Schistosoma mansoni among pre-school children in Musozi village, Ukerewe Island, North-Western-Tanzania: prevalence and associated risk factors

Abstract

BackgroundRecent evidence indicates that pre-school children (PSC) living in S. mansoni highly endemic areas are at similar risk of schistosomiasis infection and morbidity as their school aged siblings. Recognizing this fact, the World Health Organization (WHO) is considering including this age group in highly endemic areas in control programmes using mass drug administration (MDA). However, detailed epidemiological information on S. mansoni infection among PSC is lacking for many endemic areas, specifically in Tanzania. This study was conducted to determine the prevalence of S. mansoni infection and its associated risk factors among PSC in Ukerewe Island, North-Western Tanzania.MethodsThis was a cross-sectional study, which studied 400 PSC aged 1–6 years. The Kato-Katz (K-K) technique and the point of care circulating cathodic antigen (CCA) immunodiagnostic test were used to diagnose S. mansoni infection in stool and urine samples respectively. A pre-tested questionnaire was used to collect demographic data and water contact behaviour of the children from their parents/guardians.ResultsBased on the K-K technique, 44.4 % (95 % CI: 39.4–49.4) pre-school children were infected with S. mansoni and the overall geometric mean eggs per gram of faeces (GM-epg) was 110.6 epg with 38.2 and 14.7 % having moderate and heavy intensity infections respectively. Based on the CCA, 80.1 %, (95 % CI: 76.0–84.0) were infected if a trace was considered positive, and 45.9 %, (95 % CI: 40.9–50.9), were infected if a trace was considered negative. Reported history of lake visits (AOR = 2.31, 95 % CI: 1.06–5.01, P < 0.03) and the proximity to the lake shore (<500 m) (AOR = 2.09, 95 % CI: 1.05–4.14, P < 0.03) were significantly associated with S. mansoni infection. Reported lake visit frequency (4–7 days/week) was associated with heavy intensities of S. mansoni infection (P < 0.00).ConclusionThe prevalence of S. mansoni infection in the study population using K-K and CCA-trace-negative was moderate. The frequency of lake visits and the proximity to the lake shore were associated with the infection of S. mansoni and its intensity. These findings call for the need to include the PSC in MDA programmes, public health education and provision of safe water for bathing.

Intestinal schistosomiasis and the associated transmission factors in pre-school aged children in villages surrounding Lake Rweru in Bugesera District, Rwanda

“…Schistosomiasis control programs have been undertaken in Rweru area since 2010 (Rwanda Ministry of Health, 2010). The low prevalence of S. mansoni infection observed in the Rweru area, Rwanda among the PSAC in the current study differs from the results of similar studies conducted elsewhere, within the sub-Saharan region, and where prevalence with the Kato-Katz procedure was in the range 7-44% and with the CCA test, was 40-80% (Coulibaly et al, 2013;Odogwu et al, 2006;Ruganuza et al, 2015).…”

“…Interestingly, there was a significant association between infection with S. mansoni and going to the lake by the PSAC especially when the children accompany their parents/guardians or older children to the lake. The similar findings have been reported in western Kenya and in Tanzania (Handzel et al, 2003;Ruganuza et al, 2015).…”

Schistosoma, other helminth infections, and associated risk factors in preschool-aged children in urban Tanzania

“…We did not find any association between helminth infections and commonly reported risk factors such as age, hygiene, low socioeconomic status, and history of migration. This is in contrast to other studies, which identified age, poor hygiene, and low socioeconomic status as risk factors for helminth infection in children [ 16 , 17 , 35 , 45 ]. The lack of association with risk factors might be in part due to our sampling strategy, which was primarily powered to detect the prevalence of helminth infection among our study population, rather than association with risk factors.…”

“…mansoni , reporting a high prevalence of up to 50% in well-known high-risk S . mansoni areas around Lake Victoria (North-Western part of Tanzania), where the natural open freshwater serves as a habitat for the intermediate host snails [ 34 , 35 ]. However, a recent systematic review highlighted a low specificity of the POC-CCA test assay in detecting S .…”

Population level changes in schistosome‐specific antibody levels following chemotherapy

“…Pre‐treatment infection intensity determines the quantity of schistosome parasites’ antigens that participants are exposed to following PZQ treatment. On the other hand, in endemic areas, participant age correlates with the cumulative history of exposure to schistosome parasites . A study in baboons reported that attenuated schistosome parasite vaccines were effective regardless of the different schistosome infection history (naïve or infected then PZQ‐treated) .…”