Cryptosporidiosis is a type of opportunistic (AIDS-related) infection seen in HIV-positive patients as their immune systems weaken. It is caused by a parasite that invades the intestinal tract, and it can cause watery diarrhea, stomach cramps, an upset stomach, or a fever. Antibiotics (paromomycin and azithromycin) are usually used to treat cryptosporidiosis. In this study, doctors will look at the effectiveness of using IL-12. IL-12 is a type of protein naturally produced by certain types of cells of the immune system and is believed to be important for immune function. Doctors hope that IL-12 can help boost the immune system in fighting cryptosporidiosis.