March 25, 2003
In a rural population of Guinea-Bissau, HIV-2-positive women had a five times higher prevalence of HTLV-I than HIV-2-negative women, but only one man had both HIV-2 and HTLV-I. In an urban adult population, the association between HIV-2 and HTLV-I occurred in both men and women. Moreover, HTLV-1 infection was four times more likely to occur in HIV-1-positive women than HIV-1-negative women, while no man was dually infected with HIV-1 and HTLV-I.
Studies from Guinea-Bissau have suggested that women over 45 are more likely to become infected with HIV-2 than younger women. The researchers examined other population-based studies to determine whether the same sex and age pattern occurred with HTLV-I and HIV-1 in other parts of Africa, and found that for all three retroviruses, the female:male prevalence rates increased among individuals over ages 45-50.
Increased risk of infection in older women suggests that dual infection should be more common in women than in men, the report states. To further investigate the relative importance of social, behavioral and biological risk factors for the spread of HIV-1, HIV-2 and HTLV-I among older women, the authors reexamined community cohorts of individuals over 35 in the Bissau population.
Investigators interviewed and drew blood samples from 2,057 individuals. They analyzed blood for HIV-1, HIV-2 and HTLV. The interviews covered behavioral and socioeconomic background factors including symptoms of STDs, number of lifetime partners, regular and casual sexual partners within the last 12 months, sex during breastfeeding, circumcisions, menopause, smoking, alcohol consumption, ethnic group, knowledge of/belief in the existence of HIV/AIDS, exchange of sex for money, blood transfusions, traveling patterns, contact with monkey meat, and monkey bites since their last examination. Participants were divided into four age groups: 35-44, 45-54, 55-64, and 65 and older. The researchers performed uni- and multivariate analyses using logistic regression and Poisson regression models.
A total of 1,686 subjects participated with a blood sample in HIV prevalence analyses, and 1,581 participated in HTLV-I prevalence analyses. Overall, the prevalence was 2.1 for HIV-1, 13.5 percent for HIV-2 and 7.1 percent for HTLV-I. Comparing the under-45 age group with 45+ age groups, the authors found the female:male prevalence ratio increased with age for all three retroviruses. Women more commonly had dual infections than men. "Assuming independent distribution of the viruses," Holmgren and colleagues wrote, "the observed prevalence of dual infections in women was significantly higher than expected, while the prevalence was not increased in men." They also found the prevalence of dual infection increased with age in women, and decreased with age in men, a pattern not modified by control for behavioral factors.
"As a natural consequence of the HIV-I epidemic, which so far has affected mainly young adults, older women have not been in the focus of HIV prevention campaigns," the authors concluded. "The current findings of a higher prevalence of retroviral infections than expected in older women imply that they should also be considered as a potentially vulnerable group, and be included in public health programs of HIV/AIDS prevention. In addition, in HIV-2 and HTLV-I prevalent areas, the age distribution of HIV-1 infection may be different due to the interaction with other retroviruses, which means that continuous work on HIV-2 prevention is necessary in all age groups."