[Epidemiology of human and animal brucellosis in western Africa. The results of six studies in the Ivory Coast, Upper Volta, and Nigeria].

Brucellosis has a two-fold importance in public health: the transmission of the disease to man by contact with animals or ingestion of raw milk is of direct importance; of indirect importance is the loss of animal protein. The authors have carried out ten epidemiological investigations in different bio-climatic zones of West Africa. More than 120 villages were evaluated. In each village, 100 persons were chosen at random and all or part of the animal population was also studied. Three tests were used for man: the melitin intradermal reaction, the sero-agglutination test of Wright and the complement fixation test. Three tests were used for the animals, the "ring-test" and the same serologic tests used for humans. The results indicated that brucellosis in animals exists in all regions but with varying rates. The bovine species seems to be the most contaminated. The enzooty becomes more widespread towards the South. Human brucellosis was not found to be of great importance in the regions mainly populated by farmers. Shepherds and their families in these zones, however, were found to have been infected. The highest percentage of infected humans was found in the sahelian zone (in Dori 30% of the intradermal reactions and 10% of serologies were positive for humans) in spite of a rather low infection rate among animals (6%-8% ring-tests positive among cattle). The majority of the population are shepherds and close cohabitation with animals is common. A basic dietary constituent is milk, which is often consumed raw (variable according to ethnic group), and provides the principal source of animal protein. Adults were found to have a significantly higher intradermal reaction rate in most of the regions studied. The positivity rate was higher in men than in women. In non-pastoral areas the shepherds and their families had a singificantly higher positivity rate than the general population. Ethnic differences were found. Also considered in this paper are intradermal reaction sizes, the relation between intradermal and serologic results, the modes of human transmission of the disease, and the relationship between human and animal forms of brucellosis.