Schistosomiasis in infants and preschool-aged children: Infection in a single Schistosoma haematobium and a mixed S. haematobium–S. mansoni foci of Niger
Graphical abstract
Schistosomiasis is frequent in infants. Prevalence of S. heamatobium and S. mansoni were respectively as high as 60.5% and 48.8%; and 28.6% are co-infected.
Introduction
Classified among the neglected tropical diseases (NTDs) (Molyneux et al., 2005, Hotez et al., 2006), schistosomiasis remains one of the most important parasitic diseases in the tropics and subtropics, and constitutes a major public health problem (van der Werf et al., 2003, Steinmann et al., 2006). Schistosomiasis is endemic in Niger, with 3–4 million people exposed, the majority of whom have Schistosoma haematobium infections (Garba and Aboubacar, 2000), but there are recent signs that Schistosoma mansoni is expanding along the Niger River Valley (NRV), probably due to water-resource developments (Steinmann et al., 2006). The main sites of transmission are the irrigated areas of the Niger River and the semi-permanent and permanent ponds (Labbo et al., 2008). Following the World Health Assembly (WHA) resolution 54.19 put forth in May 2001 (WHO, 2002), Niger is implementing a national schistosomiasis and soil-transmitted helminthiasis control programme with the support of the Schistosomiasis Control Initiative (Garba et al., 2006, Garba et al., 2009, Fenwick et al., 2009). The objective of this programme is to reduce morbidity due to schistosomiasis and soil-transmitted helminthiasis by treating at least 75% of all school-aged children and other high-risk communities where the prevalence exceeds 50% with praziquantel and albendazole, a strategy termed ‘preventive chemotherapy’ (Savioli et al., 2004, Garba et al., 2006, Garba et al., 2009).
By focusing treatment upon the school-aged population, WHA resolution 54.19 neglects children of preschool age, thus preventing them from benefiting from the praziquantel treatment given to their older peers, and hence creating a potential health inequity (Johansen et al., 2007, Stothard and Gabrielli, 2007). Root causes include the belief that very young children would not yet been exposed to infested freshwater bodies, thus an insufficient understanding and documentation of the extent and severity of schistosomiasis in this age class, and a paucity of pharmacokinetic safety data of praziquantel among young children (Allen et al., 2002, Geary et al., 2010). However, in endemic zones, women are frequently accompanied by their children, even at young age, when they go to ponds, rivers or irrigation canals, all of which may be contaminated with cercariae, the infective stage to humans. Therefore children are likely to come into contact with contaminated water at a very young age. Recent studies in Nigeria (Mafiana et al., 2003, Opara et al., 2007), Ghana (Bosompem et al., 2004) and Uganda (Odogwu et al., 2006) have shown that infection with S. haematobium and S. mansoni can indeed occur in very early childhood.
The present study pursued two objectives. First, to determine, the prevalence of schistosomiasis in children below the age of 5 years and in their mothers in a village where only S. haematobium occurred, and in a village where both S. haematobium and S. mansoni were present. The second objective was to enhance our understanding of the epidemiology of schistosomiasis and risk factors for an infection in early childhood. The results reported here shed new light on a largely neglected issue of schistosomiasis epidemiology and control and may therefore assist public health experts and disease control managers to devise adequate strategies to tackle the disease in the preschool-aged population and their mothers.
Section snippets
Study area
This cross-sectional epidemiological study was carried out in Diambala and Falmado, in the Western Sahel zone of Niger, in April 2007 (Fig. 1). The two villages have been selected after a survey in school-aged children has shown a high prevalence of schistosomiasis. Diambala (geographical coordinates: 14.313N latitude; 1.300W longitude) is located in the NRV in the department of Tillabéri, near an irrigated rice zone. The estimated population at-risk of schistosomiasis in this department is
Characteristics of study population
Table 1 summarises the demographic characteristics of the studied population, stratified by village. Overall, 282 children and 224 mothers participated in the study. The average age of the whole surveyed preschool-aged children group was 2.6 years with a standard deviation (SD) of 1.1 years. There were more girls than boys in both villages with a sex ratio of male to female of 0.89. The age of the mothers ranged from 15 to 50 years, with an average of 30.1 (SD = 8.6) years.
In Diambala, 97.8% of
Discussion
This epidemiological survey in the western part of Niger has revealed that children below the age of 5 years are at significant risk of schistosomiasis. Moreover, it is also evident that in one of the two study villages presenting as a mixed infection focus of S. haematobium and S. mansoni, young children have contracted both forms of schistosomiasis. Our study population consisted of 282 infants and preschool-aged children, and their mothers (n = 224). To our knowledge, this is the largest study
Acknowledgements
We thank the population of the villages of Diambala and Falmado for their commitment while participating in the current study. We also thank Ms Corinne Codja and all the laboratory technicians of RISEAL and the national schistosomiasis and soil-transmitted helminthiasis control programme of Niger. This investigation received financial support from the European Union (CONTRAST programme, FP6 STREP, contract no: 032203) and the Schistosomiasis Control Initiative. J. Utzinger acknowledges
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Schistosomiasis in the first 1000 days
2018, The Lancet Infectious DiseasesCitation Excerpt :However, there is substantial passive exposure to cercariae through the water-use practices of their caregivers.80 In rural Niger,75 S haematobium prevalence was 50·5–60·5% among children under 5 years, and 55·6–72·2% in their mothers, similar to other findings across Africa.76–79 One study of Ugandan preschool-age children found a mean age of first detected S mansoni infection of 17·8 months,80 and S haematobium infection in infants as young as 4 months of age has been documented in Ghana using a monoclonal antibody dipstick ELISA assay.76