Seroepidemiology of human T-cell lymphotropic virus type I/II in Benin (West Africa)

Abstract

In 1988-1989, a national survey was conducted in Benin to determine the distribution of HTLV-I infection in a representative sample of adult individuals. This study comprised 2625 healthy subjects recruited in the six provinces of Benin and 1300 blood donors from Cotonou and from the other five provinces. Sera were screened for HTLV-I antibody by both immunofluorescence (IF) and enzyme immunoassay (EIA). Sera positive or doubtful by at least one technique were further analyzed by Western blot and radioimmunoprecipitation assay (RIPA) when indeterminate. Samples were considered as positive if they reacted with two gene products. No blood donor was positive. Over the 2625 subjects, 39 (1.5%) were positive. We observed a statistical difference between male and female (1%, 2%, p less than 0.05). A difference was also observed according to the areas studied: the HTLV-I antibody rate increased from coastal (0.3%) to northern (5.4%) provinces. HTLV-I seroprevalence increased significantly with age. This survey shows that HTLV-I infection exists in Benin but varies according to regions.

PIP: Researchers enrolled 2625 15 years old healthy individuals from the general population and 1300 blood donors of Benin to determine the extent of HTLV-I infection in Benin. They followed the recommended laboratory techniques of the US Public Health Service Working Group (1988). No blood donors were HTLV-I seropositive. The sera of 1.5% of the general population sample tested positive for HTLV-I. This rate was comparable to other western African countries. A significantly higher percentage of females were seropositive than males (2% vs. 1%; p.05), especially among the rural population (2.6% vs. 0.6%). No significant difference in seroprevalence existed between urban and rural areas overall (1.3% vs. 1.7%) and between urban males and females (1.4% vs. 1.1%), however. Further HTLV-I seroprevalence increased significantly as one went from south to north (0.6% in the 3 south coastal provinces, 1.1% in the central province, and 3.2% in the 2 northern provinces; p.001). In fact, the northern province of Atakora had the highest HTLV-I seroprevalence rate (5.4%), especially among females (p.0005), and was significantly higher than the other provinces (p.001). Research have since begun in several villages in Atakora to detect possible clusters and analyze associations between HTLV-I seroprevalence and life style, environmental and geographic factors, and concomitant infections such as filariasis. Seroprevalence also increased with age. For example, 0.4% of males 30 years old had HTLV-I antibodies compared to 1.8% of those 30 years old (p.02). In addition, 0.4% of females 20 years old had HTLV-I antibodies compared to 2.4% of those 30 years old (p.05). The researchers noted that other epidemiologic studies in Benin have begun to assess the prevalence of tropical spastic paraparesis with or without the association of HTLV-I and adult T-cell leukemia.