HIV This Week

Dandona L, Lakshmi V, Sudha T, Kumar GA, Dandona R. A population-based study of human immunodeficiency virus in south India reveals major differences from sentinel surveillance-based estimates. BMC Med 2006;4:31.

The HIV burden among adults in India is estimated officially by direct extrapolation of annual sentinel surveillance data from public-sector antenatal and sexually transmitted infection (STI) clinics and some high-risk groups. The validity of these extrapolations has not been systematically examined with a large sample population-based study. Dandona and colleagues sampled 13 838 people, 15-49 years old, from 66 rural and urban clusters using a stratified random method to represent adults in Guntur district in the south Indian state of Andhra Pradesh. The authors interviewed the sampled participants and obtained dried blood spots from them, and tested blood for HIV antibody, antigen and nucleic acid. They then calculated the number of people with HIV in Guntur district based on these data, compared it with the estimate using the sentinel surveillance data and method, and analysed health services use data to understand the differences. In total 12,617 people (91.2%) gave a blood sample. Adjusted HIV prevalence was 1.72% (95% CI 1.35-2.09%); men 1.74% (1.27-2.21%), women 1.70% (1.36-2.04%); rural 1.64% (1.10-2.18%), urban 1.89% (1.39-2.39%). HIV prevalence was 2.58% and 1.20% in people in the lower and upper halves of a standard of living index (SLI). Of women who had become pregnant during the past 2 years, 21.1% had used antenatal care in large public-sector hospitals participating in sentinel surveillance. There was an over-representation of the lowest SLI quartile (44.7%) in this group, and 3.61% HIV prevalence versus 1.08% in the remaining pregnant women. HIV prevalence was higher in that group even when women were matched for the same SLI half (lower half 4.39%, upper 2.63%) than in the latter (lower 1.06%, upper 1.05%), due to referral of HIV-positive/suspected women by private practitioners to public hospitals. The sentinel surveillance method (HIV prevalence: antenatal clinic 3%, STI clinic 22.8%, female sex workers 12.8%) led to an estimate of 112,635 (4.38%) people with HIV, 15-49 years old, in Guntur district, which was 2.5 times the 45,942 (1.79%) estimate based on this population-based study. The authors conclude that the official method in India leads to a gross overestimation of the HIV burden in this district due to addition of substantial extra HIV estimates from STI clinics, the common practice of referral of HIV-positive/suspected people to public hospitals, and a preferential use of public hospitals by people in lower socioeconomic strata. India may be overestimating its HIV burden with the currently used official estimation method.

Editors’ note: This kind of study can be extremely valuable in increasing the precision of estimates at local level and in helping understand the possible sources of variance at state (or province), regional and national level.

Smolskaya T, Liitsola K, Zetterberg V, Golovanova E, Kevlova N, Konovalova N, Sevastianova K, Brummer-Korvenkontio H, Salminen M. HIV epidemiology in the Northwestern Federal District of Russia: dominance of HIV type 1 subtype A. AIDS Res Hum Retroviruses 2006;22:1074-80.

A rapidly advancing epidemic of HIV-1 infection has been documented among people who inject drugs in Russia. The Northwestern Federal District was the first of the seven Russian Federal Districts involved in a drug-related HIV epidemic through an outbreak in Kaliningrad in 1996. The Northwestern Federal District has a high HIV prevalence rate having reached 252 per 100,000 by the end of 2003, exceeding the Russian average (180) by 1.4 times. The epidemic peaked in 2001. Since then the annual number of new cases has decreased, probably reflecting saturation among at least some IDU populations. However, at the same time, the heterosexual spread of HIV has become more prominent. To study the genetic epidemiology of HIV-1, Smolskaya and colleagues collected samples from 150 individuals covering a wide geographical area and different transmission groups in the Northwestern Federal District. Phylogenetic analysis revealed that an Eastern European subtype A HIV-1 strain similar to those reported earlier among people who inject drugs in other regions of Russia accounted for 80% of HIV-1 infections and was the predominant subtype in six out of seven administrative territories studied both among people who inject drugs and heterosexually infected persons. As an exception to the dominant role of the Eastern European subtype A strain, the CRF03-AB strain was found to be dominant in the city of Cherepovets located in the north central European Russian territory of Vologda Oblast. The authors conclude that this is the first report of the CRF03-AB strain causing an outbreak outside the Kaliningrad region.

Chang SY, Sheng WH, Lee CN, Sun HY, Kao CL, Chang SF, Liu WC, Yang JY, Wong WW, Hung CC, Chang SC. Molecular epidemiology of HIV type 1 subtypes in Taiwan: outbreak of HIV type 1 CRF07_BC infection in intravenous drug users. AIDS Res Hum Retroviruses 2006;22:1055-66.

In Taiwan, sexual transmission is responsible for most HIV-1 infections with two dominant subtypes, subtype B and CRF01_AE, distributing among homosexual and heterosexual groups, respectively. Recently, injecting drug use has become an emerging route of HIV-1 transmission and contributed to a significant increase of HIV-1 infection. To characterize the HIV isolates responsible for the outbreak among people who inject drugs, Chang and colleagues performed phylogenetic analysis to analyse the protease/RT sequences amplified from HIV-1-infected people who inject drugs at National Taiwan University Hospital and Taipei City STD Control Center. CRF07_BC, which is circulating in northern China, was demonstrated to account for the majority of HIV-1 infection in people who inject drugs in the past 2 years. Although these Taiwanese CRF07_BC sequences shared the same breakpoint positions as those described in the CRF07_BC reference sequences, they formed a unique cluster in the phylogenetic tree, suggesting they originated from a founder virus. This finding was further supported by the relative low genetic diversity and unique sequence features. These results demonstrated the emergence of CRF07_BC and its association with the HIV-1 outbreak among people who inject drugs between 2004 and 2005 in Taiwan. The authors conclude that this finding not only helps us to have a better understanding of the HIV evolution in Asia, but also has important implications for vaccine design in the future.