Malaria: Diagnosis, Epidemiological Determinants, Complications & Prevention

a) Diagnosis

• Both thick film and thin film are prepared on a single glass slide.
• Thick film: More sensitive - detects scanty parasites ~20x faster; used to search for parasites.
• Thin film: Better species identification - parasites seen more clearly.
• Stain used: Leishman stain or Giemsa stain.
• Limitation: Requires trained microscopist; time-consuming.

• Based on symptoms: fever with intermittent periodicity (48 hrs for P. vivax/P. falciparum; 72 hrs for P. malariae), splenomegaly, anaemia.
• Three stages of febrile paroxysm: Cold stage → Hot stage → Sweating stage.
• As per revised drug policy 2013, presumptive treatment alone is no longer acceptable; parasitological confirmation is mandatory.

• Based on detection of circulating parasite antigens using a simple dipstick format.
• Some kits detect P. falciparum only; others detect multiple species (but are expensive and temperature-sensitive).
• Useful in field settings where microscopy is unavailable.
• Important: Always read user manual to avoid false-negative results.

b) Epidemiological Determinants

Agent Factors

• Causative organism: Plasmodium species - P. falciparum, P. vivax, P. ovale, P. malariae
• P. falciparum is most dangerous and prone to complications
• Gametocytes (infective stage to mosquito): appear 4-5 days post-asexual parasites in vivax; 10-12 days in falciparum
• Drug resistance: P. falciparum is resistant to chloroquine and sulfadoxine-pyrimethamine in most endemic areas → necessitating Artemisinin-based Combination Therapy (ACT)

Host Factors

• Age: Affects all ages; newborns have relative resistance due to fetal haemoglobin (suppresses P. falciparum)
• Sex: Males more exposed due to outdoor life
• Race/Genetics:
  • Sickle-cell trait (AS haemoglobin) - protective against P. falciparum
  • "Duffy-negative" individuals - resistant to P. vivax
• Pregnancy: Increases risk; may cause intrauterine death, premature labour, abortion; primigravidae most at risk
• Immunity: Repeated infections build partial immunity
• Socio-economic status: Malaria has declined in developed countries with economic development
• Housing: Ill-ventilated, ill-lit houses favour indoor resting of mosquitoes

Environmental/Vector Factors

• Vector: Female Anopheles mosquito (over 60 species implicated)
• Breeding sites: Stagnant, clean water - pools, ponds, rice fields, construction sites
• Temperature: Optimal 20-30°C; sporogony (parasite development in mosquito) ceases below 16°C
• Rainfall and humidity: Promotes mosquito breeding
• Season: Transmission peaks post-monsoon in India (August-November)
• Geography: Forest, forest-fringe, tribal areas have highest burden in India; northeastern states, Chhattisgarh, Jharkhand, Odisha, MP, Maharashtra account for ~91% of cases and 99% of deaths in India

c) Complications

P. falciparum Complications (Severe/Complicated Malaria)

P. vivax / P. ovale / P. malariae Complications

• Anaemia
• Splenomegaly (can lead to splenic rupture)
• Hepatomegaly
• Herpes labialis (febrile herpes)
• P. malariae - nephrotic syndrome (quartan malarial nephropathy), chronic low-grade parasitaemia lasting 40+ years

d) Prevention

1. Personal Prophylaxis (Individual Protection)

• Chemoprophylaxis: Chloroquine (where sensitive) for travelers/high-risk groups; Doxycycline or Mefloquine for resistant areas
• Insect repellents: DEET-based repellents on exposed skin
• Protective clothing: Long sleeves, long pants, especially at dusk/dawn
• Bed nets: Insecticide-Treated Bed Nets (ITNs) / Long Lasting Insecticidal Nets (LLINs)
• Window/door screening

2. Vector Control

• Indoor Residual Spraying (IRS): DDT, Malathion, synthetic pyrethroids sprayed on indoor walls - kills mosquitoes resting on treated surfaces
• Larval control (Anti-larval measures):
  • Source reduction: eliminating breeding sites (draining stagnant water, filling depressions)
  • Larviciding: Paris green, petroleum oils, temephos (Abate)
  • Biological control: Gambusia fish (larva-eating fish), Bacillus thuringiensis israelensis (Bti)
• Environmental management: Drainage of swamps, proper irrigation management, solid waste disposal

3. Case Detection and Treatment (Surveillance)

• Passive case detection: Fever cases reporting to health facilities tested and treated promptly
• Active case detection: Health workers visit households in high-risk areas
• Radical treatment: Complete treatment (primaquine for P. vivax to kill hypnozoites and prevent relapse)
• Sentinel surveillance

4. Health Education and Community Participation

• Awareness about mosquito breeding prevention
• Proper use of bed nets
• Seeking early treatment for fever

5. Epidemic Preparedness

• Stock-piling of drugs, insecticides, RDTs
• Rapid response teams

6. Malaria Vaccines

• RTS,S/AS01 (Mosquirix): First licensed malaria vaccine (WHO recommended 2021); targets P. falciparum; partial efficacy (~30-50%)

✅ What You Have (Already Correct & Relevant)

➕ What You Should ADD for a Complete 10-Mark Answer

1. Personal Chemoprophylaxis

• Chloroquine 300 mg base weekly (where sensitive) - start 1 week before, continue 4 weeks after leaving endemic area
• Doxycycline / Mefloquine for chloroquine-resistant areas

2. Early Diagnosis and Prompt Treatment

• Thick & thin smear / RDT for all fever cases
• Radical cure: Primaquine for P. vivax (kills hypnozoites, prevents relapse)
• Prevents onward transmission by clearing gametocytes

3. Health Education

• Avoid outdoor exposure at dusk and dawn (peak biting time)
• Use of full-sleeved clothing
• Community participation in source reduction

4. Malaria Vaccine (add 1 line)

• RTS,S/AS01 (Mosquirix) - WHO recommended (2021) for P. falciparum in children

5. National Programme

• NVBDCP (National Vector Borne Disease Control Programme) - oversees malaria control in India

How to Structure Your Answer

Prevention of Malaria
├── A. Mosquito Control (your notes - already excellent)
│     ├── Anti-larval measures
│     ├── Anti-adult measures  
│     └── Protection against bites
├── B. Chemoprophylaxis (ADD this)
└── C. Health Education + NVBDCP (ADD briefly)

d) Prevention of Malaria

1. Mosquito Control Measures
2. Chemoprophylaxis
3. Early Diagnosis and Treatment
4. Health Education and National Programme

1. Mosquito Control Measures

A) Anti-Larval Measures

a) Environmental Control

• Source reduction - filling, levelling, drainage of breeding places and water management such as intermittent irrigation
• Changing salinity of water
• Culex - abolition of cesspools and open ditches; adequate collection and removal of sewage water
• Aedes - discard waters holding containers like discarded tins
• Anopheles - filling and drainage of breeding places

b) Chemical Control

• Mineral oils: crude oil, kerosene, larvicide oils (spread on water surface - suffocate larvae)
• Paris green: stomach poison for larvae
• Synthetic insecticides: Fenthion, Chlorpyrifos

c) Biological Control

• Gambusia affinis fish
• Lebistes reticulatus fish (These fish feed on mosquito larvae)

B) Anti-Adult Measures

a) Residual Sprays

• DDT
• Malathion
• Gamma HCH (Lindane)

b) Space Sprays

• Pyrethrum extract - nerve poison; temporary reduction
• Residual insecticides - Malathion, Fenithothion

c) Genetic Control

• Sterile male technique
• Cytoplasmic incompatibility

C) Protection Against Mosquito Bites

• DEET (Diethyl toluamide) - most effective
• Dimethyl phthalate (DMP)
• Applied on exposed parts of body

2. Chemoprophylaxis

• Start 1 week before entering endemic area
• Continue 4 weeks after leaving the area
• Primaquine given for radical cure of P. vivax to kill hypnozoites and prevent relapse

3. Early Diagnosis and Prompt Treatment

• All fever cases tested by thick/thin smear microscopy or RDT
• Prompt treatment with ACT (Artemisinin-based Combination Therapy) for P. falciparum
• Radical treatment with primaquine for P. vivax prevents relapse and breaks transmission
• Aims: complete cure, prevent complications, interrupt transmission, minimize drug resistance

4. Health Education and National Programme

• Avoid outdoor exposure at dusk and dawn (peak mosquito biting time)
• Wear full-sleeved clothing
• Community participation in source reduction (remove stagnant water near homes)
• NVBDCP (National Vector Borne Disease Control Programme) - nodal programme for malaria control in India
• Strategies: Surveillance, Integrated Vector Management, Epidemic preparedness
• Malaria Vaccine: RTS,S/AS01 (Mosquirix) - WHO recommended (2021) for P. falciparum in children; partial efficacy ~30-50%

Tip for exam: In 10-mark answer, mosquito control measures carry the most marks - your notes on that part are very detailed and accurate. Write all 3 parts (anti-larval, anti-adult, protection against bites) with subpoints as above.