The epidemiology of HIV in India

Abstract

India is the first country outside Africa where an HIV-2 epidemic is running in parallel to an HIV-1 epidemic, resulting in a significant proportion of double infections. HIV is spreading rapidly, mainly by heterosexual contact, but also among intravenous drug users. Genetic analyses of the HIV variants circulating in India point towards HIV-1 and HIV-2 having been introduced into the country recently.

PIP: The genetic strains of HIV which have been uncovered in India have a different origin from those present in Thailand. Also, both HIV-1 and HIV-2 have been detected in India. In a 1991-93 study of clients of a sexually transmitted disease clinic in Bombay, it was found that seroprevalence of HIV in 241 clients was 39%, the 78.5% positive for HIV-1, 6.5% for HIV-2, and 15% for both. Distribution was even for males and females, reflecting heterosexual transmission. HIV-2 has also been detected in other parts of India, and HIV-1 is spreading throughout the country. HIV in children is a sequelae to blood transfusion. The prevalence of HIV in areas where IV drug use is rampant is increasing rapidly and is spreading to the general population. Genetic analysis revealed that the most closely related genetic sequence to the Indian HIV-1 from Bombay occurs in a strain of the virus from South Africa. One subtype of HIV-2 and several subtypes of HIV-1 have been found, with HIV-1 subtype C and HIV-2 subtype A the most frequently encountered. An examination of phylogenetic trees shows the relationships among these different strains. The close genetic relationship between isolates of HIV-1 and HIV-2 from patients in different parts of the country reflects the recent introduction of these strains. Thus, India is an ideal site for studying the efficacy of a vaccine designed specifically for a population of highly similar strains (the high similarity among HIV-2 isolates is unique in India). Since HIV-2 strains are diverging at a rate of 1% per year, any such research would have to occur soon.