The overall prevalence of 4.7% reported for urinary schistosomiasis in this study was less than the prevalence reported in similar studies in Nigeria and Ethiopia [10, 11, 15]. Previous studies in Galilea, peri-urban community in Ga South municipality and in the Northern region of Ghana respectively reported a prevalence of 52 and 33% for urinary schistosomiasis higher than the prevalence found in this study [6, 7]. The reduced prevalence in this study can be attributed to improvement in sanitation, the supply of safe water, awareness about the disease and the year to year administration of praziquantel to the school children in all the selected schools [15]. The high prevalence of light infection is consistent with similar studies in Nigeria and Malawi [13, 16]. The total prevalence for P. falciparum (12.9%), reported in this study was lower than the prevalence in a similar population [9]. The observed difference for P. falciparum infection could be attributed to the use of malaria prevention methods such as insecticide-treated nets and insecticides. Previous studies in same study site revealed a prevalence between 54 and 60% for urinary schistosomiasis [17]. The year to year praziquantel chemotherapy could have influenced the reduction in the prevalence of urinary schistosomiasis. Praziquantel has proven effective in reducing the prevalence and intensity of infection and risk of reinfection with S. haematobium [18].
The total prevalence of anaemia in the study was 59.9% which is indicative of a severe public health problem [19]. In Ethiopia, an anaemia prevalence of 81% was reported among children of school going age [15]. Inadequate nutritional intake, low socioeconomic status, and worm infestation are possible risk factors for the observed high prevalence of anaemia in the study.
The mean haemoglobin concentration of the study population was 11.6 ± 1.5 g/dl. This is because the prevalence of mild anaemia was higher than the prevalence of moderate and severe anaemia. This finding is similar to other studies among children of school going age [9, 20].
Although haemoglobin concentration of P. falciparum infected children was lower than S. haematobium infected respondents, malaria was not a discriminatory factor to anaemia. This could be attributed to the high endemicity of P. falciparum among the study respondents resulting in misclassification. Children who were lightly infected with S. haematobium had a higher haemoglobin concentration because they are less likely to have haematuria. The Plasmodium parasites break down red blood cells and increase the clearance of both infected and uninfected red blood cells and a reduction in erythropoiesis [21]. Similar findings of a higher risk of lower hemoglobin concentration with P. falciparum infection was reported in Nigeria [10]. Respondents with light infection had a significantly higher haemoglobin concentration compared with respondents with heavy infection (p-value < 0.05) thus contributing to the higher haemoglobin concentration in S. haematobium infected respondents. The intensity of S. haematobium infection is positively correlated with hemoglobin concentration [15].
All respondents with coinfection had anaemia. In Ethiopia children with concurrent S. haematobium and P. falciparum infection had a lower hemoglobin concentration than children with mono-infection [15]. The concurrent infection with both parasites may have enhanced their risk of anaemia in the children who were co-infected.
The reported prevalence of hookworm infection in Ghana ranges from 3.2 to 10% [22, 23]. There is currently on-going helminth control program in the two districts. School children are given albendazole treatment for worm infection and praziquantel administration for schistosomiasis. Helminthic infestation particularly hookworms can lead to anaemia. Though the study did not assess the nutritional status and prevalence of helminthic infections, anaemia due to the worm infestation is unlikely given the ongoing interventions in the area.
Further studies, taking into consideration, these confounders should be carried to obtain the true relationship between these risk factors and haemoglobin concentration in school children. This is necessary to understand the causes of the high levels of anaemia for the formulation of appropriate public health intervention.