Faso, HIV-2 and HIV-1 are both present among appreciable proportions of the population.
The geographic pattern of HIV-2 shows a higher prevalence in West Africa and in other African countries with a Portuguese colonial history (Kanki, 1991). Troop movements among these former Portuguese colonies and travel facilitated by cultural ties surely contributed to the spread of HIV-2 in these select countries. Conversely, several countries bordering those with substantial HIV-2 infection have as yet shown little evidence of an HIV-2 epidemic.
The highest prevalence of HIV-2 infection among high-risk urban adults is found in Côte d'Ivoire and The Gambia, where infection rates are 37 percent and 27 percent, respectively. HIV-2 seroprevalence among low-risk urban adults is far lower (see Figure 3-6); only in Guinea-Bissau does seroprevalence exceed 10 percent (U.S. Bureau of the Census, 1994b). The highest HIV-2 infection rates are found among populations with high HIV-1 prevalence, including people with tuberculosis or STDs and female prostitutes. As noted above, in contrast to HIV-1, which shows a distinct peak at ages 25 to 40, the age-specific prevalence of