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Unformatted text preview: 5. Life cycle - complex (see text) III. Aschelminthes- Round worms A. Rounded body shape B. Dioecious - separate sexes C. Possess digestive system with mouth and anus. D. Life cycles - some include intermediate hosts, immature stages E. Enterobius vermicularis- Pin worms 1. Infection due to ingestion of eggs 2. In intestine eggs hatch mature adults 3. At night adult female lays eggs on skin in perianal region (See fig. in text) F. Necator americanus- Hook worms 1. Mouth parts hook-like - attach to intestinal wall 2. Feeds on blood of host 3. Eggs passed in stool 4. Larvae in soil penetrate skin of host 5. Blood lungs small intestine (see life cycle in text) G. Trichinella spiralis 1. Larvae encyst in muscle of infected pig. 2. Infection due to consumption of poorly-cooked pork. 3. Larvae becomes encysted in host muscles 2...
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- Spring '09