Schistosomiasis, also known as Bilharzia, Bilharziosis, Katayama’s Fever, Snail Fever, and Swimmer’s Itch, is a disease caused by several species of parasitic flatworm (called Schistosome).
The disease primarily affects people Africa, South America, the Caribbean, the Middle East, and east Asia. It is estimated that approximately 200 million people are currently infected with the disease world wide, but only 120 million of these show any symptoms.
The symptoms of Schistosomiasis can be very debilitating and include:
- Abdominal pain
- Central nervous system lesions
- Colonic polyposis with bloody diarrhea
- Intestinal damage
- Liver enlargement / damage
- Spleen enlargement
- Ureteritis, which can progress to bladder cancer
Cause and Transmission
Schistosomiasis is caused by infection of the blood by any of several species of parasitic flatworm (called Schistosome).
Schistosomiasis is caused by several species of parasitic flatworm (called Schistosome), which are found in water that contains fresh water snails (of the genus Biomphalaria, Bulinus, or Oncomelania) which are themselves infected with the parasite.
These snails are natural reservoirs for the disease.
The most common way of becoming infected with Schistosomiasis is by wading or swimming in fresh water which contains large numbers of snails which are infected with the parasite.
Schistosomiasis is easily treated with just a single oral dose of the medication Praziquantel, which is a safe and highly effective treatment. However, Praziquantel does not prevent re-infection, so it is not the ideal treatment for people living where the Schistosomiasis parasite is common.
Research is continuing into developing new and improved treatments for Schistosomiasis, including the development of a vaccine that will prevent the parasite from completing its life cycle in humans, and new medications, such as Oxamniquine and Mirazid. Castor oil has also been found to prevent oral infection by the Schistosomiasis parasite.
Prevention and Control
The following techniques are used to attempt to prevent and control Schistosomiasis:
- Personal Protection: is accomplished by avoiding wading or swimming in bodies of fresh water, such as lakes and ponds, which are or may be infested with the snail.
- Snail Eradication: the primary prevention measure is the eradication of the fresh water snails (of the genus Biomphalaria, Bulinus, or Oncomelania) which are natural reservoirs for the disease. This accomplished by identifying bodies of fresh water, such as lakes and ponds, which are infested with the snail, and :
- Adding chemicals to the water which kill the snails, such as acrolein, copper sulfate, niclosamide, and so on.
- The Gopo Berry and the Sapindus Plant (Phytolacca dodecandra), may also provide a natural, environmentally friendly way to kill or control the snail.
- Recent studies suggest that snail populations can be controlled by the introduction of fresh water crayfish, providing a natural, environmentally friendly way to kill or control the snail.
- Construction Techniques: since the 1950s, specifications and design criteria have been made available by the United Nations (UN) which show how dams, irrigation schemes, and similar projects an be constructed so that they are not suitable habitats for the snails and also make it more difficult for the local population to come into contact with the water. Unfortunately, many projects have been completed without taking these specifications and design criteria into account.