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Trematode Parasites
• Clonorchis sinensis• Fasciola hepatica• Schistosoma spp.
– mansoni– japonicum– Haematobium
• Paragonimus westermani• Dicrocoelium dendriticum
Clonorchis sinensis• Chinese Liver Fluke• 20 Million Infected
People• Infection by eating raw
or udercooked fish (pickled fish)
• Flukes live in bile ducts• Symptoms
– Pain in upper rt. Quadrant
– Hepatosplenomegaly– Gall Stones– Obstructive Jaundice– Bile Duct Cancer
Fasciola hepatica• Sheep Liver Fluke• Human infection
from eating wild aquatic plants
• Symptoms– Hepatosplenomegaly– Anemia– Jaundice– Abdominal Pain– Fatty Food
Intolerance
Schistosoma spp.
• Dioecious• Large males with
split bodies forming a longitudinal groove
• Females housed in groove of male
• Adults may live for 10-30 years
Schistosoma spp.• Schistosoma mansoni
– Egg with large subterminal spine
– Adults in veins of large intestine
• Schistosoma japonicum– Egg with diminutive
subterminal spine– Adults in veins of small
intestine
• Schistosoma haematobium– Egg with terminal spine– Adults in veins of urinary
bladder
Intermediate Hosts of Schistosomes
• Schistosoma mansoni– Africa, S. America, West
Indies– Int. Host - Biomphalaria
• Schistosoma japonicum– Asia– Int. Host - Oncomelania
• Schistosoma haematobium– Africa– Int. Host - Bulinus
Schistosome Cercaria
• Cercariae penetrate skin of definitive host
• Schistosomes that normally parasitize birds may produce the rash known as swimmer’s itch. The rash is the result of an immune response to the cercariae.
Schistosomiasis
• Blood Flukes• 200 Million people
infected in Africa and Asia
• Symptoms– Ascites– Symmer’s Fibrosis– Death via
hemorrhage
Control of Schistosomes
• Proper disposal of body waste
• Avoid contact with contaminated water
• Vaccine?• Biological Control?• Aswan High Dam
– Electricity– Agriculture– Schistosomiasis
Paragonimus westermani• Lung Fluke• Widely Distributed
– >10 million people infected in China
• Infection by eating raw or undercooked crustaceans
• Symptoms– Chronic Cough– Purulent, blood-streaked
sputum– Jacksonian Epilepsy,
meningitis (cerebral infection)
– Death (pericardial infection)
Dicrocoelium dendriticum
• Liver fluke of livestock
• Humans are accidental hosts
• Mind-controlling effect on ants
Taenia saginata
• Beef Tapeworm• Cows are
intermediate host• Scolex without
hooks• Motile proglottids
Diphyllobothrium latum
• Broad Fish Tapeworm
• Single worms up to 20 meters
• Most severe adult tapeworm disease– Vitamin B12
absorption by worms leads to anemia
Cysticercosis
• Infection by juvenile tapeworms
• Symptoms related to location of cysticerci– Brain– Eyes– Heart
Echinococcus spp.
• Hydatid Disease• Infection by close
contact with sheep dogs
• Cysts may grow for many years
• Surgical removal after scolicidal flush