Brucellosis


– Brucellosis is a zoonosis that mainly affects livestock animals. 
– The main routes of transmission to humans are: 
• digestive, by ingestion of unpasteurized milk (or unpasteurized milk products) from an infected animal;
• cutaneous, by direct contact with infected animals or carcasses of infected animals. 
– Brucellosis is caused by bacteria of the genus Brucella, particularly B. melitensis (sheep and goats), B. abortus (cattle), B. suis (pigs).
– The disease is found worldwide and mainly in rural areas. 
– After primary infection relapses may occur (5 to 15% of cases, even months after end of initial treatment) or the infection may become chronic.

Clinical features

Acute form (primary infection)
– Remittent or intermittent fever (39-40 °C), associated with several signs or symptoms: chills, night sweats, joint and muscle pain, weight loss, fatigue, malaise, headache; adenopathies (particularly in children).
– May be associated with: non-specific gastrointestinal disorders, cough, hepato and/or splenomegaly, arthritis (knee), orchitis.

Diagnosis is difficult because of the broad spectrum of fluctuating and non-specific clinical manifestations. In patients with unexplained fever, brucellosis should be considered when risks factors are present: consumption of unpasteurized milk products; exposure to livestock (e.g. livestock farmers, veterinarians, butchers, slaughterhouse workers).

Localised form 
Primary infection may progress to localised infection (even several months or years later), mainly:
• osteoarticular: sacroiliac joint and often particularly lower limbs joints;  spine (intervertebral disk infection, vertebral osteomyelitis)
• genito-urinary: orchitis, epididymitis 
• pulmonary: bronchitis, pneumonia, pleurisy 
• neurological : meningitis, encephalitis, polyneuritis

Paraclinical investigations

Laboratory
− Blood culture is the gold standard for diagnosis. It is positive only in the acute phase. The bacteria grow slowly (7 to 21 days).
– Serological tests (Rose Bengal, Wright agglutination test, indirect immunfluorescence, ELISA, etc.) provide presumptive diagnoses.
– In the event of neurological signs or meningitis, lumbar puncture shows clear cerebrospinal fluid (CSF) that may contain high white blood cell count; high protein concentration in CSF; low CSF glucose. 
– Rule out malaria in endemic regions (rapid test). 
– Exclude tuberculosis if cough > 2 weeks (sputum smear microscopy).

Radiography 
− Joint pain (hips, knees, ankles, vertebrae, sacroiliac joint): small erosions or destruction or joint space narrowing.
− Chest x-ray often normal; sometimes pleural effusion.

Treatment

Check national recommendations on antibiotic therapy. For information:

Children under 8 years

co-trimoxazole + rifampicin
or co-trimoxazole + gentamicin

Children 8 years and over

doxycycline + rifampicin
or doxycycline + gentamicin

Adults

doxycycline + rifampicin
or doxycycline + streptomycin or gentamicin

Pregnant/breast-feeding women

rifampicin

co-trimoxazole PO for 6 weeks
Children < 8 years: 20 mg SMX + 4 mg TMP/kg 2 times daily

doxycycline PO for 6 weeks
Children ≥ 8 years: 1 to 2 mg/kg 2 times daily
Adults: 100 mg 2 times daily

rifampicin PO for 6 weeks
Children: 15 to 20 mg/kg once daily (max. 600 mg daily)
Adults: 600 to 900 mg once daily

gentamicin IM for 2 weeks
Children and adults: 5 mg/kg once daily

streptomycin IM for 2 weeks
Adults: 1 g once daily

For localised forms of the infection, same treatment but for a period of 6 weeks to 4 months depending on the focus.

Prevention

– Washing of hands and clothing if in contact with animals.
– Boil milk, avoid ingestion of unpasteurized milk products, cook offal thoroughly.