Diseases Transmitted through Parasitic Worms in Snails
Most Important Snail-Transmitted Disease:
What is schistosomiasis?
Schistosomiasis, also known as Bilharzia, is a parasitic disease caused by worms. The three main species infecting humans are Schistosoma haematobium, S. japonicum, and S. Mansoni. Two other species, less localized geographically, are S. Mekongi and S. Intercalatum.
How can I get schistosomiasis?
Infection occurs when your skin comes in contact with contaminated freshwater in which certain types of snails that carry schistosomiasis are living.

Freshwater becomes contaminated by Schistosoma eggs when infected people urinate or defecate in the water. The eggs hatch, and if certain types of freshwater snails are present in the water, the parasites develop and multiply inside the snails. The parasite leaves the snail and enters the water where it can survive for about 48 hours.
Schistosoma parasites can penetrate the skin of persons who are wading, swimming, bathing, or washing in contaminated water. Within several weeks, parasite mature into adult worms, residing in the blood vessels of the body where the females produce eggs. Some of the eggs travel to the bladder or intestine and are passed into the urine or stool.

What are the signs and symptoms of schistosomiasis?

  • Within days after becoming infected, you may develop a rash or itchy skin.
  •  Fever, chills, cough, and muscle aches can begin within 1-2 months of infection.
  •  When adult worms are present, the eggs that are produced usually travel to the intestine, liver or bladder, causing inflammation or scarring.
  • Children who are repeatedly infected can develop anemia, malnutrition, and learning difficulties. 
  •  After years of infection, the parasite can also damage the liver, intestine, lungs, and bladder.
How is schistosomiasis diagnosed?
Your health care provider may ask you to provide stool or urine samples to see if you have the parasite. A blood sample can also be tested for evidence of infection. For accurate results, you must wait 6-8 weeks after your last exposure to contaminated water before the blood sample is taken.
What is the treatment for schistosomiasis?
Safe and effective drugs are available for the treatment of schistosomiasis. Praziquantel is the recommended treatment drug. See your doctor for appropriate diagnosis and treatment.
Am I at risk?
If you live in or travel to areas where schistosomiasis occurs and your skin comes in contact with freshwaters from canals, rivers, streams, ponds, or lakes, you are at risk of getting schistosomiasis.
How can I prevent schistosomiasis?
  • Dry your skin thoroughly after exposure to water in areas affected by the disease.
  •  Do not swim or defecate in ponds or standing water. 
  •  Combat snail-borne schistosomiasis. 
  •  Maintain personal hygiene and use clean water for drinking or bathing. 
  •  Get rid of wastes away from water sources. 
  •  Bath water should be heated to a rolling boil for at least 1 minute. Water held in a storage tank for at least 1-2 days should be safe for bathing.
Last Update : 15 May 2014 04:09 PM
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