Brucella

Brucella survives within reticuloendothelial macrophages, producing the relapsing fever pattern and the need for prolonged combination therapy; monotherapy leads to relapse rates above thirty per cent. Species and host: B. melitensis from goats and sheep is the most virulent and most common worldwide, B. abortus from cattle, B. suis from swine, and B. canis from dogs. Transmission is by ingestion of unpasteurized milk or soft cheese, inhalation, or direct contact with placental material and abattoir waste; brucellosis is an occupational disease of farmers, veterinarians, abattoir workers, and microbiology laboratory staff, and is a common laboratory-acquired infection. Clinically there is insidious fever with malodorous perspiration, malaise, weight loss, hepatosplenomegaly, and lymphadenopathy, and osteoarticular disease in up to half of patients, most often sacroiliitis, peripheral arthritis, and lumbar spondylitis. Liver biopsy shows non-caseating granulomas. Treatment is doxycycline plus rifampin, or doxycycline plus an aminoglycoside, for six weeks or longer.