The investigators propose a study to characterize the short-term effect of antihelminth therapy on HIV disease progression, markers of immune activation and levels of HIV in genital secretions. They also plan to determine the prevalence of helminth infection in individuals with HIV. This study will examine factors that might affect an individual's risk of helminth infection, such as CD4 count, viral load, age, gender and duration of time spent in an urban setting. In addition, the investigators will conduct a randomized clinical trial to determine the effect of treating helminth infection on markers of immune activation, HIV disease progression and risk of transmission as measured by HIV-1 RNA in genital secretions. The study will be conducted in a group of HIV infected individuals in and around Nairobi, Kenya who do not yet meet criteria for highly active antiretroviral therapy (HAART).