1. Platyhelminths as Human Parasites
Images from the CDC

2. Trematode Parasites Clonorchis sinensis Fasciola hepatica
Schistosoma spp.
mansoni
japonicum
Haematobium
Paragonimus westermani
Dicrocoelium dendriticum

3. 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

4. Clonorchis sinensis

5. Fasciola hepatica Sheep Liver Fluke
Human infection from eating wild aquatic plants
Symptoms
Hepatosplenomegaly
Anemia
Jaundice
Abdominal Pain
Fatty Food Intolerance

6. Schistosoma spp. Dioecious
Large males with split bodies forming a longitudinal groove
Females housed in groove of male
Adults may live for years

7. Schistosoma spp. Schistosoma mansoni Schistosoma japonicum
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

8. Schistosomiasis

9. 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

10. 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.

11. Schistosomiasis Blood Flukes
200 Million people infected in Africa and Asia
Symptoms
Ascites
Symmer’s Fibrosis
Death via hemorrhage

12. Control of Schistosomes
Proper disposal of body waste
Avoid contact with contaminated water
Vaccine?
Biological Control?
Aswan High Dam
Electricity
Agriculture
Schistosomiasis

13. 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)

14. Dicrocoelium dendriticum
Liver fluke of livestock
Humans are accidental hosts
Mind-controlling effect on ants

15. Cestode Parasites Taenia saginata Taenia solium Diphyllobothrium latum
Echinococcus spp.

16. Taenia saginata Beef Tapeworm Cows are intermediate host
Scolex without hooks
Motile proglottids

17. Taenia solium Pork Tapeworm Pigs are intermediate host
Scolex with hooks

18. Taeniasis

19. Diphyllobothrium latum
Broad Fish Tapeworm
Single worms up to 20 meters
Most severe adult tapeworm disease
Vitamin B12 absorption by worms leads to anemia

20. Diphyllobothriasis

21. Cysticercosis Infection by juvenile tapeworms
Symptoms related to location of cysticerci
Brain
Eyes
Heart

22. Echinococcus spp. Hydatid Disease
Infection by close contact with sheep dogs
Cysts may grow for many years
Surgical removal after scolicidal flush