Causes and Transmission
Schistosomiasis is caused by parasitic flatworms known as blood flukes (genus Schistosoma). The infection cycle begins when people contaminate freshwater sources with urine or feces containing parasite eggs. These eggs hatch and release larvae that infect specific types of freshwater snails. Inside the snails, the parasite develops into a form that can swim freely in the water. People become infected when they come into contact with this contaminated freshwater, as the microscopic parasites can penetrate healthy human skin.

Risk Factors
Living in or traveling to tropical and subtropical areas where the disease is common increases the risk of infection. Specific behaviors and environmental factors include:

• Swimming, bathing, or wading in freshwater lakes, ponds, or rivers.
• Working in occupations such as fishing, rice farming, or irrigation labor.
• Lack of access to clean drinking water and adequate sanitation facilities.
• Washing clothes or domestic items in infested water sources.

Primary Prevention
The most effective way to prevent schistosomiasis is to avoid all contact with freshwater in areas where the disease is known to occur. Safe alternatives include swimming in the ocean or in chlorinated pools, as the parasites cannot survive in salt water or properly treated water. If water from a freshwater source must be used for bathing, it should be boiled for at least one minute or allowed to sit in a storage tank for 24 to 48 hours before use, as the parasites die without a host within that timeframe.

Reducing Severity
While there is no vaccine available, mass drug administration programs in endemic regions help reduce the burden of disease. For travelers who may have been exposed, vigorous towel drying immediately after leaving the water may potentially prevent some parasites from penetrating the skin, though this method is not reliable and should not replace avoidance strategies.

Signs and Symptoms
Symptoms of schistosomiasis are caused by the body's reaction to the worm's eggs rather than the worms themselves. Many people do not experience symptoms immediately. When symptoms do occur, they typically follow a progression:

• Early signs: Within days of infection, a rash or itchy skin may appear at the site where the parasites entered the body, often called "swimmer's itch."
• Acute phase: Several weeks later, a syndrome known as Katayama fever may develop, causing fever, chills, cough, muscle aches, and fatigue.
• Chronic phase: Without treatment, symptoms persist for years and vary based on the location of the infection. Intestinal schistosomiasis causes abdominal pain, diarrhea, and blood in the stool. Urogenital schistosomiasis commonly presents as blood in the urine, painful urination, and pelvic pain.

Diagnostic Tests
Clinicians identify the condition by detecting parasite eggs in samples of stool or urine. The choice of sample depends on whether the symptoms suggest intestinal or urinary infection. For travelers or those with light infections, blood tests are often used to detect antibodies against the parasite. These blood tests are most accurate when performed at least 6 to 8 weeks after the last exposure to contaminated water.

Differential Diagnosis
The symptoms of schistosomiasis can resemble other tropical diseases. It is often confused with malaria, typhoid fever, or bacterial infections of the urinary tract and intestines. Proper testing is essential to distinguish it from these conditions and ensure the correct treatment is prescribed.

Medical Treatment
The primary treatment for all forms of schistosomiasis is a prescription medication called praziquantel. This drug is effective at killing the adult worms responsible for laying eggs. It is usually taken as a pill in one or two doses on a single day. In some cases, a follow-up dose may be required a few weeks later to ensure all parasites are eliminated, particularly because the medication is most effective against adult worms and may miss developing larvae.

Symptom Management
Supportive care may be needed to manage the complications of the disease. This can include staying hydrated and treating anemia if blood loss has occurred. In cases where the infection has caused significant inflammation or allergic reactions (such as Katayama fever), doctors may prescribe corticosteroids to reduce swelling and improve comfort during treatment.

When to Seek Medical Care
Individuals who have traveled to areas where schistosomiasis is found (such as parts of Africa, South America, or Asia) and have had contact with freshwater should consult a healthcare provider. Immediate medical attention is recommended if any red-flag symptoms appear:

• Visible blood in the urine or stool.
• Persistent fever, cough, or muscle aches after travel.
• Unexplained abdominal pain or swelling.
• Seizures or signs of confusion (rare, indicating potential nervous system involvement).

Severity and Complications
Schistosomiasis ranges from mild, asymptomatic cases to severe, disabling disease. The severity usually depends on the number of worms present and the duration of the infection. If left untreated for years, the chronic immune response to trapped eggs can cause permanent damage. Complications may include scarring (fibrosis) of the liver, enlarged spleen, and high blood pressure in the liver's blood vessels. In the urinary form, chronic inflammation can lead to bladder wall scarring, kidney obstruction, and an increased risk of bladder cancer.

Prognosis and Disease Course
With early diagnosis and treatment, the prognosis is excellent, and most patients recover completely without lasting effects. Treatment can often reverse early-stage organ damage, such as inflammation in the liver or bladder. However, advanced scarring (fibrosis) is generally irreversible. Reinfection is possible if a person is exposed to contaminated water again, so repeated treatment may be necessary for people living in high-risk areas.

Long-term Effects
In children, repeated infections can cause anemia, stunted growth, and learning difficulties due to chronic poor health. In women, urogenital schistosomiasis can cause lesions in the reproductive tract, which is associated with complications during pregnancy and an increased susceptibility to other infections.

Impact on Daily Activities
During the acute phase, symptoms like fever and fatigue can make work or school difficult. Chronic infection often causes a general sense of unwellness, lethargy, and reduced physical endurance, which can affect productivity and participation in daily tasks. Children with the condition may experience difficulty concentrating in school due to anemia and malnutrition associated with the parasite.

Coping and Support
Managing the condition involves completing the full course of medication and adhering to follow-up testing. Patients should focus on maintaining good nutrition to help the body repair any damage. Support is largely practical, focusing on understanding how to avoid reinfection by changing water-contact habits.

Questions to Ask Your Healthcare Provider
Patients should feel empowered to ask questions to better understand their care plan. Useful questions include:

• How long will it take for the medication to eliminate the infection?
• Do I need to be retested after treatment to ensure the parasites are gone?
• Are my family members at risk if we traveled together?
• Is there any permanent damage to my liver, bladder, or kidneys?
• When is it safe for me to return to normal physical activities?

Q: Is schistosomiasis contagious from person to person?
A: No, you cannot catch schistosomiasis directly from another person. The parasite requires a specific freshwater snail to complete its life cycle before it can infect humans.

Q: Can I get schistosomiasis from a swimming pool?
A: No, you cannot get the infection from a swimming pool as long as the water is chlorinated and well-maintained.

Q: How long after exposure do symptoms appear?
A: Symptoms vary; a rash may appear within days, while fever and muscle aches typically develop 2 to 8 weeks after infection. Some people may not show signs for months.

Q: Is there a vaccine to prevent this condition?
A: Currently, there is no vaccine available for schistosomiasis, so prevention relies on avoiding contact with potentially contaminated fresh water.

Q: Can the ocean or salt water transmit the disease?
A: No, the parasites that cause schistosomiasis can only survive in fresh water, so swimming in the ocean is safe.