![](/olcweb/styles/shared/spacer.gif) | ![](/sites/dl/free/0072320427/title/cover_image.JPG) Foundations in Microbiology, 4/e Kathleen Park Talaro,
Pasadena City College Arthur Talaro
The Parasitic Diseases of Humans
Chapter Overview- Parasitology is the study of infections and diseases caused by protozoans and helminth worms.
- Protozoa are small, usually single-celled amebas, ciliates, flagellates, or apicomplexans that may have complex life cycles with several morphological forms.
- Protozoan diseases are spread by food, by contact with other humans and animals, or by arthropod vectors.
- Protozoan diseases can be managed by drugs, proper hygiene, and vector control.
- Diseases caused by infectious amebas include amebic dysentery, and encephalitis. Ciliates are responsible for balantidiosis.
- Flagellate diseases include trichomoniasis, giardiasis, trypanosomiasis, and leishmaniasis.
- The major apicomplexan diseases are malaria, toxoplasmosis, and cryptosporidiosis.
- Helminth parasites are multicellular worms with specialized adaptations in structure and life cycle for feeding, reproduction, and host transmission.
- Diseases are spread by eggs and larvae that are eaten or burrow into the skin. Some involve transmission by vector hosts.
- Helminth worms include nematodes (roundworms), trematodes (flukes), and cestodes (tapeworms).
- Intestinal nematode diseases include ascariasis, hookworm, strongyloidiasis, and trichinosis.
- Tissue nematode infections are vector-borne filariasis and onchocerciasis.
- Flukes are agents of schistosomiasis and zoonotic liver diseases.
- Human tapeworms are acquired from eating poorly cooked beef and pork.
- Control of helminth infections is achieved by administering drugs that paralyze or kill the worms and by interrupting their life cycles.
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