August 19, 2003
The authors believe that simple country-by-country analysis can help prevent the worldwide spread of AIDS. "Almost all new HIV infection occurs when an infected person shares body fluids with an uninfected person, so prevention programs must focus on situations in which this is happening," the researchers wrote. "This should be obvious, but ... many countries do not even collect the information they need to determine which behaviors are responsible for most new HIV infections. We believe that relatively simple analyses can highlight the differences in categories of exposure between prevalent and incident cases of HIV, can point to important shifts in patterns of transmission, and can in turn lead to better prevention programming."
The researchers examined current levels and trends in prevalence patterns in Cambodia, Indonesia, Honduras, Russia, and Kenya. Even countries considered to have the same type of epidemic -- i.e., low-level, concentrated, or generalized -- showed wide variation of incidence by category of exposure. "Failure to examine current patterns of incidence can lead to inappropriate prevention efforts," they wrote.
Although drug injection and sex work accounted for approximately the same proportion of infections in Indonesia in 2002, according to the study, an escalating epidemic of injection drug use is likely to account for more than 75 percent of new HIV infections in 2003.
Cambodia is classified as having a generalized epidemic, meaning that the nexus of infection has shifted beyond identifiable high-risk groups. But most people becoming infected have partners who exhibited high-risk behavior in the past. The scientists suggested that if Cambodia continues its success in reducing risky sex-work transactions and succeeds in reducing transmission between spouses, HIV prevalence could fall to the low endemic levels of many industrialized nations.
Kenya is also classified as having a generalized epidemic. By 1989, national HIV prevalence in adults reached nearly 4 percent. HIV prevalence among Nairobi sex workers then was 60-70 percent. Despite prevention efforts and an increase in condom use with non-marital partners, sex work remains a key factor in the spread of HIV.
Although recent emphasis has been on altering structural factors such as poverty and sexual inequality that prevent people from protecting themselves from HIV, the study stated, "an understanding of the dynamics of a country's HIV epidemic, how it changes over time, and who is currently at greatest risk is essential to guiding decisions about effective prevention." The authors pointed out that structural change takes time. They urged public health officials to focus on new infections and let political and religious leaders take the lead on initiating changes in the social and cultural factors that influence sexual and drug-taking habits.
British Medical Journal
06.21.03; Vol. 326; No. 7403: P.1384-1387; Elizabeth Pisani; Geoff P. Garnett; Nicholas C. Grassly; Tim Brown; John Stover; Catherine Hankins; Neff Walker; Peter D. Ghys