HTLV-1 and dengue seropositivity in Montserrat - abstract

Over 80 percent of the adult population of three villages in Montserrat donated blood samples for screening for HTLV-I and dengue antibodies. Twenty-five (7.2 percent) of the 349 samples tested were positive for HTLV-I antibodies and 17 of them live in 4 clusters of neighbouring households which was statistically significant. This clustering was not primarily due to viral or mother-to-child transmission but was the result of related and unrelated seropositive individuals living near to each other far more frequently than by chance alone. Two hundred and two (61 percent) of 331 samples tested were seropositive for dengue. Dengue seropositivity prevalence rates increased markedly with age and showed a strong difference in prevalence by altitude. This high prevalence of dengue seropositivity was surprising since no epidemics of dengue fever were reported in Montserrat. There is no evidence to support the hypothesis that the same insect vectors have a role in both dengue and HTLV-I transmission. However, the clustering observed, the inverse relation between HTLV-I sero prevalence and altitude and the failure of HTLV-I to establish itself in temperate climates, justify the need for further studies (AU)

Human T-lymphotropic virus type I (HTLV-I) seroprevalence in Jamaica - II geographic and ecological determinants

An island-wide cohort of 13,260 Jamaicans who applied for food-handling licenses during 1985 and 1986 were tested for antibodies to human T-cell lymphotropic virus type I (HTLV-I). Demographic and residence history data were linked to geographic measures of elevation, rainfall, crop-growing areas, population density, and additional measures of urbanization and correlated with HTLV-I antibody status. By logistic regression analysis (performed separately for men and women), men and women who currently resided at low elevation (ó1,000 ft (305 m)) were more likely to be HTLV-infected than were those residing at high elevation. Men, but not women, who were born in citrus-growing areas were more likely to be HTLV-I infected than were men who were born in other areas. By univariate analysis, there was a significant positive trend of increasing HTLV-I seroprevalence with increasing amount of annual rainfall associated with birthplace and primary residence areas. However, these associations did not remain in significance after adjusting for age and sex. These environmental associations raise the possibility of new modes of viral transmission or host response to infection, although they may simply be surrogates for socioeconomic status, breast-feeding habits, or sexual behaviour, which are known determinants of HTLV-I zero prevalence. (AU)