Parasitology Week 8 Notes: Class Cestoda and Trematoda
Parasitology Week 8 Notes: Class Cestoda and Trematoda 35645
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This 2 page Class Notes was uploaded by Progress Asoluka on Friday October 14, 2016. The Class Notes belongs to 35645 at University of Colorado Denver taught by Dr. Jones in Fall 2016. Since its upload, it has received 2 views. For similar materials see Advanced Topics- Parasitology in Biology at University of Colorado Denver.
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Date Created: 10/14/16
Parasitology week 8 Class Cestoda: Parasitic tapeworms; sexually mature cestodes generally live in intestines of all vertebrates classes( can live in coelom but rarely), 2 genera are known to parasitize invertebrates 1. Bodies a. Composed of scolex( anterior end, contains hooks and suckers of various types, also have grooves that help tapeworm called bothria attach to body of host), neck, and series of proglottids. Neck contain stem cells b. There are thousands of proglottids i. Tapesworms in humans about 50 feet, about 100 feet in mammals 2. Sexual reproduction a. These are hermaphrodites, but self fertilization is rare i. Larvae contains infective protoscoleces(juvenile scolices) 1. Cryticercus larva: fluid filled bladder 2. Hexacanth: cestode hatchlings have 6 hooks present 3. Life cycle a. Adults in definitive host-->eggs-->eggs eliminated→ intermediate host (cattle)--> larvae ingested by definitive host 4. Causes a. PITT (parasitic induced trophic transmission) i. Causes changes in behavior, anatomy, or physiology in a host to enhance its dispersal to another host. ii. Cestodiases: tapeworm infections 1. Light parasite loads lead to asymptomatic symptoms 2. Heavy parasitic load leads to a. Decreased rate of growth, survival, and reproduction i. Decreased fat reserves b. Anemia ( decreased hematocrit) c. Deformities during development d. Inflammation of epithelia in digestive tracts-->nausea and diarrhea e. Large numbers can obstruct digestive system(but not as often as round worms) 5. In humans a. Most dangerous is Taenia solium i. Larvae enters tissues and causes an infection called cystercercosis 1. Can infect various area of the body including the brain a. Causing epilepsy, swelling and atrophy of muscles, visual problems Class Trematoda (“trematodes”): includes subclass Digenea (“digeneans”). All are endoparasites, and the largest groups are a members of subclass digeneans. 1. Life cycle a. Complex and variable life cycles (most species seem to have 3 obligate host) b. 1st hosts are almost always molluscs- suggesting that trematodes appeared in this group. c. Include alternating asexual reproduction ( in molluscs) and sexual reporductin( in vertebrates) i. Cartilaginous fishes ( sharks etc) ii. Cosmopolitan distribution representing significant parasites 2. Structure a. Flat or cylindrical bodies b. Oral sucker on anterior end: often a ventral sucker too c. Hermaphrodites that usually don’t self-fertilize