Summary about Disease
Schistosomiasis, also known as bilharzia or snail fever, is an acute and chronic parasitic disease caused by blood flukes (trematode worms) of the genus Schistosoma. Humans become infected when larval forms of the parasite, released by freshwater snails, penetrate the skin during contact with infested water. The parasites then migrate through the body, maturing and residing in blood vessels of the intestines or bladder. The eggs produced by adult worms are released in feces or urine, completing the parasite's life cycle if they reach freshwater. Schistosomiasis is most prevalent in tropical and subtropical areas, especially in poor communities without access to safe drinking water and adequate sanitation.
Symptoms
Symptoms of schistosomiasis can vary depending on the species of Schistosoma involved and the stage of infection. Many people, especially in early stages, may have no symptoms. Acute schistosomiasis (Katayama fever) can occur weeks after initial infection, with symptoms including fever, cough, abdominal pain, diarrhea, headache, and rash. Chronic schistosomiasis can lead to more serious complications, including abdominal pain, enlarged liver and spleen, blood in the stool or urine, and problems passing urine. In severe cases, it can cause liver damage, kidney failure, infertility, or bladder cancer. In children, schistosomiasis can cause anemia, malnutrition, and learning difficulties.
Causes
Schistosomiasis is caused by parasitic worms called schistosomes. The infection occurs when the skin comes into contact with contaminated freshwater in which certain types of snails that carry schistosomes are living. The parasites penetrate the skin, enter the bloodstream, and migrate to the liver, where they mature into adult worms. The adult worms then move to their preferred location in the body (either the blood vessels around the intestines or the bladder) and begin to lay eggs. Some of these eggs are passed out of the body in the feces or urine, while others become trapped in body tissues, causing inflammation and organ damage.
Medicine Used
4. Medicine used The primary medication used to treat schistosomiasis is praziquantel. It is effective against all species of Schistosoma. Praziquantel works by paralyzing the worms, making them dislodge from the blood vessels and be cleared by the body's immune system. The dosage is typically based on body weight. Single or multiple doses may be prescribed, depending on the severity of the infection and the *Schistosoma* species. Other medications may be used to manage complications, such as corticosteroids for severe inflammatory reactions or antibiotics for secondary bacterial infections.
Is Communicable
Schistosomiasis is not directly communicable from person to person. Transmission requires the presence of specific freshwater snails that act as intermediate hosts for the parasite. Humans become infected when they come into contact with water containing the larval form of the parasite (cercariae) released by these snails.
Precautions
Avoid swimming or wading in freshwater in areas where schistosomiasis is known to occur. If contact is unavoidable, vigorous towel drying after exposure may reduce the risk of penetration by the parasite, though this is not foolproof.
Drink safe water: Boil water for at least 1 minute or filter it with a high-quality filter to remove parasites.
Improve sanitation: Proper disposal of human waste prevents eggs from reaching freshwater sources.
Control snails: Public health programs may use molluscicides to control snail populations in infested areas.
Educate communities: Raising awareness about schistosomiasis and how to prevent it is crucial.
Treatment: Mass drug administration programs can help reduce the burden of schistosomiasis in endemic areas.
How long does an outbreak last?
There is no outbreak for the disease. Schistosomiasis is endemic in certain regions, meaning it is constantly present in the population. Individual infections last until treated, and reinfection is possible with further exposure to contaminated water. The duration of an acute infection (Katayama fever) can last for several weeks. Chronic schistosomiasis can persist for years or even decades if left untreated, leading to progressive organ damage.
How is it diagnosed?
Schistosomiasis is typically diagnosed by identifying Schistosoma eggs in stool or urine samples. Multiple samples may be needed, as egg shedding can be intermittent. Other diagnostic tests include:
Serology: Blood tests to detect antibodies against Schistosoma. These tests can be useful, especially in early infections or when eggs are difficult to find.
PCR (Polymerase Chain Reaction): Detects parasite DNA in samples.
Ultrasound: To assess organ damage, such as liver or spleen enlargement.
Rectal or bladder biopsy: In some cases, a biopsy may be performed to confirm the diagnosis and assess the extent of tissue damage.
Timeline of Symptoms
9. Timeline of symptoms
Initial penetration: Itching or a mild rash at the site of penetration may occur within days.
Acute Schistosomiasis (Katayama fever): 2-12 weeks after initial infection. Symptoms: Fever, cough, abdominal pain, diarrhea, muscle aches, fatigue, headache, rash.
Chronic Schistosomiasis: Develops over months to years. Symptoms: Abdominal pain, blood in stool or urine, enlarged liver and spleen, problems passing urine, anemia, malnutrition. The specific symptoms and their severity depend on the Schistosoma species and the organs affected.
Late-stage complications: May develop many years after initial infection, leading to organ failure, infertility, or cancer.
Important Considerations
Travel history: Consider schistosomiasis in the differential diagnosis of patients with compatible symptoms who have traveled to endemic areas.
Co-infections: Schistosomiasis can increase susceptibility to other infections, such as HIV.
Children: Children are often at higher risk of infection due to their tendency to play in water.
Pregnancy: Schistosomiasis can affect pregnancy outcomes. Treatment with praziquantel is generally considered safe during pregnancy but should be discussed with a healthcare provider.
Re-infection: Even after successful treatment, re-infection is possible with repeated exposure to contaminated water. Prevention measures are crucial.
Public Health Importance: Schistosomiasis is a significant public health problem in many developing countries. Control programs focus on mass drug administration, snail control, and improved sanitation.