Over 25 million HIV-1 infected individuals are currently living in Africa and as many as 50-90% may be co-infected with soil transmitted helminths such as roundworms, hookworms or whipworms. Helminth infection in HIV-1-infected individuals may increase HIV-1 RNA levels and increase the rate of progression of HIV-1 to AIDS. Studies have also shown that successful treatment of helminth co-infection (as documented by clearance of helminth eggs in stool) led to a significant decrease in HIV-1 plasma viral load (-0.36 log10). This change in viral load was significantly greater than that seen in those individuals without documented clearance of their helminth co-infection (+0.67 log10) (p=0.04). Studies conducted in Africa have shown an estimated 2.5-fold increased risk for sexual transmission of the HIV-1 for each log increase in plasma HIV-1 viral load. In addition to direct effects on plasma viral load, the rate of CD4 cell decline in helminth infected individuals may be directly impacted by the significant immune activation seen with such co-infection.