Schistosoma haematobium infection status and its associated risk factors among pregnant women in Munyenge, South West Region, Cameroon following scale-up of communal piped water sources from 2014 to 2017: a cross-sectional study

Schistosomiasis is a chronic parasitic disease caused by blood flukes of the genus Schistosoma and transmitted by snails found in fresh water bodies that have been contaminated by Schistosoma eggs. People become infected during dermal contact with water containing schistosome cercariae. In endemic areas, where there is lack of adequate water supply, poverty, ignorance and poor hygienic practices, children, women, fishermen and farmers are the high risk groups for schistosomiasis [1‐4]. Women, in particular, are more likely to be exposed to infection during activities carried out in streams such as domestic activities including washing clothes, fetching water and bathing [5, 6]. It is estimated that approximately 40 million women of childbearing age are infected with schistosomiasis, with almost 10 million infected pregnant women in Africa [1, 7]. Increasingly, findings from several studies suggest that schistosomiasis in pregnancy is an area of major public health concern [6, 8‐13].

Schistosoma haematobium is prevalent in Africa and Middle East, where the infection is causing significant morbidity and mortality when compared with S. mansoni. Schistosome eggs deposited in the wall of the urogenital bladder [14] release highly inflammatory antigens [15], triggering granuloma formation, a range of urothelial abnormalities and related signs such as haematuria, dysuria and lesions of the bladder, kidney failure and bladder cancer [16]. Several studies have reported associations between UGS and HIV [17‐19] and increasing evidence supports that it is a plausible risk factor for HIV acquisition [20]. In pregnancy, UGS has been associated with severe anaemia [1] particularly in co-infection with P. falciparum [6], maternal mortality [8, 21], premature birth and low birth weight [13, 22]. Drug-based control of morbidity related to infection has been the primary WHO strategy for schistosomiasis control, with treatment given mainly through community and school-based mass treatment with praziquantel [23]. Older age groups, including pregnant women are often left untreated. Despite recent evidence of the safety of praziquantel in human pregnancy, barriers to adopting polices for such treatment still remain [24]. Consequently, affected pregnant women can serve as reservoirs for infection bringing the distribution of the disease to pre-control level over time. More so, morbidity that builds in untreated pregnant women may result in poor pregnancy outcomes [25]. To achieve sustainable control (elimination or eradication of schistosomiasis), improvements of water, sanitation, hygiene infrastructure and modification of risk behaviour are necessary to prevent transmission of the schistosome parasite [26‐28]. The provision of safe water supply is one important approach to reduce the need for contact with contaminated water bodies and diminish the risk of schistosomiasis transmission [29].

A study carried out in 2014 in Munyenge, an endemic foci located in the mount Cameroon area, revealed that S. haematobium infection is common among pregnant women and regular contact with stream and long duration in contaminated water sources increased risk of infection. We suggested that provision of piped water and health education will decrease disease incidence and intensity [6]. More so, a recent study by Ebai et al. [30] in some neighbouring villages to Munyenge showed that access to piped water protected individuals living in these communities from UGS. Thus, following scale up of piped water supply from 2014 to 2017 in Munyenge, this study investigated the prevalence and risk factors of UGS in pregnancy for an epidemiological update. Secondly, to assess the impact of increase piped water supply, we compared stream usage, stream contact behaviour and S. haematobium infection rate and intensity with the findings of 2014.

Munyenge village is an established endemic focus for UGS. [6, 30, 36]. The establishment of safe water is an essential prerequisite for schistosomiasis control in endemic areas since, the prevention of schistosmiasis is achieved by reducing contact with schistosoma-infested water [23]. The present study is a follow-up survey which reports on the prevalence and risk factors of S. haematobium infection among pregnant women living in Munyenge, following the scale-up of communal piped water sources between 2014 and 2017. The impact of increased piped water sources was evaluated by assessing changes in stream contact patterns, prevalence and intensity of infection.

This study carried out in Munyenge, in 2017, revealed a reduced prevalence of S. haematobium infection among pregnant women by 52%. In addition, we recorded a decreased in the number of cases of heavy infection. Interestingly, our study revealed that the use of piped water eliminated the risk of infection among pregnant women who completely stopped using stream water but very little effect on those who reported partial use of safe water. Similarly, the protective role of access to piped water has been reported by Ebai et al., [30] in a survey carried out in Ikata-Likoko area which, are neighbouring communities to Munyenge in the Bafia health area. Equally, studies in other endemic areas have shown that safe water supplies were associated with significantly lower odds of schistosomiasis [29, 37‐42]. In Brazil, a communal water supply was shown to reduce the prevalence of the disease [37]. In Egypt, even the partial use of safe water markedly lowered the prevalence of S. mansoni and S. haematobium [38]. A recent study by Tanser et al. [39] reported a UGS prevalence of 16.8% following scale-up of piped water in rural South Africa which was markedly lower than the overall prevalence of 60–70% recorded in the same area thirty years earlier. Also, a cohort study carried out in the same area showed that children living in communities with a high coverage of piped water were eight times less likely to be infected relative to those living in areas with little or no access to piped water [39]. Introduction of safe water supplies into a community offers protection from schistosomiasis infection either directly or indirectly. It offers direct protection to individuals with access to safe water by reducing their contact with infested water bodies through household domestic water collection activities. Secondly, the scale-up access to safe water will confer indirect protection to members of a community in a manner that is analogous to the concept of ‘herd immunity’. Herd immunity confers protection through a reduction in the number of contacts that infected individuals have with open water bodies leading to a decrease in the overall levels of intensity of infection in the surrounding community [43].

A water supply system that is either communal or household lowers the degree of contact with infested water in a community and people change their behaviour after safe water becomes available [38, 41, 42, 44]. With increased piped water sources in Munyenge, stream usage, frequent contact with stream and prolonged duration of water contact (bathing and domestic activities in the stream) decreased significantly by 23, 69 and 37% respectively. However, in the present study, piped water usage was associated with reduced stream usage and not changes in stream contact behaviour. The change in stream contact behaviour observed may be attributed to some level of awareness on UGS in the community which, may have influenced change in attitudes of some pregnant women from bathing and washing in water bodies to stream banks or at their homes. Despite the presence of more piped water sources, a majority of the pregnant women (76%) continue to use the streams for domestic purposes. Distance from home to the taps, limited number of communal piped water sources for a dispersed population and requirement for immediate payment of piped water may account for the reliance on the stream [41, 42, 45]. It will be interesting to assess the relationship between these factors and the distribution S. haematobium infection in the study area.

Although the burden of UGS has declined in Munyenge over the indicated three-year period, the prevalence of infection still remains high (22.3%) among pregnant women. Coupled with the high rate of stream usage, other factors predisposed these women to the risk of S. haematobium infection. Marital status influenced infection outcome where single women were twice more likely to be infected with S. haematobium than their married counterparts irrespective of their age and gravidity status. The role of marital status in the risk of malaria parasite infection in pregnancy has also been reported [46]. Studies have shown that marriage has advantages on the health outcomes of individuals [47]. A spouse may improve economic well-being [48] as well as play an important role in monitoring and encouraging healthy behaviours [49]. Partner support may be important in limiting or preventing contact with infested water by the pregnant woman. Furthermore, infection was more common among individuals with low level of education. This is in conformity with findings of Lima E Costa et al. [44] and Bethony et al. [50] in Brazil, Khalid et al. [9] in Sudan and Salawu and Odiabo, [12] in Nigeria. Ugbomoiko et al. [51] suggested that education affects attitudes and behaviour. Individuals with low educational status are more likely to enter the stream barefoot and spend longer hours in water (exposing themselves to cercarial penetration) than their more educated counterparts. On the other hand, the self-awareness of the disease may account for the reduced prevalence level observed among women with at least a secondary level of education. Consistent with our previous findings in Munyenge, bathing and domestic activities in infested waters predisposed pregnant women to infection. Both activities increase intensity of water contact with infested water [6, 44, 52]. These findings strongly suggest that the extension of more piped water sources in this endemic area will reduce the incidence of infection by reducing the need for intense or frequent contact with infested water. However, a productive and sustainable intervention cannot be achieved without adequate education [52, 53]. We suggest that educating women during antenatal clinic visits on the harmful effects of UGS and the local risk factors of infection will help reduce frequency of water contact and thus infection risk in this endemic areas.

This study had a few limitations. This study examined the short-term effect of piped water supply on water contact patterns and transmission of S. haematobium infection in Munyenge. Studies have demonstrated that over long-term period, water supply facilities had little impact on the overall prevalence and intensity of infection [39, 42]. Secondly, piped water usage and stream contact behaviour were based on self- reports and not by direct observation. Analysis of spatial pattern of infection, observations of human contact at the stream and a questionnaire on water use gives a better assessment of the impact of piped supply on human water contact [39, 41, 42].