Schistosomiasis is a tropical disease that is an infestation of parasitic flatworms or schistosomes that cause symptoms in humans. These flatworms live in tropical fresh water. Other names for Schistosomiasis are Bilharzia, Katayama fever, Swimmer’s itch, and Blood fluke. In order to infect human beings, the flatworms must first infect and grow to maturity inside freshwater snails. Because these snails provide a temporary home for the flatworms, they are referred to as “intermediate hosts.”
How Do Humans Get Schistosomiasis?
Infected humans pass schistosoma eggs through their urine and feces. When they urinate or defecate in fresh water where certain types of snails are living, the eggs seek out the snails. Once the eggs are inside the snails, they mature and reproduce. Then they are expelled by the snail into the water, where they can live for two days. Humans that swim in this contaminated water get schistosomiasis through skin contact with the water.
People in work activities such as rice cultivation, irrigation and fishing or people using the water for bathing and swimming become contaminated when the parasites penetrate the skin. The worms grow within the blood vessels of the human body for several weeks and also produce eggs. Half of the eggs are passed through the feces and urine. The rest of the eggs stay in the human body and cause damage and scarring to the vital organs. The symptoms of the disease are actually caused by the body’s reaction to the eggs and not the worms.
What are the Symptoms of Schitosomiasis?
In the early phase of the infection people may not experience any symptoms. If they do, however, they may develop itchy skin or a rash. After a month or two, fever, chills, muscle pain and a cough begin.
Later on, all of the symptoms are in relation to where the parasite eggs are in the body. For example, the eggs may travel to the liver or intestine or bladder and cause symptoms within these organs. Infrequently, eggs can travel to the spinal cord or the brain where they generate seizures, spinal cord inflammation or paralysis.
Diagnosis of Schitosomiasis:
Urine and stool are tested for parasites. The Center for Disease Control (CDC) offers a blood test for this purpose. It is the most accurate approximately two months after the last exposure to water that has been contaminated.
The treatment for schitosomiasis is the drug praziquantel. It is only taken for one to two days.
People who vacation in areas where flatworms are prevalent are at risk for developing schistosomiasis if they wade, swim, raft or have some other exposure to contaminated water. However, if they are exposed only briefly and are not re-exposed, their risk for complications is small – even without treatment.
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