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- egg-> miracidium-> parthenita ( sporocyst/redia)-> cercaria -> metacercaria-> adult- w/ snailw/fish/crabw/bird- 19 spp of digeneans use C. californica as 1st IH
--Metacercariae on fish brain, crab caraspace, fish gills - Trophic transmission: Final (definitive) host ingests metacercariae in or on prey items: adult worm develops in digestive tract or associated tissueParasitic castration- Infectious strategy that requires the elimination of host reproduction as the primary means of acquiring energy.Interspecific competition- Putative dominance hierarchy- Solider + Reproductive castes- higher attack rates for F. Echinostomatidae solider than F. Philopthalmidae
Behavioral modification- Parasite Induced Trophic Transmission ( PITT) - The metacercariae of some trematode species are able to cause behavioral modification of the second intermediate (prey) host. These behavioral changes enhance the likelihood of predation by the definitive (predator) host.- Euhaolorchis californiensis metacercariae in fish brain- Makes fish surface, jerk , shimmy, contort, scratch -Ribeiroia ondatrea – cripple ambhibians - Dicrocoelium dendriticum - ants - Leucochloridium paradoxum - sporocysts in tentacles of first intermediate host snail (Succinea sp.)-OrderEchinostomatidae-F. Fasciolidae- Fasciola sp- Liver fluke - Fascioliasis occurs in many areas of the world and usually is caused by F. hepatica, which is a common liver fluke of sheep and cattle.- Fasciola hepatica is found in more than 50 countries, in all continents except Antarctica. Fasciola gigantica is less widespread. Human cases have been reported in the tropics, in parts of Africa and Asia, and also in Hawaii.- Infective Fasciola larvae (metacercariae) are found in contaminated water, either stuck to (encysted on) water plants or floating in the water, often in marshy areas, ponds, or flooded pastures. People (and animals)
typically become infected by eating raw watercress or other contaminated water plants. People also can get infected by ingesting contaminated water, such as by drinking it or by eating vegetables that were washed or irrigated with contaminated water.--Order Plagiochiformes-Paragonimus westermanii – liver fluke infective @ cercariae + meta cercariae - Several species of Paragonimus cause most infections; the most important is P. westermani- Primarily in Asia (China, the Philippines, Japan, Vietnam, South Korea, Taiwan, and Thailand).