1.0 Introduction
1.1 Background of the Study
Schistosomisis is a waterborne chronic human disease cause by parasitic flatworms called schistosomes. They live in the blood vessels associated with the intestine and bladder where they reproduce sexually. Schistosomiasis also known asBilharziasis is one of the most wide spread parasitic disease that put about 400 - 600 million people world wide at risk and has already infected about 200 million people. The diseases is endemic in 74 countries of the world including Nigeria, which is among the 44 African countries where the disease is highly prevalent (Ukpai & Ezeike, 2002).
Infections take place when large number of eggs are shed in the blood vessels of the intestine or urinary bladder. After rupturing these vessels, the eggs leave the body of the host via feaces or urine. When they get into water, they hatch into ciliated miracidia which bore into the tissues of certain fresh water snail (intermediate hosts). Within the snails, eachmiracidium forms spore cysts which reproduces asexually to give rise to cercariae (Raven & Johnson, 2003).
There are many known established species of schistosomiawhich commonly infect man through others,
These are:
- Schistosoma mansoni
- Schistosoma japonicum
- Schistosoma haematobium
- Schistosoma mekongi
- Schistosoma intercalatum
But the three best known species are S. mansoni, S. jap[onicum and S. haematobium (Ukoli, 2005).
S. mansoni and S. japonicum are the parasitic waterborne nematode infection that affects intestinal system and cause damage to the liver and intestinal tract and the complications arising from chronic infection are caused by a cellular reaction to the eggs in the tissues. By acquiring host antigens, the flucked are protected from host immune reactions. While S. haematobium is the blood flukes that affect urinary systems. All these flukes live in the blood vessels. Schistosomiasis has some pathogenical manifestation of rash or itchy skin, fever chills, cough and muscles aches at the early stage of one to two months. Some people, however, do not develop these symptoms at onset of infection (Ukoli, 2005).
Abdominal pain, diarrhea with blood, mucus and pus develop gradually as a result of intestinal schistosomiasis. These symptoms are caused by the body's reaction to the presence of the worms.
People are affected when swimming or are engaged in occupational activities like washing, fishing, rice farming and irrigation project in fresh water body infected with cercariae. The availability of the appropriate snail intermediate hosts helps in the spread of the disease because the miracidia cannot penetrate human skin directly without undergoing some development in the snail host (Raven & Johnson, 2003).
…
