Categories
Internal Medicine

Brucellosis

Introduction

Relatively uncommon chronic granulomatous infection which is often missed or misdiagnosed as tuberculosis.

  • AKA, undulant feverMalta fever and Mediterranean fever
  • Zoonosis 

History


Epidemiology

Worldwide prevalence

  • Preferred hosts:
    • Sheep and goats: B. melitensis
    • Cattle: B. abortus
    • Pigs: B. suis
    • Dogs: B. canis
  • Transmission:
    • Consumption of:
      • Infected unpasteurized milk
      • Animal products
    • Direct contact:
      • Infected animal parts (eg. placenta)
    • Inoculation of skin and mucous membranes
    • Inhalation of infected aerosolized particles
journal.pmed.0040317.g001
The Global Incidence of Human Brucellosis | Reproduced from: Gutierrez Ruiz C, Miranda JJ, Pappas G (2006) A 26-year-old man with sternoclavicular arthritis. PLoS Med 3(8): e293. doi:10.1371/journal.pmed.0030293 Derived from: Pappas G, Papadimitriou P, Akritidis N, Christou L, Tsianos EV (2006) The new global map of human brucellosis. Lancet Infect Dis 6: 91-99.

Clinical Features

Presentations:

  • Acute illness (<2 months),
  • Subacute illness (2-12 months)
  • Chronic illness (>1 yr)

Incubation period: 7 days – 3 months

  • Fever
    • Continuous/intermittent
    • Persist for several months
    • Accompanied by:
      • Profuse sweating
      • Joint pains (M/C, knee)
      • Hepatosplenomegaly
      • (rare) Lymphadenopathy

Complications

  • Spondylitis
  • Osteoarthritis
  • Meningoencephalitis
  • Brain abscess
  • Pneumonia
  • Endocarditis

Diagnosis

Investigations

Complete blood count (CBC):

  • Anaemia
  • Leukopenia
  • Thrombocytopenia

Liver enzymes

  • Mildly elevated (SAP & GGT > transaminases)

Culture

  • Blood culture (GOLD STANDARD)
    • Good sensitivity if done prior to antibiotic therapy and specimen incubated for 4 weeks
  • Bone marrow cultures
    • Higher sensitivity since organisms are present in large amounts in the reticuloendothelial system.

Serologic diagnosis

  • Serum agglutination test
    • Titers > 1:160 or 1: 320 diagnostic
  • ELISA (IgG and IgM antibodies)

Differentials

  • Tuberculosis
  • Enteric fever
  • Chronic malaria
  • HIV
  • Sarcoidosis
  • Lymphoproliferative disorders

Management

Combination therapy (for 6 weeks)

As all monotherapies and short treatments are characterized by unacceptably high relapse rates.

  • Standard regimen:
    • Doxycycline + streptomycin (first 3 weeks)
    • Doxycycline + rifampicin (next 3 weeks)
  • Children < 8 yr age:
    • Rifampicin + TMP-SMZ ± aminoglycosides
  • Treatment is prolonged for,
    • Endocarditis
    • Neurobrucellosis

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