Trematodes

Schistosomiasis

• Caused by blood flukes– Most common

• S. haematobium– Africa and Middle East

• S. japonicum– Far east Asia

• S. mansoni– South America, Caribbean and Africa

Schistosomiasis

S. mansoni and S. japonicum

• Can be asymptomatic

• Acute disease– Skin

• Dermatitis at site of cercaria entry

– GI tract• Abdominal pain, diarrhea, ascites

– Hepatosplenomegaly• Enlarged liver and spleen

– Brain• Ectopoic eggs can cause lesions

S. haematobium

• Infects urinary tract– Cystitis, ureteritis, hematuria– Bladder cancer

• Leading cause in affected areas

Schistosoma Eggs

• S. mansoni S. japonicum S. haematobium

Schistosoma mansoni

Schistosoma mansoni

Clonorchiasis

• Clonorchis sinensis– Asia including Korea, China, Taiwan and

Vietnam

• Inflammation and obstruction of biliary ducts– Chronic infections can cause cancer of the

biliary ducts

Clonorchiasis

Clonorchis eggs

Clonorchis sinensis

Clonorchis sinensis

Key for Images• Key• AC=acetabulum (ventral sucker) • IN=intestine • CE=cecum • OS=oral sucker • CL=collar • OV=ovary • CS=cirrus sac • PH=pharynx • EB=excretory bladder • SR=seminal receptacle • EG=eggs (within uterus) • TE=testes • ES=esophagus • UT=uterus • GA=genitoacetabulum • VT=vitellaria

Fascioliasis

• Fasciola hepatica (sheep liver fluke)– Worldwide

• Fasciola gigantica– Asia, Africa, Hawaii

• Inflammation and obstruction of biliary ducts– Abdominal pain, fever vomiting and diarrhea– Hepatomegaly (enlarged liver)

Fascioliasis

Fasciola hepatica Egg

Fasciola hepatica

Fasciola hepatica

Key for Images• Key• AC=acetabulum (ventral sucker) • IN=intestine • CE=cecum • OS=oral sucker • CL=collar • OV=ovary • CS=cirrus sac • PH=pharynx • EB=excretory bladder • SR=seminal receptacle • EG=eggs (within uterus) • TE=testes • ES=esophagus • UT=uterus • GA=genitoacetabulum • VT=vitellaria

Fasciolopsiasis

• Fasciolopsis buski

• Light infections are asymptomatic

• Heavy infections– Diarrhea, abdominal pain, fever and ascites– Intestinal obstruction can occur

• Eggs indistinguishable from Fasciola hepatica

Fasciolopsis and Fasciola Eggs

Fasciolopsis Fasciola

Fasciolopsis buski

Fasciolopsiasis

• Dicrocoelium dendricitum

• Most common in grazing ruminants– Rare in humans, carnivores and other

herbivores

• Worldwide distribution

• Metacercariae in ants cause change in behavior

Dicrocoeliasis

Dichrocoeliasis