Parasitology 11 Schistomiasis

Flukes

• attach to host with ventral and oral sucker

• absorb nutrients through tegument

• blind gut

• professional excreters

• varied reproductive strateg

What are the blood flukes?

Schistosoma hematobium/mansoni/japonicum

Vector for Schisostoma hematobium/mansoni/japonicum

Snails

The main definitive host for Schistosoma spp. (except what species?) is humans.

S. japonicum

What is the intestinal fluke?

Fasciolopsis buski

What is the liver fluke?

Clonorchis sinensis

What is the lung fluke?

Paragonimus westermani

Blood fluke (Schistosoma) life cycle

• eggs hatch and release miracidia

• miracidia penetrate snails

• form sporocysts in snails

• snails release cercariae

• cercariae penetrate skin of human, losing tail

• cercariae become schistosomulae

• circulate and migrate to blood in liver to mature into adults

• paired adult worms lay eggs, exiting in feces or pee

What blood flukes exit in urine?

Schistosoma haematobium

What blood flukes exit in feces?

Schistosoma mansoni and Schistosoma japonicum

1 miracidium releases how many cercarie?

4000

T/F: Snails release cercaria when sun comes up

True

What is this?

Schistosoma cercaria

T/F: Miracidium is only seen in water.

True

What is this?

Schistosoma miracidium

How are male and female Schistosoma worms different in their tegumental surfaces?

Male: Tubercules

Female: Papillae

How does Schistosoma avoid the immune system?

attaching host serum proteins to their tegument

Treatment against Schistosoma?

Praziquantel to disrupt tegument

Where do adult worms of Schistosoma mansoni live in?

inferior mesenteric veins of large intestine

Where do adult worms of Schistosoma japonicum live in?

superior mesentric veins of small intestine

Transporting to what organ leads to egg death and human disease for Schistosoma?

liver

Schistosoma eggs in liver lead to what

pipe stem fibrosis

• chronic exposure promots Th2 cell mediated immune response

• granulomatous response

• periportal liver fibrosis and cirrhosis

• hepta-splenic schistosomiasis

Katayama fever

• what is it?

• caused by what?

• symptoms?

• immunoallergic reaction against schistosoma egg antigens

• S. japonicum and S. mansoni

• shaking chills, hives, shock

What does Schistosoma hematobium target?

urinary bladder

S. hematobium pathology

• bladder fibrosis

• obstructive uropathy

• increased risk of bladder cancer

Schistosoma diagnosis

• eggs in stool or urine

• mucosal scrape or biopsy if negative

• antigens and NAATs are being developed

Which species

Schistosoma mansoni

Which species

Shistosoma japonicum

Which species

Shistosoma hematobium

Treating Katayama Fever

• short course of corticosteroids

• praziquantel INEFFECTIVE against EGGS/LARVAE

Treating post-acute to chronic illness

• target adults with praziquantel

• manage impacts of granulomas

Swimmer’s itch

• caused by Austrobilharzia variglandis

• grow in ducks, then infect humans swimming