August 19, 2006

 Studies on Schistosoma haematobium... ( Cont.. 3)

LITERATURE REVIEW
Cases of Schistosoma haematobium infection, the dominant form of human schistosomiasis in Nigeria, are frequently encountered in schools, hospitals and clinics in various parts of this country (Edungbola et al., 1988). School age children usually present the highest prevalence and intensity of S. haematobium infections (Jordan et al., 1993): Review on S. haematobium infection or otherwise urinary schistosomiasis in school children is large, but early reports of S. haematobium infections in Ile-Ife are limited. Nonetheless studies on the disease have been carried out by researchers in other parts of Nigeria, Africa and around the world.

Amole and Jinadu (1994) conducted a study on urinary schistosomiasis among 553 randomly selected primary and secondary school children in Ile-Ife township in 1988.The report showed that nearly half (48.5%) of the school children were infected. There was a sharp increase in both prevalence and intensity of the infection up to age 13 years, which then declined slightly by age 14. Moreso, about 50% of the infected school children had gross haematuria and there was an association between the intensity of infection and the presence of haematuria. In a report conducted by Adewunmi et al. (1990) in Ile-Ife, showed that the transmission of S. haematuria in a stream only occurred in the dry-season.

Knowledge, Attitudes, practices and Beliefs study was conducted by Onayade et al. (1996) among primary school children (those with more than four years elementary education) in Ogbagba village Osun state, Nigeria, from October 1990 to December 1993 to ascertain their understanding of urinary schistosomiasis. The study further assessed the potential of subjective haematuria, i.e. asking the children with haematuria in the recent past to so indicate in detecting urinary schistosomiasis. It was established that subjective haematuria is both sensitive and specific for detecting urinary schistosomiasis in endemic communities. Interviews with physical and laboratory examination of 106 grade 4-6 pupils aged 8-16 were conducted. 
Eighty-nine point five percent of the children had urinary schistosomiasis, 75.5% of all pupils knew the local name for urinary schistosomiasis, 66% had previously passed blood in their urine, 85.7% of these pupils believed haematuria was serious, 70.8% gave a positive history of current episode of haematuria and 65.7% of all pupils did not know what caused urinary schistosomiasis. While 67.1% believed that urinary schistosomiasis was acquired via some form of contact with water especially swimming (57.1%). Still on report of Onayade et al. (1996); the leading types of water contact included washing (95.3%), fetching water (94.3%), bathing (87.7%) and swimming (74.5%). And in addition, 74.5% of all pupils urinated deliberately in the river. This survey conducted by Onayade et al. (1996), confirmed high prevalence of the disease amongst school pupils in Osun state from 1990 to 1993.

Adewunmi et al. (1991) found the prevalence of S. haematobium in school children aged 5-16 years in 3 communities in southwest Nigeria to be 76.2, 70.3 and 66.4% respectively. The percentage of infected children harbouring heavy infections (greater than 50 eggs/10ml urine) in the 3 communities was 75.5, 69.2, and 48.1% with a prevalence of visible haematuria among the heavily infected children of 29.5, 19.4 and 24.3% respectively. Moreso, Adewunmi et al. (1993) in a cross sectional survey of schistosomiasis, intestinal parasites and pattern of schistosomiasis transmission in four rural villages around the Erinle dam, Nigeria found the prevalence of S. haematobium to range from 10% to 60%. Thirty percent of infected school children excreted over 50 eggs/10ml urine and high rates of haematuria, proteinuria, leucocyturia and nitrites in urine were observed in infected children and the villagers. 

Further still on S. haematobium infection in the southwest, Okoli and Odaibo (1999) reported a prevalence of 22.4% in post primary school children and 12.0% in primary school children in Ibadan. Of 1331 children examined for eggs of S. haematobium in their urine, 17.4% were infected. Boys had a significantly higher prevalence in males (24.1%) than girls (8.5%), and the intensity of infection was also higher in males (39.0 eggs/10ml urine) than in the females (22.1 eggs/10ml urine). Water contact activities were more frequent in males (61.8%) than females (38.2%). 

In a related study in Ibadan North local Government Area conducted by Adeyeba and Ojeaga (2002) between August and December 1998 among school children showed that there is a linear relationship between water contact / usage and infection rate. And of 1600 pupils examined, 920(57.5%) had the Ova of S. haematobium in their urine. Furthermore according to Arinola (1995) in a study carried out in Ibadan on 218 school children aged 6-15 years, on 38 local dry cleaners aged 25-47 years, and on 57 vehicle washers aged 18-28 years; the prevalence and intensity of urinary schistosomiasis is directly dependent on frequency and duration of water contact and age, but independent of sex. Of the 3 categories examined for urinary schistosomiasis, school children had the highest prevalence (21.1%). Males among school children and vehicles washers were more infected at 24.8% and 15.8% respectively.

Among 830 inhabitants of Ikao Village, in Owan Local Government Area of Edo state, 178 (21.4%) excreted S. haematobium ova in their urine. school children were more infected than the farmers and petty traders. Males were more infected than the female counterparts (Nimorsi et al., 2001 a). In a related study conducted by Nimorsi et al. (2001 b) in Owan East local Government area of Edo State, it was reported that the urine pattern of infection was also high among the school children compare to other inhabitants of the communities among which the survey was carried out.

Edungbola (1980) in Ilorin reported the relationship between water utilization and schistosomiasis. While Okanla (1991), reported that parental occupation may be a factor in contracting schistosomiasis. Moreover, in the Babana district of Borgu Local Government Area of Kwara state, Edungbola et al. (1988) stated that of 425 schoolchildren examined in nine communities, 193(45.4%) were infected. Infection rates for boys and girls (44.7% and 47.9% respectively) were not significantly different. The portion (25.9%) of children excreting at least 1000 eggs/10ml urine sample during their first decade of life was significantly higher (p<0.01) than for pupils who were older. Children between 11 years and 13 years of age had the highest prevalence (59.2%). While those between 5 years and 7 years had the lowest (33.6%). Similar trends were observed in Malumfashi, Northern Nigeria (Pugh and Gilles, 1979), in Ijimar, South-eastern Nigeria (Ekanem et al., 1994), in Uniweze-Anam, Anambra state (Amazigo et al., 1997), and in Abia state (Nduka et al., 1995; Useh and Ejezie 1999).

Ernould et al. (2000) recorded a global prevalence of 15.7% in a cluster sample survey conducted in 1998 in 30 schools in Niamey, Niger. The prevalence was very low in schools far from the river and higher in those along the Niger banks. Forty-six percent of the children reported water contact. Mansour et al. (1981) recorded an overall prevalence of the infection in school children (5-16 years old) in three villages; of Qena governorate in upper Egypt as 61.1% based on the examination of urine sample. It was found that age prevalence and intensity of infection were parallel and rose sharply from age 5-10 years. Similar studies on school children in selected villages in Ghana (Zijlmans et al., 1989), Gabon (Van Etten et al., 1997), Maputo in Mozambique (Gujral and Vaz, 2000), Cameroon (Ndamukong et al., 2001), Somalia (Arfaa, 1975) and in Zimbabwe (Ndamba et al., 1998) showed that infection rates were higher between ages 11 to 12 years than in children 7 to 10 years of age. Male school children were more significantly infected than their female counterparts.

 Moreso, Ndamba et al. (1998), Guyatt et al. (1999), Lucien et al. (2003) and among others found a positive correlation between the questionnaire approach to determine urinary schistosomiasis, the biochemical testing and ova detection rate in the first phase of the study conducted among school children in endemic rural communities of Cameroon, Tanzania and Zimbabwe respectively. Several other studies from other parts of Africa like Togo, Chad, Ethiopia, Cote de Voire and Arabian Peninsula showed similar results. Samuel et al. (2000) in Britain showed that terminal urine samples taken after exercise at midday were positive for S. haematobium ova. Dysuria and haematuria was noted 2-3 months after the infection. However all patients were from Africa and had recently visited their native country.

In summary this review has shown the diverse forms of approach to the study of S. haematobium infection. Results and records have revealed the occurrence of the parasite in various parts of the world most especially in Africa and the Middle East.
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