Schistosomiasis (also known as bilharzia) is a parasitic disease caused by Schistosoma worms. The infection occurs when larvae from freshwater snails penetrate human skin, leading to chronic inflammation and organ damage, primarily affecting the intestines, liver, bladder, and urinary tract.
It is one of the most common parasitic diseases in tropical and subtropical regions, particularly in Africa, South America, the Middle East, and Southeast Asia.
Causes & Transmission (Life Cycle of Schistosoma Worms)
1️⃣ Eggs Are Released into Freshwater – Infected people pass Schistosoma eggs in urine or feces into lakes, rivers, or ponds.
2️⃣ Eggs Hatch into Miracidia Larvae – These infect freshwater snails, where they develop into cercariae (infectious larvae).
3️⃣ Cercariae Penetrate Human Skin – While swimming, bathing, or walking in contaminated water, larvae burrow into the skin and enter the bloodstream.
4️⃣ Parasites Mature in the Bloodstream – Schistosomes develop into adult worms (1-2 cm long) inside blood vessels near the bladder, intestines, or liver.
5️⃣ Eggs Cause Chronic Inflammation – Female worms release eggs that trigger immune reactions, scarring, and organ damage.
6️⃣ Eggs Exit the Body & Continue the Cycle – Some eggs are excreted in urine or feces, continuing the cycle if they reach water.
💡 Humans become infected through direct skin contact with contaminated freshwater. There is no person-to-person transmission.
Types of Schistosomiasis & Symptoms
🔹 Intestinal Schistosomiasis (Schistosoma mansoni, S. japonicum, S. mekongi, S. intercalatum)
- Affects the intestines & liver
- Symptoms: Diarrhea, blood in stool, abdominal pain, liver enlargement, malnutrition
🔹 Urinary Schistosomiasis (Schistosoma haematobium)
- Affects the urinary tract & bladder
- Symptoms: Blood in urine (hematuria), painful urination, kidney damage, bladder cancer risk
🔹 Cerebral (Brain) Schistosomiasis
- Rare but severe; occurs when eggs reach the brain
- Symptoms: Seizures, headaches, confusion, paralysis
🔹 Acute Schistosomiasis (Katayama Fever)
- Occurs weeks after initial infection
- Symptoms: Fever, rash, muscle pain, chills, swollen lymph nodes
💡 Chronic schistosomiasis can cause long-term organ damage if left untreated.
Diagnosis of Schistosomiasis
✅ Stool or Urine Examination – Detects Schistosoma eggs in feces or urine samples.
✅ Blood Tests (Serology/Antibody Tests) – Detects antibodies against Schistosoma worms.
✅ Ultrasound or MRI (for Chronic Cases) – Checks for liver, bladder, or kidney damage.
✅ Cystoscopy (Bladder Schistosomiasis) – Examines bladder walls for lesions.
💡 Early diagnosis prevents severe complications like liver fibrosis, kidney failure, or bladder cancer.
Treatment of Schistosomiasis
💊 Praziquantel (PZQ) – The primary drug used to kill adult Schistosoma worms.
💊 Corticosteroids (for severe cases) – Reduce inflammation and allergic reactions to dying worms.
💊 Iron Supplements & Nutrition Support – Helps recover from anemia and malnutrition caused by chronic infection.
🚨 Without treatment, schistosomiasis can lead to permanent organ damage.
Prevention & Control Strategies
✔ Avoid Swimming in Contaminated Water – Freshwater in endemic areas may contain Schistosoma larvae.
✔ Improve Sanitation & Hygiene – Proper disposal of human waste (urine & feces) prevents water contamination.
✔ Snail Control Programs – Reducing freshwater snail populations helps break the cycle of infection.
✔ Mass Drug Administration (MDA) Programs – Periodic Praziquantel treatments for at-risk populations in endemic regions.
✔ Wear Protective Clothing & Footwear – Minimizes skin exposure to infected water.
✔ Safe Drinking Water Practices – Boiling or filtering water reduces risk.
💡 Eradication of schistosomiasis requires community-wide treatment, improved sanitation, and public health education.
Schistosomiasis & Global Impact
🌍 Over 200 million people worldwide are infected, mostly in sub-Saharan Africa.
🚸 Children are most affected due to playing in contaminated water.
🧑⚕️ A major cause of chronic illness – Contributes to malnutrition, anemia, and organ failure in endemic regions.
🎗️ Bladder Cancer Link – Long-term Schistosoma haematobium infections increase bladder cancer risk.
💡 Schistosomiasis is classified as a Neglected Tropical Disease (NTD), meaning it primarily affects low-income regions with poor sanitation.
Final Thoughts
Schistosomiasis is a parasitic disease spread through contaminated freshwater, leading to intestinal, liver, bladder, and kidney damage. Early treatment with Praziquantel is highly effective, and prevention relies on sanitation, snail control, and avoiding contaminated water.