Many HIV infected individuals live in crowded urban settings. These conditions are associated with repeated intestinal parasite infections (helminths), which may alter the immune system in individuals with HIV and AIDS. This alteration in the immune system may increase both the susceptibility to other infections and the severity of these infections in these individuals. Prior studies have shown that in HIV infected individuals, intestinal parasites are associated with increased levels of the HIV virus circulating in the blood. Studies have also clearly shown that in individuals with HIV, progression to AIDS can be predicted by the quantity of HIV virus detectable within the blood. It is important to determine whether treating helminth co-infection in patients with HIV will help individuals control HIV infection and slow disease progression.