Asymptomatic Brucella bacteraemia and isolation of Brucella melitensis biovar 3 from human breast milk.

Brucellosis is a zoonotic disease and virtually all infections derived from exposure to animals or ingestion of unpasteurized dairy products. Brucellosis among family members has been reported. However, screening household members of an index case of acute brucellosis is not a routine procedure. A 10-y-old boy was diagnosed with acute brucellosis. Unpasteurized goat cheese commonly consumed within the family was thought to be the possible source of the bacteria. The family (parents, sister and brother) was screened with physical examination, serum tube agglutination test, blood cultures and routine laboratory tests. Three additional cases (parents and sister) of serological and culture proven brucellosis were detected. Two of them (mother and sister) were asymptomatic and had no clinical findings. Brucella melitensis biovar 3 was isolated from breast milk culture and from all blood cultures of 4 brucellosis cases. In conclusion, brucellosis, even with bacteraemia, can be completely asymptomatic. Consumption of raw milk products by household members is a common risk factor for brucellosis outbreak among family members. Thus, screening household members of an index case of brucellosis can expose new brucellosis cases.