Clustering of human T lymphotropic virus type 1 seropositive in Montserrat, West Indies: evidence for an environmental factor in transmission of the virus

ABSTRACT

A community survey of human T cell lymphotropic virus type I (HTLV-I) in Montserrat, West Indies, identified 22 instances in which 2 HTLV-I-seropositive adults lived within 60 m of each other (close pairs), compared with 7.8 expected (P<.001). Five of these close pairs were mother offspring or husband-wife. The remaining 17 pairs were of unrelated members in separate households. The percentages of male-female (41 percent), female-female (41 percent), and male-male (18 percent) types in these 17 pairs were similar to those among the 1377 similarly defined pairs in which neither or only 1 member was seropositive, affording no support for extramarital heterosexual activity as an explanation for the clustering observed. Thus, the demography of HTLV-I was not accounted for completely by sexual and mother-to-offspring tranmission. The predominace of clustering of unrelated HTLV-I-seropositive individuals in locations with high mosquito infestation raised the possibility of sporadic transmission of HTLV-I by hematophagous insects (AU)