Skip to content
Inciteful Med

Understanding Schistosomiasis (Bilharzia)

Last updated:

Schistosomiasis (bilharzia) is a highly treatable parasitic infection caught from contaminated freshwater, not from other people. It is effectively cured using a medication called praziquantel, which stops the infection and prevents long-term damage to the liver, intestines, or bladder.

Key Takeaways

  • • Schistosomiasis is caused by parasitic flatworms that penetrate the skin during contact with contaminated freshwater.
  • • The infection is not contagious and cannot be spread from person to person.
  • • Praziquantel is the gold-standard, highly effective treatment used to cure the infection.
  • • Many people infected with schistosomiasis have no symptoms, making testing important after high-risk travel exposure.
  • • Untreated chronic schistosomiasis can cause long-term inflammation in the liver, intestines, or bladder.

Finding out you have a parasitic infection can feel overwhelming, but schistosomiasis (also known as bilharzia) is a well-understood and highly treatable condition [1][2]. It is not a reflection of your hygiene, and it is not a “permanent” illness. By understanding how it works, you can take control of your recovery.

What is Schistosomiasis?

Schistosomiasis is an infection caused by parasitic flatworms (schistosomes) [3]. These tiny worms live in certain types of freshwater snails found in subtropical and tropical regions [4][3].

The infection happens in a specific way:

  • Water Contact: The snails release microscopic larvae into freshwater (lakes, rivers, or streams) [4][5].
  • Skin Penetration: When a person swims, bathes, or wades in this water, the larvae attach to and penetrate the skin [4][6].
  • Internal Growth: Once inside, the larvae travel through the body and mature into adult worms, which live in the blood vessels near the intestines or bladder [7].

Four Stabilizing Facts

If you are feeling anxious about a diagnosis or potential exposure, keep these facts in mind:

  1. It is highly treatable: A medication called praziquantel (PZQ) is the gold-standard treatment [1]. It is effective against all common species of the parasite and usually works quickly to stop the infection [2][8].
  2. It is NOT contagious: You cannot “catch” schistosomiasis from another person [1]. It is not spread through coughing, sneezing, hugging, or sexual contact [9]. You only get it from direct contact with contaminated freshwater [6].
  3. Modern medicine is very familiar with it: While it may seem “exotic” in some countries, it is one of the most common parasitic infections globally [10]. Doctors, especially travel medicine specialists, have clear protocols for diagnosing and curing it [11][12].
  4. Household transmission is impossible: Even though the parasite’s eggs exit your body through urine or stool, shedding eggs into a modern toilet poses zero risk to your family members. The eggs require a specific freshwater snail to hatch and grow [4].

Common Misunderstandings

There are many myths about how people get bilharzia. Clearing these up can help you understand your risks and how to stay safe in the future.

Myth Fact
“I got it from drinking the water.” You generally do not get schistosomiasis by drinking water. The larvae must penetrate your skin [4][6]. However, the larvae can penetrate the lining of your mouth or throat if you drink contaminated water [10].
“I’m safe if I stay in deep water.” The snails and larvae can be found in various parts of the water, and fetching water from “deeper” areas does not guarantee safety [13].
“Only local residents get it.” Travelers are frequently diagnosed with schistosomiasis after recreational activities like rafting or swimming in endemic rivers [14][11].
“I would know if I was sick.” Over half of travelers with the infection have no symptoms at all (asymptomatic) [11]. This is why testing is important after high-risk exposure.

The Two Phases of Infection

Doctors often talk about “acute” vs. “chronic” phases. Knowing which one you might be in helps guide your care.

  • Acute Phase (Katayama Fever): This is a sudden immune reaction to the young worms [12]. It is more common in travelers and can cause fever, chills, cough, and muscle aches weeks after exposure [12][11].
  • Chronic Phase: This happens if the infection goes untreated for a long time [3]. The adult worms lay eggs, and it is the body’s reaction to these eggs—not the worms themselves—that causes long-term inflammation in the liver, intestines, or bladder [3][6].

It is important to know that many patients skip the acute phase entirely and enter an asymptomatic chronic phase. A lack of “Katayama fever” does not mean you are infection-free [11].

The good news is that treatment with praziquantel targets the worms in both phases, preventing further damage [1][2].

Frequently Asked Questions

How do you get schistosomiasis?
You get schistosomiasis when your skin comes into contact with contaminated freshwater in tropical or subtropical regions. Microscopic parasite larvae released by certain snails penetrate your skin while you are swimming, wading, or bathing.
Is bilharzia contagious from person to person?
No, schistosomiasis is not contagious. You cannot catch it from another person through coughing, hugging, sexual contact, or sharing a bathroom. The parasite requires a specific freshwater snail to complete its life cycle.
How is schistosomiasis treated?
Schistosomiasis is highly treatable with a prescription medication called praziquantel. This drug is the gold standard for curing the infection and works effectively against all common species of the parasite.
What are the symptoms of schistosomiasis?
Many people have no symptoms at all, which is why testing is important after exposure. When symptoms do occur, the acute phase can cause fever, chills, cough, and muscle aches. In the chronic phase, the infection can cause inflammation in the liver, intestines, or bladder.
Can I get schistosomiasis from drinking water?
While the primary way people get infected is through skin penetration during swimming or wading, the parasite larvae can also penetrate the lining of your mouth or throat if you drink contaminated freshwater.

Questions for Your Doctor

  • • Based on my travel history, which species of Schistosoma am I most likely to have?
  • • Is my infection in the 'acute' phase (Katayama fever) or the 'chronic' phase, and how does that change my treatment plan?
  • • What is the specific dose of praziquantel I need, and should I take it with food?
  • • When should we perform a follow-up test to confirm the treatment was successful?
  • • Are there any long-term effects on my liver or bladder that we should monitor?

Questions for You

  • • When and where was my most recent contact with freshwater (lakes, rivers, or streams)?
  • • Did I experience a 'swimmer's itch' rash or a sudden fever shortly after being in the water?
  • • What are my main concerns or fears about this diagnosis that I want to discuss with my care team?

Want personalized information?

Type your question below to get evidence-based answers tailored to your situation.

References

  1. 1

    Schistosomiasis.

    McManus DP, Dunne DW, Sacko M, et al.

    Nature reviews. Disease primers 2018; (4(1)):13 doi:10.1038/s41572-018-0013-8.

    PMID: 30093684
  2. 2

    Single-cell RNA sequencing reveals a peripheral landscape of immune cells in Schistosomiasis japonica.

    Li J, Zhang Y, Li H, et al.

    Parasites & vectors 2023; (16(1)):356 doi:10.1186/s13071-023-05975-y.

    PMID: 37817226
  3. 3

    Schistosomiasis-from immunopathology to vaccines.

    McManus DP, Bergquist R, Cai P, et al.

    Seminars in immunopathology 2020; (42(3)):355-371 doi:10.1007/s00281-020-00789-x.

    PMID: 32076812
  4. 4

    Status Quo and Future Perspectives of Molecular and Genomic Studies on the Genus Biomphalaria-The Intermediate Snail Host of Schistosoma mansoni.

    Au MFF, Williams GA, Hui JHL

    International journal of molecular sciences 2023; (24(5)) doi:10.3390/ijms24054895.

    PMID: 36902324
  5. 5

    Genome of the ramshorn snail Biomphalaria straminea-an obligate intermediate host of schistosomiasis.

    Nong W, Yu Y, Aase-Remedios ME, et al.

    GigaScience 2022; (11()) doi:10.1093/gigascience/giac012.

    PMID: 35166339
  6. 6

    Human schistosomiasis.

    Buonfrate D, Ferrari TCA, Adegnika AA, et al.

    Lancet (London, England) 2025; (405(10479)):658-670 doi:10.1016/S0140-6736(24)02814-9.

    PMID: 39986748
  7. 7

    Prevalence of Schistosoma Haematobium Measured by a Mobile Health System in an Unexplored Endemic Region in the Subprefecture of Torrock, Chad.

    Lalaye D, de Bruijn ME, de Jong TP

    JMIR public health and surveillance 2019; (5(2)):e13359 doi:10.2196/13359.

    PMID: 31215519
  8. 8

    Unexpected rapid symptom response after praziquantel to intestinal Schistosoma mansoni symptoms: A case report from Rwanda.

    Sibomana JP, Getaneh FB, Graham B, Giraneza R

    SAGE open medical case reports 2023; (11()):2050313X231190013 doi:10.1177/2050313X231190013.

    PMID: 37533487
  9. 9

    Have You Heard of Schistosomiasis? Knowledge, Attitudes and Practices in Nampula Province, Mozambique.

    Rassi C, Kajungu D, Martin S, et al.

    PLoS neglected tropical diseases 2016; (10(3)):e0004504 doi:10.1371/journal.pntd.0004504.

    PMID: 26942416
  10. 10

    COMMUNITY PERCEPTIONS OF SCHISTOSOMIASIS TRANSMISSION, PREVALENCE AND CONTROL IN RELATION TO AQUATIC HABITATS IN THE LAKE VICTORIA BASIN OF KENYA.

    Adoka SO, Anyona DN, Abuom PO, et al.

    East African medical journal 2014; (91(7)):232-44.

    PMID: 26862658
  11. 11

    Schistosomiasis in European Travelers and Migrants: Analysis of 14 Years TropNet Surveillance Data.

    Lingscheid T, Kurth F, Clerinx J, et al.

    The American journal of tropical medicine and hygiene 2017; (97(2)):567-574 doi:10.4269/ajtmh.17-0034.

    PMID: 28722637
  12. 12

    Outbreak of Schistosomiasis mansoni in a Spanish dance and percussion ensemble acquired in the Republic of Guinea.

    Arsuaga Vicente M, Ruiz-Carrascoso G, De la Calle-Prieto F, et al.

    Enfermedades infecciosas y microbiologia clinica (English ed.) 2025; (43(9)):571-576 doi:10.1016/j.eimce.2025.01.011.

    PMID: 40410036
  13. 13

    Knowledge, attitudes, and practices regarding schistosomiasis infection and prevention: A mixed-methods study among endemic communities of western Uganda.

    Anyolitho MK, Poels K, Huyse T, et al.

    PLoS neglected tropical diseases 2022; (16(2)):e0010190 doi:10.1371/journal.pntd.0010190.

    PMID: 35196328
  14. 14

    Local and International Implications of Schistosomiasis Acquired in Corsica, France.

    Gautret P, Mockenhaupt FP, von Sonnenburg F, et al.

    Emerging infectious diseases 2015; (21(10)):1865-8 doi:10.3201/eid2110.150881.

    PMID: 26401954

This page provides educational information about schistosomiasis. Always consult a healthcare provider or travel medicine specialist for the diagnosis and treatment of parasitic infections.

Stay up to date

Get notified when new research about Schistosomiasis is published.

No spam. Unsubscribe anytime.