[Intra-family transmission of human T-cell lymphotropic virus-1 (HTLV-1) in a cohort of HTLV-1-positive patients (Bénin)].

We are reporting the results of a familial study carried out in Benin in March 1994 within a cohort of HTLV-1 positive subjects. This study aims at appraising the different modes of intra-familial transmission of this retrovirus. The study has included 212 persons: 33 seropositive subjects (identified during two previous seroprevalence surveys and followed up since 1991), and 179 members of their families. Blood specimens have been taken from each of these subjects. Sera have been screened for HTLV-1 antibodies by ELISA test and positive results confirmed by Western blot test. Out of 18 children born during the follow up period, 2 cases of seroconversion have been observed. One case of seroconversion has also been noted among the 17 couples in which either of the spouses is seropositive. Among the 136 children of the cohort: 17.8% of them are HTLV-1 positive when both parents are seropositive 26.1% if the mother only is seropositive and 0% if the father only is seropositive. The incidence rate in this cohort is estimated to be 0.43%. These data relative to the intra-familial transmission of HTLV-1 in Benin appear to be consistent with those previously reported in Japan.