Isospora is a genus of protozoan parasites belonging to the phylum Apicomplexa. These organisms primarily infect the intestines of various animals, including humans, causing a disease known as isosporiasis. The life cycle of Isospora involves both sexual and asexual reproduction, typically occurring in the intestines of the host. In humans, Isospora belli is the most notable species, often affecting individuals with weakened immune systems, such as those with HIV/AIDS. Symptoms of isosporiasis can include diarrhea, abdominal pain, and weight loss. Treatment usually involves specific antibiotics to eliminate the infection.