"Numerous epidemiological studies suggest that people with STDs have a
greatly increased risk for HIV infection," explains Maria Wawer, M.D.,
one of the principal investigators on the study. "We conducted a
controlled trial to see if community-wide treatment of curable STDs
might reduce HIV infection rates." Dr. Wawer, an NIAID grantee at the
Columbia University School of Public Health in New York City, will
present results of the study on July 3, 1998, at the 12th World AIDS
Conference in Geneva, Switzerland.
Dr. Wawer and a team of researchers from Uganda and the United States
began the study, known as the Rakai STD Control for AIDS Prevention
Study, in 1994. The scientists conducted the study in 56 villages in
Uganda's Rakai district, where approximately 16 percent of the
population is infected with HIV. STDs also are highly prevalent in
Rakai. At baseline, for example, approximately 10 percent of the
population had evidence of having had syphilis, while bacterial
vaginosis and trichomoniasis affected about one-half and one-fourth,
respectively, of all women. The prevalence of gonorrhea and chlamydial
infections were about 2 and 4 percent, respectively.
The researchers randomly assigned groups of villages to either the
intervention or comparison arms of the study. In the intervention arm,
6,602 HIV-negative adults between the ages of 15 and 59 received
home-based, observed, antibiotic treatment against a broad range of
STDs, whether or not they had symptoms. A total of 6,124 HIV-negative
adults in the comparison arm were treated in the home for parasitic worm
infections and given nutritional supplements.
Home-based treatments in both the intervention and comparison groups
were repeated every 10 months, at which time all participants were
screened for STDs and tested for HIV infection. Anyone in the
comparison group who had STD symptoms at the time of the in-home study
visits was referred to local project clinics for standard Ugandan STD
treatment. All study participants were instructed to seek treatment at
local clinics, which offered the prevailing standard of care, if they
experienced STD symptoms in-between the visits of the research teams.
After the second 10-month follow-up, an analysis of study data showed
that the treatment for curable STDs had had no effect on HIV incidence,
i.e., the rate of new HIV infections was the same in the intervention
and comparison groups. In fact, HIV infection rates increased slightly
in both groups during the study. On the other hand, the STD treatment
regimen did reduce the prevalence of most targeted STDs. Syphilis and
trichomoniasis were significantly reduced in the intervention group
relative to the comparison group at follow-up. Among pregnant women
enrolled in the study, rates of gonorrhea, chlamydia, trichomoniasis and
bacterial vaginosis were significantly lower in the intervention group
than the comparison group at follow-up. The rate of new HIV infections
among pregnant women, however, was the same in the intervention and
The Rakai findings contrast with the only other completed
community-based study that examined whether STD treatment can reduce the
rate of HIV infection. In 1995, scientists reported results of a study
conducted in the Mwanza region of Tanzania in which entire communities
received either clinic-based treatment of symptomatic STD infections or
the existing standard of care. This region was in a much earlier phase
of the HIV epidemic compared to Rakai - only about 4 percent of the
population was infected with HIV at the time of the study. Although the
Mwanza study showed only limited effects of the intervention on STD
rates, the rate of new HIV infections was 38 percent lower in the
intervention group compared with the control group.
"In Rakai, STDs are associated with increased risk of HIV transmission
in individuals," explains co-principal investigator Ronald Gray, M.D.,
of Johns Hopkins University in Baltimore, Md. "There is also a
substantial background risk of exposure to HIV, irrespective of
concurrent STDs. Thus, STDs may have contributed little to overall HIV
transmission in this population, indicating that differences in the
stage of the HIV epidemic may be important in this regard."
"The Rakai findings underscore the vital need for additional research in
this area," adds Penelope J. Hitchcock, D.V.M., chief of NIAID's
sexually transmitted diseases branch. "Additional trials conducted in
populations in which the epidemic is beginning will help determine the
role of STD control in preventing HIV transmission. Studies to
determine the importance of genital herpes and bacterial vaginosis in
HIV transmission are also needed."
Nelson Sewankambo, MB.ChB., the Ugandan principal investigator of the
current study, from Makerere University, Kampala, stressed the
importance of study findings with respect to the impact on STDs. "The
mass treatment intervention substantially reduced STDs among pregnant
women, and resulted in marked improvement in maternal and infant
health," he noted. "These findings could help define new strategies for
STD control in pregnancy."
Scientists from Makerere University, Kampala; Johns Hopkins University
in Baltimore; and the Uganda Virus Institute of the Uganda Ministry of
Health collaborated with Drs. Wawer, Gray and Sewankambo on the study.
In addition to NIAID, the National Institute of Child Health and Human
Development (NICHD), the Rockefeller Foundation and the World Bank
Uganda STI Project provided support for this study.
NIAID and NICHD are components of the National Institutes of Health
(NIH). NIAID conducts and supports research to prevent, diagnose and
treat illnesses such as HIV disease and other sexually transmitted
diseases, tuberculosis, malaria, asthma and allergies. NIH is an agency
of the U.S. Department of Health and Human Services.
Press releases, fact sheets and other NIAID-related materials are
available on the Internet via the NIAID home page at
http://www.niaid.nih.gov. The home page for the 12th World AIDS
Conference is http://www.aids98.ch.