endoparasites

Endoparasites are parasites that live inside the bodies of their hosts. They can be unicellular organisms, such as protozoa, or multicellular worms, known as helminths. Endoparasites are contrasted with ectoparasites, which inhabit the surface of the host or its external tissues. Many endoparasites have life cycles that involve one or more hosts or vectors and can be transmitted by contaminated food or water, direct skin penetration, or insect bites.

Protozoan endoparasites include Giardia lamblia, Entamoeba histolytica, Cryptosporidium spp., Plasmodium spp. (malaria), and Toxoplasma gondii. Helminth endoparasites include nematodes such as Ascaris lumbricoides, Trichuris trichiura, hookworms (Ancylostoma/Necator), Enterobius vermicularis; cestodes such as Taenia solium and Taenia saginata; and trematodes such as Schistosoma spp. and Fasciola hepatica. The clinical impact ranges from mild, intermittent symptoms to severe disease, depending on species, parasite burden, and host factors. Common manifestations include diarrhea, abdominal pain, anemia, malnutrition, biliary or hepatic disease, and tissue injury from larval migration.

Diagnosis relies on parasite detection in stools, urine, blood, or tissues, using microscopy, antigen tests, serology, molecular assays, or imaging when organs are involved.

Treatment is species specific and may include albendazole or mebendazole for many nematodes, praziquantel for cestodes and trematodes, metronidazole or nitazoxanide for some protozoa, and antimalarial drugs for Plasmodium infections. Prevention focuses on sanitation, safe drinking water, food handling, vector control, proper cooking of meat, and health education.