CHAPTER ONE
1.0   INTROUDUTION    
            Schistosomiasis is also known as bilharzia or “snail fever”. It is a parasitic disease carried by fresh water snail infected with one of the five varities of the parasite schistosoma. Found predominantly in tropics and sub-tropical climates. (Chitsulo, 2000), schistosoma ranks second only to malaria as the most occurring parasitic disease in the tropics (chitsulo, 2000).
1.1                           BACKGROUND OF THE STUDY
        The schistosomes or blood flukes belong to the class trematoda of the phylum platyhelmintes. They are parasites of the blood stream of warm blooded vertebrates. The species which infect man are schistosoma haematobium, s mansoni, s intercalum and s japonicum. They cause the disease known as schistosomiasis or bilharziasis (uyaeme, 2011).
        Urinary schistosomiasis caused by fluke worm s haematobium is one of the most common tropical olisease which poses serious health hazard due to its associated morbidities. Globally, over 153 million people are infected with this parasitic infection (WHO1999). In Nigeria, a good number of foci infections have been documented in various parts of the country (Egwunyenga et al, 1994).
        In developing countries, the true epidemiological picture appears difficult because of inadequate researches in this direction despite its relevance in planning and control in any locality. This problem is compounded by the poor habits of people in developing countries in visiting hospital, for treatment. Also, self medication is still practiced as manifested by anti-helmintic abuse. This act is worsened by presence of inadequate health facilities. One of the consequences of the self-medication of the anti-helminthics abuse includes the suppression of the egg laying capacity of the worms. The net effect is erroneous diagnosis using ova in urine in any locality. This may also become evident in sub clinical cases and period of immaturity of the worms when they are yet to commence egg laying. Another obvious difficulty occurs during the early stages of infections. Although the uses of serological diagnosis are available, poverty poses a serious impediment to the applications of serology in the epidemiological work in these countries.
The spined eggs are laid in water, the eggs hatch into ciliated miracidia which bore into the tissues of certain fresh water snails, the intermediate host. Within the snail, each miracidium forms a sporocyst which reproduces asexually to give rise to cercariae (Raven and Johnson, 1996 cercariae production may continue for several weeks, over 300 being produced each day from a single sporocyst. The cercariae leaves the snail and swim in the water. They gain entry into man, the final host, by penetrating the skin. once in the body system, the cercariae develop into the adult fluke where they cause schistosomiasis.
Characteristic /features
1.  They are dioecions i.e sexes are separate and there is sexual dimorphism
2.  The male and female always occur together and the larger male carries the slender female in it’s ventral groove or gynaecophoral canal.
3.  They live in the blood stream of vertebrates.
4.  The eggs are not operculate and are usually armed with a spine.
5.  The furcocerous cercariae penetrates directly through the skin into the definitive host
6.  It is a water-borne disease with water snails as the intermediate host.
7.  There are two suckers, an oral and a ventral sucker (acetabulum).
8.  The alimentary canal consists only of intestinal caeca without an anus. (Uyaeme, 2011).