What are sign and symptoms of brucellosis

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Signs and Symptoms of Brucellosis

Source: Goldman-Cecil Medicine (International Edition) & Firestein & Kelley's Textbook of Rheumatology

Overview

Brucellosis (also historically called Malta fever, Mediterranean fever, or undulant fever) is a systemic zoonotic infection caused by Brucella species. It has protean (highly variable) manifestations, and virtually any organ system can be involved. The incubation period is typically 2-4 weeks from infection to bacteremia, though it can range from 1 week to several months.

Acute Brucellosis - General Symptoms

The onset can be abrupt or insidious. Classic features include:
SymptomNotes
FeverThe hallmark feature - often the distinctive "undulant" (wave-like) pattern in subacute/chronic disease. Can be continuous, remittent, or intermittent.
Profuse sweatingEspecially nocturnal; classically described as having a "wet hay" or musty odor
Malaise & fatigueOften profound and debilitating
HeadacheFrequently reported, can be severe
Arthralgia / myalgiaJoint and muscle pain, very common
Back painEspecially lumbar; may indicate spondylitis
Anorexia and weight lossCommon in prolonged illness
DepressionPsychiatric involvement is recognized
ChillsAccompany the febrile episodes

Physical Examination Findings (Signs)

  • Hepatomegaly - liver enlargement, found in up to 40-70% of patients
  • Splenomegaly - enlarged spleen, very common (up to 20-30%)
  • Lymphadenopathy - generalized or regional swelling of lymph nodes
  • Hepatosplenomegaly - combined liver and spleen enlargement is a classic sign
  • Tenderness over the spine - suggests vertebral osteomyelitis/spondylitis
  • Joint swelling and tenderness - in cases with arthritis
  • Skin rash - occurs in a minority (~5%) of cases; various forms described (maculopapular, purpuric, nodular, vasculitic)

Focal / Organ-Specific Manifestations

Focal disease occurs in approximately 30% of patients:

1. Osteoarticular (Most Common Focal Complication - ~60-70% of focal cases)

  • Sacroiliitis - extremely painful; most common articular site in adults
  • Spondylitis / vertebral osteomyelitis - most commonly lumbar spine; can cause epidural abscess
  • Peripheral arthritis - monoarthritis or oligoarthritis; knee and hip most affected (especially in children)
  • Bursitis and tenosynovitis - less common

2. Genitourinary

  • Orchitis / epididymo-orchitis - swollen, tender testicle; occurs in ~2-20% of men with brucellosis; can mimic testicular torsion or tumor
  • Pyelonephritis, glomerulonephritis - renal involvement
  • Prostatitis

3. Neurological (Neurobrucellosis - ~1-5% of cases)

  • Meningoencephalitis - headache, stiff neck, altered consciousness
  • Radiculopathy / peripheral neuropathy
  • Myelitis
  • Cranial nerve palsies
  • Psychiatric manifestations - depression, psychosis
  • A 2024 systematic review and meta-analysis (PMID: 35930502) confirmed meningitis/meningoencephalitis as the dominant neurobrucellosis presentation

4. Cardiovascular (Rare but Serious)

  • Endocarditis - most feared complication; accounts for most brucellosis-related deaths; typically affects the aortic valve
  • Myocarditis, pericarditis
  • Arterial aneurysms

5. Pulmonary

  • Pneumonia, pleuritis, pleural effusion, lung abscess - less common
  • Inhalation is an important occupational route of infection (lab workers, slaughterhouse workers)

6. Hepatic

  • Granulomatous hepatitis - liver granulomas are common pathological findings
  • Jaundice - in cases with significant liver involvement
  • Liver abscess - rare

7. Ocular

  • Uveitis (anterior or posterior), optic neuritis, and keratitis (noted in Kanski's Clinical Ophthalmology)

8. Hematological

  • Thrombocytopenia - low platelet count, can cause bleeding
  • Leukopenia - low white cell count
  • Anemia
  • Hemophagocytic lymphohistiocytosis (HLH) - a rare but serious complication (reported in 2024, PMID: 38663334)

Disease Phases

PhaseDurationKey Features
Acute< 2 monthsFever, sweats, malaise, hepatosplenomegaly
Subacute2-12 monthsUndulant fever, focal complications begin
Chronic> 12 monthsFatigue, depression, focal disease (endocarditis, spondylitis, neurobrucellosis); can be difficult to treat

Key Clinical Pearls

  • The undulant fever pattern (fever waxing and waning over weeks) is classic but not always present
  • Night sweats with a characteristic musty odor are a distinguishing feature
  • Brucellosis should be suspected in anyone with prolonged fever + osteoarticular pain + exposure history (livestock, unpasteurized dairy, travel to endemic regions)
  • Orchitis in a young man from an endemic area should raise suspicion
  • Laboratory findings often show leukopenia, mild anemia, and elevated ESR/CRP; liver enzymes are often mildly elevated

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