Community prevalence of antibodies to human immunodeficiency virus in rural and urban Vellore, Tamil Nadu.

BACKGROUND Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) are becoming increasingly common in India. Currently, antenatal prevalence is a surrogate marker for HIV prevalence in the community. The association between antenatal and community prevalence of HIV needs to be validated so that estimates can be verified or adjusted appropriately. METHODS A probability proportional to size cluster survey was conducted in the Kaniyambadi block of Vellore district and in the urban wards of Vellore town to estimate the prevalence of antibodies to rubella from August 1999 to February 2000. All personal identifier data from the serum samples were removed to yield a collection for which only the age and sex were known. Estimation of antibodies to HIV in sera from individuals between 15 and 40 years of age, was carried out by one screening ELISA and the reactive sera were further subjected to a supplementary test. RESULTS We tested 1512 serum samples from subjects residing in rural areas and 1358 samples from those residing in urban areas. The seropositivity among rural samples was 0.66% and among urban samples 1.4%. The prevalence was almost equal among men and women and the youngest infected individual was 15 years old. CONCLUSION The prevalence of HIV during the period of study was similar to the national surveillance data for Tamil Nadu based on antenatal women. HIV prevalence differs in urban and rural Tamil Nadu, with urban areas having a higher burden of the disease.