 day-3 weeks. Yersinia species: Yersinia enterocolitica - this is the typical presentation of Y. enterocolitica gastroenteritis, the most common cause of enteric yersiniosis. Y. pseudotuberculosis more commonly causes mesenteric lymphadenitis with less prominent diarrhea.

287. Student, 27 years, hyperemia/swelling/itching at scars on right forearm (bitten by dog-fox 3 months ago). Day 2: fever 38°C, intoxication, hydrophobia, photophobia, fear, paroxysms of cramps. Preliminary diagnosis: Rabies - the history of bite by a fox (3 months ago), prodromal symptoms at the scar site (hyperesthesia, itching), followed by hydrophobia, photophobia, fear, and convulsive paroxysms is pathognomonic for rabies. Incubation period of 3 months is within the typical range.

288. 22-year-old patient, weakness, dizziness, vomiting, insomnia, chills, fever, acute pain in right iliac region. Day 2. Impaired consciousness, excitation, weak cardiac sounds, tachycardia, weak pulse. Splenomegaly. Right iliac region: painful conglomerate of enlarged lymph nodes, dense/elastic, hyperemic skin. Works as a longshoreman in port. Clinical diagnosis: Plague, bubonic form - the right iliac bubo (conglomerate of dense, painful, enlarged lymph nodes with hyperemic overlying skin), severe systemic toxicity, impaired consciousness, splenomegaly, and occupation as a longshoreman (port worker with rat exposure) strongly suggest bubonic plague.

289. Person rested on lake bank, 6 days later: fever 38.5°C, headache, myalgia, sweating, then 3 days later: painful swelling in inguinal area. Dense, mobile, painful lymph nodes of 5 cm without skin changes. Most credible diagnosis: Tularemia (ulceroglandular or bubonic form) - the incubation period of 6 days after water/wildlife contact, systemic symptoms, then inguinal bubo (dense, mobile, without skin changes - unlike plague where skin is hyperemic). The absence of skin changes over the bubo and mobility are characteristic of tularemia bubo.

290. Same as Q7 - who should receive AC-Antitoxin + AC IP after trauma: d. Retired man of 57 years, who is not vaccinated - requires both toxoid and antitoxin for passive-active immunization.

291. Minimum duration of induction therapy for NTM in HIV patients: At least 12 months (same as Q186 - minimum 12 months, with some recommending continuation until sustained immune reconstitution on ART with CD4 >100 cells/μL for ≥6 months).

292. Pathogen causing scrub typhus: Orientia tsutsugamushi (formerly Rickettsia tsutsugamushi) - an obligate intracellular bacterium in the family Rickettsiaceae.

293. Scrub typhus is transmitted by which vector: Larval trombiculid mites (chiggers) - specifically the larvae of Leptotrombidium deliense and related species. The larva (chigger) is the only infectious stage.

294. Characteristic clinical feature of scrub typhus: Eschar (tache noire) at the chigger bite site - a painless, necrotic lesion with a black center and erythematous halo, found in skin folds, groin, axillae. Also: regional lymphadenopathy + fever + rash (macular, appearing around day 5).

295. Organ systems most commonly involved in scrub typhus: Multiple systems: lungs (interstitial pneumonitis, ARDS), liver (hepatitis - elevated transaminases), CNS (meningoencephalitis), cardiovascular (myocarditis), kidneys (AKI). The reticuloendothelial system (splenomegaly, lymphadenopathy) is also prominently involved.

296. Best description of the "epidemiological tetrad" of scrub typhus: b. Rodent - chigger mite - environment - human - wild rodents are the reservoir hosts; chigger mite larvae are the vector; the environment (scrub vegetation, transitional habitat) plays a key role; humans are accidental hosts entering the endemic environment.

297. Regions included in the "Tsutsugamushi triangle" (endemic area of scrub typhus): Asia-Pacific region bounded by: Pakistan/Afghanistan (northwest), Japan (northeast), Australia (south), and Siberia/Russia (north). Includes: India, Southeast Asia (Thailand, Philippines, Indonesia, Vietnam), China, Japan, Korea, Pacific islands, and northern Australia.

298. Most characteristic feature of cutaneous anthrax: Painless black eschar (malignant pustule) with surrounding non-pitting gelatinous edema - same as Q4, Q35.

299. Main pathogenic factor of Bacillus anthracis: Anthrax toxin complex (tripartite toxin): Protective Antigen (PA) + Lethal Factor (LF) = Lethal Toxin (LeTx); PA + Edema Factor (EF) = Edema Toxin (EdTx). Also the poly-D-glutamic acid capsule (anti-phagocytic). The toxins are the primary virulence factors causing cell death and edema.

300. Virulence factor of Bacillus anthracis that inhibits phagocytosis: Poly-D-glutamic acid capsule - the anthrax capsule is composed of poly-D-glutamic acid (encoded by pXO2 plasmid), which is anti-phagocytic and allows bacteria to evade innate immune clearance. (Note: the toxins are also anti-phagocytic but the capsule is the primary anti-phagocytic structure.)