Public health efforts in Thailand successfully reduced the sexual transmission of HIV and AIDS, but the transmission of the disease through injection drug use is increasing, according to a study conducted by researchers at the Bloomberg School of Public Health. The study, which appeared in the January issue of Journal of Acquired Immune Deficiency Syndromes, suggests that more HIV prevention efforts are needed to target injection drug users.
“Our study shows that condom use and education can dramatically reduce the transmission of HIV, which is significant for a nation like Thailand with its prominent sex trade industry, but it only addresses part of the problem,” says Kenrad Nelson, the study’s lead author and professor of epidemiology at the Bloomberg School. “HIV transmission through injection drug use remains a serious and growing problem, which appears much harder to prevent.”
In 1991, the government of Thailand instituted the “100 percent condom” campaign, which was designed to encourage safe sexual practices and reduce the transmission of HIV infection from commercial sex workers. To measure the effectiveness of the HIV prevention program, Nelson and his colleagues studied the behavior of 21-year-old men from the Royal Thai Army between 1991 and 1998. Soldiers in the Royal Thai Army are selected for service through a random lottery and, therefore, reflect the general population. All the men were tested for HIV infection and asked questions about their background, sexual habits, medical history, use of condoms and use of injection drugs.
The researchers found that the prevalence of HIV infection among the soldiers dropped from a high of 11.9 percent in 1993 to 2.4 percent in 1998. Visits to sex workers dropped from 80 percent in 1993 to 38 percent by 1998. In addition, fewer men reported having sex with a sex worker before joining the army, falling from 57 percent in 1991 to 8 percent in 1998.
The most dramatic finding was the progressive increased association between a history of injection drug use and HIV prevalence. In 1991, less than 2 percent of the HIV-positive men had a history of injection drug use, but the rate jumped to 25 percent by 1998. The number of men who reported injecting drugs also increased from 1 percent to 4 percent during the same time.
“Governments seem reluctant to confront HIV infection among drug users, who are viewed as a marginalized segment of the population. There is resistance to funding methadone treatment or needle exchange programs in many communities,” Nelson says. “Here in the United States, injection drug use is directly or indirectly responsible for nearly 50 percent of all new HIV infections each year. This research shows that increased public health programs are needed and that strategies to prevent HIV transmission among injection drug users must be included in the effort to prevent the further spread of the global pandemic of AIDS.”
Funding for the study was provided by grants from the Rockefeller Foundation, the HIV Network for Prevention Trials of the National Institutes of Allergy and Infectious Diseases, and the Fogarty International Center of the National Institutes of Health.