[HBs antigen in rural population of Senegal (author's transl)].

The prevalence of HBs Ag has been determined by counter-immuno-electrophoresis among 16,006 Africans of all ages and both sexes living in 132 villages chosen at random in whole Senegal. 8,83 +/- 0,5 p. 100 of the examined people were positive for HBs Ag. HBs Ag is much more frequent among males (11,1 p. 100) than females (7,0 p. 100). Almost non existent before the age of 1, prevalence increases during childhood and reaches its summit between 10 and 14 years for boys (14,7 p. 100) and between 20 and 24 for women (10,1 p. 100), then it decreases regularly with old age and become negligible over 60. Ethnic factors and way of living are more important than geographical factors. Subtyping demonstrated the importance of contamination inside families and consequently the preponderance of oral over percutaneous transmission.