[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Trematodes (flukes)](https://durgical.com/en/microbiology/groups/trematodes/) › Schistosoma mansoni / S. haematobium / S. japonicum

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# Schistosoma mansoni / S. haematobium / S. japonicum

- Parasite
- Exam priority: medium

A worm that enters through the skin when bathing in fresh water with infected snails. Its eggs damage the liver, bowel or bladder.

Updated 2026-11-01

Also called: bilharzia, blood fluke

## Key points

- Infection through the skin in fresh water.
- Lateral spine (mansoni), terminal (haematobium), small (japonicum).
- S. mansoni → presinusoidal portal hypertension.
- S. haematobium → haematuria and squamous cell bladder cancer.
- Praziquantel.

## At a glance

**Shape**
The male holds the female in its gynaecophoral canal; pairs live in veins

**Family**
Schistosomatidae

**Type**
Blood trematode with separate sexes

**Size**
Adults 1–2 cm

## Morphology

- S. mansoni: large egg with a prominent lateral spine.
- S. haematobium: large egg with a terminal spine.
- S. japonicum: rounder egg with a small, inconspicuous spine.

## Transmission

- Skin contact with fresh water containing cercariae: bathing, fishing, washing clothes, irrigation.
- Not transmitted by salt water or person to person.

**Reservoir:** Humans (S. mansoni, S. haematobium); Domestic and wild animals for S. japonicum; Freshwater snails (Biomphalaria, Bulinus, Oncomelania) as intermediate hosts

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Life cycle

- Eggs leave in stool (S. mansoni, S. japonicum) or urine (S. haematobium) and hatch in fresh water.
- The miracidium infects a specific snail and multiplies through two generations of sporocysts.
- The snail releases cercariae that penetrate the skin of people in the water.
- They drop their tails (schistosomula) and travel in the blood to the lung and liver, where they mature.
- Pairs migrate to the mesenteric veins (mansoni, japonicum) or the vesical plexus (haematobium).
- They lay eggs: some exit into the bowel or bladder; others are trapped in tissue and form granulomas.

## Virulence factors

- Trapped eggs, not adults, cause the disease: granulomas and fibrosis.
- Periportal fibrosis → presinusoidal portal hypertension with preserved liver function.
- Bladder: haematuria, fibrosis, obstructive uropathy and squamous cell carcinoma.
- Female genital schistosomiasis, which raises HIV risk.

## Diseases it causes

- Intestinal, hepatosplenic or urogenital schistosomiasis [Schistosomiasis →](https://durgical.com/en/conditions/schistosomiasis/)
- Presinusoidal portal hypertension with varices from periportal fibrosis (S. mansoni, S. japonicum) [Portal hypertension →](https://durgical.com/en/conditions/portal-hypertension/)
- Squamous cell carcinoma of the bladder (S. haematobium) [Bladder cancer →](https://durgical.com/en/conditions/bladder-cancer/)

## Clinical picture

- Cercarial dermatitis hours or days after bathing.
- Acute schistosomiasis: fever, cough, urticaria and eosinophilia weeks later.
- Hepatosplenomegaly and bleeding oesophageal varices.
- Terminal haematuria in the urogenital form.

## Diagnosis

- Eggs in stool (Kato-Katz) or urine (filtration of a midday sample); samples are repeated.
- Rectal or bladder biopsy when samples are negative.
- Serology for travellers without detectable eggs.
- Ultrasound: periportal fibrosis.

## Treatment

Praziquantel is the drug of choice for all species.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Praziquantel](https://durgical.com/en/pharmacology/praziquantel/)

## Prevention

- Avoid freshwater contact in endemic areas.
- Sanitation so that faeces and urine do not reach the water.
- Snail control.
- Periodic mass praziquantel administration in endemic communities.

## In Colombia

There is no transmission in Colombia. In South America S. mansoni persists in Brazil, Venezuela and Suriname, so in Colombia it is seen in travellers and migrants from those areas or from Africa.

## Memory aid

Mansoni spine on the side, haematobium spine at the tip: the side spine heads for the liver, the tip spine for the bladder.

## Test yourself

Think of the answer, then tap the question to see it.

## How does Schistosoma enter the human body?

Cercariae released by snails penetrate the skin during contact with fresh water.

## Which Schistosoma species is linked to bladder cancer?

S. haematobium, linked to squamous cell carcinoma of the bladder.

## What type of portal hypertension does S. mansoni cause?

Presinusoidal, from periportal fibrosis, usually with preserved liver function.

## Which egg feature identifies S. mansoni?

A prominent lateral spine.

## Is there locally acquired schistosomiasis in Colombia?

No; in South America S. mansoni is transmitted in Brazil, Venezuela and Suriname.

[Add to my cards (5)](https://durgical.app/estudiar/?add=/en/microbiology/schistosoma-mansoni-s-haematobium-s-japonicum/)

## Related

- [Fasciola hepatica](https://durgical.com/en/microbiology/fasciola-hepatica/)
- [Paragonimus spp.](https://durgical.com/en/microbiology/paragonimus-spp/)
- [Clonorchis sinensis / Opisthorchis spp.](https://durgical.com/en/microbiology/clonorchis-sinensis-opisthorchis-spp/)

## Related conditions

- [Schistosomiasis](https://durgical.com/en/conditions/schistosomiasis/)
- [Portal hypertension](https://durgical.com/en/conditions/portal-hypertension/)
- [Bladder cancer](https://durgical.com/en/conditions/bladder-cancer/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Trematodes (flukes)](https://durgical.com/en/microbiology/groups/trematodes/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [CDC - DPDx - Schistosomiasis Infection](https://www.cdc.gov/dpdx/schistosomiasis/index.html) (CDC, 2024); [Schistosomiasis](https://www.who.int/news-room/fact-sheets/detail/schistosomiasis) (WHO, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/schistosoma-mansoni-s-haematobium-s-japonicum/