ANT 374 Thursday November 3!!EXAM on Tuesday!!Readings through 28 may be covered on the exam. No out of class essay, shorter in class essay.!!Parasites: Trematodes (Flatworms)!Flatworms are flat to help avoid O2/oxygen depletion!" -no circulatory system!" -all cells near the surface of the worms!" -digestive system!" -reproduce sexually!Schistosomiasis (Bilharzia) -venous parasite!-three important species!" 1) S. haematobium!" 2) S. japonicum!" 3) S. mansoni!" Commonalities between these three species:!" -aquatic snail is the intermediate host (each species has a different kind of snail host)!" -eggs cause disease!" " -lodged in tissues!" " -immune response causes disease in response to the eggs!" " " -inflammation!" " " -intestinal and bladder bleeding!" " " -blockage of some veins which causes backup of blood in other areas!""Each adapted to different human venous system!""S. haematobium: bladder veins!" " " -bloody urine!" " " -"male menstruation"!" " " " -most body at 12-15 years!" " " -Africa & Middle East!""S. japonicum: upper intestine veins!" " " -most virulent!" " " -first identified and described in Japan!" " " -China, Philippines, SE Asia!""S. mansoni: lower intestine veins!" " " -originally Africa & Middle East!" " " -brought to South America by slaves!" Symptoms:!" " -"swimmers itch" cause by burrowing of the parasite !" " -aches, fever, cough!""-intestinal types: blocked intestines, obstructed liver!""-urinary type: excessive bleeding → anemia !" Schistosoma Life Cycle!" Schistome eggs enter water from urine or feces (must be freshwater)!" -larvae hatch - seek snail host!" " -propelled by cilia!" " -survives for 24 hours in water unless they find a snail host!" -larvae drill into snail with enzymes:!" " -transform into sporocyst!" " " -asexual reproduction!" " " -infective stage!" " " " -fork-tailed cercaria (stage which is infective to humans)!" -cercaria leave the snail by the 1000's per day:!" " -cercaria survive 2-3 days!" -hosts - usually poor rural!" " -fisherman, rice farmers!" " -clothes washing!" " -bathing, playing!" -cercaria bores into skin: bloodstream → liver!" -matures in liver!" -travels to appropriate veins in which they mate and produce eggs!" Boy meets girl:!" " -male has groove for female!" " -monogamous!" " -may remain in embrace 30 years!" " -3500 eggs/day!" Schistosomiasis Effects:!" Most disease comes from the eggs:!" " -eggs drill through the veins to enter bladder/intestines!" " " -many get stuck!" " " -body surrounds eggs with fibrous tissue!" " " -vessels could become partially/fully blocked in the lungs, spleen, or heart!" Disease more debilitating than it is deadly!" " -200 million worldwide!" " " -85% in Africa!" " " -2nd to malaria in prevalence!""-can be fatal!" " -loss of productivity is the most important factor******* " " -impact on history in the 20th century: vvvvv Schistosomiasis helped Taiwan stay independent from mainland China:!" " -1948: Chaing Kai-shek fled from China to Taiwan!" " -China wished troops from North to South to train for assault!" " -Troops paralyzed by fever and diarrhea within weeks!""Before new plan could be drawn up: Taiwan protected by US navy!" " Communist government instituted eradication program: "People's War against the Snail"! !Helminths- intestinal worms!!"unholy trinity" steals nutrition from their hosts!!hookworm most dangerous for pregnant women- can cause low birth weights, anemia, and punctures intestines which causes
View Full Document