Overview
Wading into a river to fish, washing clothes at the water’s edge, children swimming and playing in a lake, these are some of the most ordinary activities in many communities, and also exactly how schistosomiasis spreads. The parasite does not need dramatic circumstances to find its way in, just everyday contact with the wrong water.
Disease Summary
- Category
- Infectious Disease
- Cause
- Parasitic flatworms (blood flukes) of the genus Schistosoma
- Transmission
- Skin contact with freshwater containing larvae released by infected freshwater snails
- Body System
- Urinary Tract and Intestines
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Symptoms depend on which form of schistosomiasis is present, and many people, especially with mild infection, have few or no symptoms at first. In some people, particularly those newly exposed, a feverish illness with cough and abdominal pain can develop several weeks after infection.
Blood in the Urine
The classic sign of urogenital schistosomiasis, sometimes visible, sometimes only detectable through a urine test.
Abdominal Pain
Common in intestinal schistosomiasis, often alongside general discomfort.
Diarrhoea or Blood in the Stool
Can occur with intestinal schistosomiasis, particularly with heavier infection.
Skin Rash or Itching
Can appear at the site where larvae entered the skin, sometimes called swimmer’s itch.
Fatigue
General tiredness can accompany the infection, particularly if it has caused anaemia.
Signs of Advanced Disease
These can indicate significant organ involvement and need prompt medical assessment.
Severe Abdominal Swelling
Can indicate fluid buildup from advanced liver involvement and needs prompt assessment.
Persistent Blood in Urine or Stool
Ongoing bleeding should be evaluated, particularly to rule out complications like bladder or organ damage.
Difficulty or Pain When Urinating
Can indicate bladder or urinary tract involvement that needs assessment.
Unusual Vaginal Bleeding or Pelvic Pain
In women, these can be signs of female genital schistosomiasis and deserve prompt evaluation, especially in areas where the disease is common.
Diagnosis
Stool Examination
Detects parasite eggs in the stool, the standard method for diagnosing intestinal schistosomiasis.
Urine Examination
Detects parasite eggs or microscopic blood in the urine, the standard method for diagnosing urogenital schistosomiasis.
Blood Test for Antibodies or Antigens
Useful for people who have travelled to or from endemic areas, or in settings where egg detection is less reliable.
Laboratory Tests
Kato-Katz Stool Examination
A standard microscopy technique that detects and counts Schistosoma eggs in the stool, used mainly for intestinal schistosomiasis.
Urine Filtration and Microscopy
Detects Schistosoma eggs in urine, the standard method for urogenital schistosomiasis.
Urine Reagent Strip Test
Checks for microscopic blood in the urine, a simple field test often used for community screening.
Circulating Cathodic Antigen (CCA) Test
Detects a parasite antigen and is particularly useful for Schistosoma mansoni infection.
Treatment
Praziquantel
An effective, safe, and low-cost medication that treats all forms of schistosomiasis and is used both for individual treatment and large-scale community programmes.
Management of Complications
For advanced disease, additional care may be needed for complications such as bladder or liver damage, separate from treating the underlying infection.
Prevention
Avoid contact with untreated freshwater in endemic areas
Swimming, wading, or washing in lakes, rivers, or irrigation canals in endemic areas carries a risk of infection.
Support mass treatment programmes
Periodic praziquantel treatment of at-risk communities, especially school-aged children, reduces both illness and transmission.
Improve access to safe water and sanitation
Reduces both the need for contact with natural water sources and the contamination of water with parasite eggs.
Support snail control efforts
Reducing the population of the freshwater snails that carry the parasite’s larval stage helps interrupt transmission.
Risk Factors
Higher Risk of Infection
These groups have the most frequent contact with contaminated freshwater.
- School-aged children, who often swim or play in infested water
- Fishermen, farmers, and irrigation workers
- Women doing domestic tasks such as washing clothes in infested water
Increased Risk of Severe Disease
These factors increase the chance of developing more significant illness.
- Heavy or repeated infection over time
- Limited access to treatment or healthcare
Geographic Risk
Where someone lives significantly affects their risk of exposure.
- Living in or travelling to one of the more than 75 countries where schistosomiasis is transmitted, with the highest burden in sub-Saharan Africa
Complications
Bladder and Kidney Damage
Long-term urogenital schistosomiasis can scar the bladder and ureters and, in advanced cases, damage the kidneys.
Liver and Spleen Damage
Chronic intestinal schistosomiasis can enlarge the liver and spleen and lead to fluid buildup in the abdomen.
Infertility
Genital schistosomiasis in both women and men can cause lasting reproductive harm if untreated.
When to Seek Medical Care
Blood in the Urine or Stool
Should be evaluated, particularly in or after time spent in an area where schistosomiasis is common.
Persistent Abdominal Pain or Swelling
Can indicate liver involvement and needs assessment.
Unusual Vaginal Bleeding, Pelvic Pain, or Genital Lesions
May indicate female genital schistosomiasis and deserve prompt evaluation.
Known Freshwater Contact in an Endemic Area
Even without symptoms, anyone with this kind of exposure should ask a healthcare provider about testing.
Prognosis
Excellent With Treatment
A single dose of praziquantel effectively treats the infection and prevents progression to severe disease.
Reinfection Is Common in Endemic Areas
Ongoing contact with contaminated water means periodic retreatment is often needed.
Complications Are Preventable With Early and Repeated Treatment
Even where reinfection occurs, regular treatment substantially reduces the risk of severe, long-term organ damage.
Differential Diagnosis
Urinary Tract Infection
Can also cause blood in the urine and discomfort, though it is caused by bacteria rather than a parasite and responds to antibiotics rather than praziquantel.
Typhoid Fever
Can cause abdominal pain and general illness in the same regions, though it typically also causes a prolonged fever.
Liver Disease from Hepatitis B
Can also cause liver enlargement and abdominal swelling in the same regions, and the two can occur together.
References
World Health Organization (WHO)
World Health Organization fact sheet on schistosomiasis transmission, epidemiology, symptoms, diagnosis, and control strategy.
Centers for Disease Control and Prevention (CDC)
Public information on schistosomiasis causes, symptoms, diagnosis, and treatment.
CDC Clinical Overview of Schistosomiasis
Clinical guidance for healthcare providers on acute and chronic schistosomiasis, testing, and treatment.
Frequently Asked Questions
Is schistosomiasis contagious between people?
No, not directly. It spreads through contact with freshwater containing larvae released by infected snails, not through contact with an infected person.
Can schistosomiasis be cured?
Yes. A single dose of praziquantel effectively treats the infection. Reinfection is common in areas with ongoing water contact, so periodic retreatment is often part of long-term care.
How do I know if water is safe?
In areas where schistosomiasis is common, any untreated freshwater, lakes, rivers, ponds, or irrigation canals, should be considered a possible risk. Water that has been properly treated or comes from a safe piped source does not carry this risk.
Can children get schistosomiasis?
Yes, and school-aged children are among those most affected, since swimming and playing in infested water is common. This is why many treatment programmes specifically target children in endemic areas.