S. haematobium infection is endemic to over 50 countries in Africa and the Middle East and it is considered as a significant public health problem in much of Africa (W.H.O, 1991). It affects more than 90million people world wide, representing a major health problem in central and southern Africa and the eastern Mediterranean (Subramanian et al., 1999). Van der Werf and De Vlas (2001) gave an estimate of 111 million persons in Africa and the Middle East afflicted with the disease. The prevalence is high in Africa especially in the Nile valley where up to 95 percent of the local rural population may be infected (Smyth, 1996). Nigeria is one of the highly endemic countries where the disease has been unsystematically reported and the disease status is unknown in large areas of the country (Anosike et al., 2001).
The snail intermediate hosts are species of Bulinus, which inhabit less permanent water bodies because during their life cycle they prefer a period of aestivation (hibernation) in mud during a dry season. Recovery of B.truncatus from a well in the town of Jericho around the Jordan valley dated at 1,650 BC (Biggs, 1960) suggests that snail hosts became adapted early to human-made aquatic habitats in and around early settlement. However an early date is supported by the adaptation of schistosome parasites to primates (Platt and Brooks, 1997).
Schistosomiasis transmission takes place where the ecologies of the schistosome parasite, the aquatic snail intermediate host, and the human definitive host converge in space and time in surface waters stagnant or slow moving (Kloos and David, 2002, and appendix II). Unlike transmission of malaria and other insect-transmitted disease, schistosomiasis transmission depends on the active role of the human host, through excretory contamination of snail habitats and direct contact with infective water. This ecological relationship thus makes schistosomiasis a disease closely linked to rural water resources development, population increase, inadequate sanitation and lack of effective medical treatment (Kloos and Thompson, 1979). Species of Bulinus wade and swim in infected water. Those at high risk of infection are people involved in fishing activities, farming, bathing, paddling of canoes, swimming and possibly handling of infected snail hosts in case of collecting edible ones (WHO, 1991).
Haematuria is the one of the most striking and common manifestation of urinary schistosomiasis in endemic regions of Africa (Savioli and Mott, 1989; Lengeler et al., 1991). The pathology of urinary schistosomiasis results from host granulomatous-inflammatory response to eggs trapped in the bladder, ureters and other pelvic structures. Consequent urinary tract injury manifest as haematuria, proteinuria, bladder wall thickening and bladder irregularities (e.g. polyps, calcifications, etc.) and a predisposition to squamous cells carcinoma of the bladder (Hatz et al., 1992; King et al., 1988). Other possible consequences include dysuria, anaemia, nutritional deficiencies, kidney failure and in children growth retardation (Saathoff et al., 2004). However the pathology due to S. haematobium infection has been reviewed in detail by Jordan and Webbe (1982), and Chen and Moth (1989).
Environmental management and modification to control schistosomiasis in water resources development projects includes preventing or removing aquatic vegetation, lining canals with cement or plastic, regular fluctuating water levels and periodic rapid drying of irrigation canals. Combined with measures to prevent contaminating water bodies with urine and faeces these measures help control schistosomiasis (WHO, 1985; Pike, 1987). The provision of civilized swimming pools for recreational activities could serve as a good control measure for the spread of the disease (Gracio et al., 1992). Wearing of footwear to protect the legs could also be a good protective measure against active penetration by cercariae (the larvae) (Amano, 1990).
Chemotherapy with praziquantel currently offers the most feasible means of controlling human schistosomiasis at least in short-term (Utzinger et al., 2000; WHO, 2002). The potential problem of praziquantel resistance has led to a search for alternative drugs for the treatment and control of schistosomiasis (Doenhoff et al., 2002; Utzinger et al., 2003). Although artemisinin and its derivatives, such as artesunate, arteether, artemether and di-hydroartemisinin, were originally developed for the treatment of malaria, they have anti-schistosomal activity (Utzinger et al., 2001 a, b). Inyang-Etoh et al. (2004) cited De Clercq et al. (2002) in a related study that treatment with artesunate alone gave egg-count reduction ‘rates’ that were high and almost as good as those obtained with praziquantel.
However, in view of the paucity of information on the distribution of urinary schistosomiasis in most areas in Ile-Ife, Osun state Nigeria and the general concern that the disease may be increasing in prevalence, distribution and importance, particularly in the remote and poorly accessible rural communities, this project is undertaken to establish the occurrence, prevalence and intensity of S. haematobium infection in school-age children in two primary schools in Ile-Ife. Chi square test is adopted for statistical analysis. ...CONTINUE READING ► PAGE 3
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