Schistosomiasis is caused by the Schistosoma parasite, a form of parasitic worm. Various species of the Schistosoma parasite can cause illness. Schistosoma mansoni, S. haematobium, and S. japonicum are the most common cause of the disease in humans; S. mekongi and S. intercalatum are less common but can also cause illness. The disease infects more than 200 million worldwide, although the Schistosoma parasite is not found in the United States.
Here are some of the most commonly asked questions about the diagnosis, treatment, and prevention of schistosomiasis.
- How is schistosomiasis spread? The Schistosoma parasite is carried by certain types of snails. People contract the illness when they wade, swim, or bathe in freshwater inhabited by these snails. The Schistosoma parasite can survive in the water outside of its snail host for up to 48 hours and then has the ability to penetrate a person’s skin. Once inside a human host, the parasite then matures into adult worms in the infected person’s blood vessels. Female worms continue to produce eggs inside their human host; these eggs then travel to the bladder or intestines and are passed through the person’s urine or stool.
- What are the symptoms of schistosomiasis? Most people do not develop symptoms of schistosomiasis in the early stages of infection. However, some people may develop a rash or itchy skin within days of infection. Within 1-2 months of infection, people may also develop a fever, chills, cough, or muscle aches.
At later stages of infection, after the development of adult worms and the spread of eggs throughout the body, people may develop inflammation or scarring of the bladder, intestines, or liver. Long-term infection can cause permanent damage of these organs, as well as infertility. Children with chronic schistosomiasis infection can experience anemia, malnutrition, and cognitive disabilities. In rare cases, eggs can travel to the brain or spinal cord and cause seizures or paralysis.
- How is schistosomiasis diagnosed? If you have traveled to countries where schistosomiasis is found, such as countries in southern and sub-Saharan Africa or the Caribbean, and came into contact with freshwater, contact your healthcare provider immediately. Your doctor will ask you to provide a stool or urine sample to detect the parasite. Alternatively, a blood test can be used to detect infection; however, these tests are typically not accurate until at least 6-8 weeks after your last contact with contaminated water.
- How is schistosomiasis typically treated? Schistosomiasis can be easily and effectively treated with medication. Praziquantel is most commonly prescribed and is effective in treating the adult worms. For travelers, treatment should occur at least 6-8 weeks after your last exposure to contaminated water. If your doctor suspects an earlier infection, you will likely need a second course of medication within 4-6 weeks of the first dose. In areas in which schistosomiasis is common, focus is often put on large-scale preventive treatment of at-risk populations with Praziquantel. In addition, policymakers and development partners encourage improved access to safe water, improved sanitation, hygiene education, and snail control.
- How can I prevent schistosomiasis infection? There is no vaccine available for the Schistosoma parasite. If you are traveling in areas where schistosomiasis is common, you should avoid swimming, wading, fishing, or bathing in freshwater sources. While ingesting Schistosoma parasites will not lead to infection, it is possible to contract the disease through skin contact on the lips or mouth; you should also avoid drinking untreated freshwater in areas where infection is common.
- What kinds of tests are used to test for schistosomiasis? Stool and urine samples can be examined microscopically for Schisotoma eggs. However, because eggs are quite small and are passed only intermittently, these tests are not necessarily accurate. Serology tests, such as the IVD Schistosoma Serum Antibody Detection Microwell ELISA, can more accurately detect schistomiasis infection, although they are most accurate at least 6-8 weeks after infection.
Anand, Rahul. 2018. “Schistosomiasis”. Infectious Disease Advisor. Available at
Center for Disease Control (CDC). “Parasites – Schistosomiasis”. Available at
World Health Organization (WHO). “Schistosomiasis Fact Sheet”. Available at