Brucellosis

KEY FEATURES

Essentials of Diagnosis

• History of animal exposure, ingestion of unpasteurized milk or cheese

• Insidious onset

  • Fatigability

  • Headache

  • Arthralgia

  • Anorexia

  • Sweating

  • Irritability

• Intermittent or persistent fever, especially at night

• Cervical and axillary lymphadenopathy; hepatosplenomegaly

• Lymphocytosis, positive blood culture, positive serologic test

General Considerations

• The infection is transmitted from animals to humans. Brucella abortus (cattle), Brucella suis (hogs), Brucella melitensis (goats, sheep, camels), and Brucella canis (dogs) are the main agents

• Transmission to humans occurs by

  • Contact with infected meat (slaughterhouse workers)

  • Placentas of infected animals (farmers, veterinarians)

  • Ingestion of infected unpasteurized milk or cheese

• The incubation period varies from a few days to several weeks

• May become chronic

Demographics

• In the United States, brucellosis is very rare except in visitors or immigrants from countries where brucellosis is endemic (including Mexico, Mediterranean Europe, the Middle East, and South and Central American countries)

CLINICAL FINDINGS

Symptoms and Signs

• Insidious onset of

  • Weakness

  • Weight loss

  • Low-grade fevers

  • Sweats

  • Exhaustion with minimal activity

• Headache

• Abdominal or back pains with anorexia and constipation

• Arthralgia

• Hepatosplenomegaly

• Lymphadenopathy

• Chronic form

  • May assume an undulant nature, with periods of normal temperature between acute attacks

  • Symptoms may persist for years, either continuously or intermittently

• Infection may present with or be complicated by specific organ involvement, with signs of endocarditis, meningitis, epididymitis, orchitis, arthritis (especially sacroiliitis), spondylitis, or osteomyelitis

Differential Diagnosis

• Should differentiate from other acute febrile disease, especially

  • Influenza

  • Tularemia

  • Q fever

  • Infectious mononucleosis

  • Enteric fever

• In its chronic form, brucellosis resembles

  • Hodgkin disease

  • Tuberculosis

  • HIV infection

  • Malaria

  • Disseminated fungal infections (eg, histoplasmosis, coccidioidomycosis)

DIAGNOSIS

Laboratory Tests

• The organism can be recovered from cultures of the

  • Blood

  • Cerebrospinal fluid

  • Urine

  • Bone marrow

• Diagnosis is often made by serologic testing

• Cultures are more likely to be negative in chronic cases

TREATMENT

Medications

• Single-drug regimens are not recommended because relapse rate may be high

• Combination regimens of two or three drugs are more effective

• These regimens have the lowest recurrence rates for non-localizing disease

  • Doxycycline, 100 mg orally twice daily for 6 weeks plus

  • Rifampin, 600–900 mg/day orally for 6 weeks or

  • Streptomycin, 1 g/day intramuscularly or intravenously for the first 14–21 days or

  • Gentamicin, 5 mg/kg intramuscularly or intravenously once daily for 7 days

• Longer courses of therapy (eg, several months) and/or additional antibiotics may be required to prevent relapse of meningitis, osteomyelitis, or endocarditis

OUTCOME

Complications

Most frequent

• Bone and joint lesions such ...