Résumé
A case‐control study was performed in Libreville, Gabon, to determine whether a relationship can be established between the relatively high proportion of non‐Hodgkin lymphoma (NHL) among all cancer cases and the high seroprevalence rate of HTLV‐I observed, and to discover whether cases of adult T‐leukemia/lymphoma (ATLL) related to HTLV‐I exist in Gabon. From November 1987 to April 1989, a total of 32 patients with NHL were recruited; 6 were infants with Burkitt's lymphoma and 26 were adults with NHL. Each patient was matched with 2 asymptomatic controls for age, sex and ethnic group. HTLV‐I serology was done by ELISA and Western blot. Comparison of the groups was done by chi‐square analysis. None of the 6 infants with Burkitt's lymphoma and none of their controls had antibodies to HTLV‐I. Of the 26 patients with NHL, 7 (26.9%) had HTLV‐I antibodies. Among the 52 controls, the HTLV‐I rate was 13.4% (n = 7). There was no difference between cases and controls (Fisher's exact test, p = 0.16). Among the 26 NHL, 4 cases fitted the criteria of ATLL and were HTLV‐I‐positive; 3 others who were positive for HTLV‐I were a woman with lymphoblastic gastric NHL and 2 old men with an unclassified lymphoma. From the results of this limited series it is not possible to state that there is an association between NHL and HTLV‐I infection. Nevertheless, cases of ATLL related to HTLV‐I are reported from this area. Based on the HTLV‐I seroprevalence rates reported in Gabon, the estimated incidence rate of ATL among seropositive people in Gabon appears much lower than in Japan. Different explanations can be proposed, but under‐diagnosis of ATLL is probably one of the main factors.