Schistosoma mansoni infection among preschool children in southern Ethiopia: burden, treatment, community behavior, and association with undernutrition and anaemia

Abstract

Introduction: Intestinal schistosomiasis presents a significant health threat, predominantly in sub Saharan Africa including Ethiopia. Preschool children (pre-SAC) are omitted from preventive chemotherapy (PC) intervention aimed at accelerating the control and elimination of this threat due to scarce evidence on the burden of the disease, its effect, and the efficacy and safety of praziquantel (PZQ) in this population group. Despite the growing spread of schistosomiasis among pre-SAC, evidence is insufficient on the knowledge, attitude, and practices (KAP) of caregivers in communities with limited access to safe drinking water and basic sanitation. Objective: The overall objective of this PhD work was to determine the extent and risk factors of S. mansoni infection among pre-SAC, to investigate the efficacy and safety of PZQ in the treatment of the disease, to assess the KAP about schistosomiasis among caregivers of pre-SAC, and to investigate the association of the disease with undernutrition and anaemia among pre-SAC in Hawella Tulla district of Sidama region, Southern Ethiopia from August to December 2021. Methods: A mix of study designs was used based on the different objectives of this dissertation. A community-based cross-sectional study was conducted for papers (I, III, and IV). A single-arm before-and-after quasi-experimental study was carried out among pre-SAC infected with S. mansoni for the second paper. A multistage sampling technique was applied and the study participants were selected by a simple random sampling technique (papers I, III, and IV). All S. mansoni-nfected participants were recruited (paper II). A multilevel logistic regression model was used to investigate the determinants of S. mansoni infection (paper I). The determinants of cure rate were assessed using a standard logistic regression model, while a log-binomial regression model was used to investigate the predictors of adverse events (AEs) following praziquantel treatment (paper II). Further, multivariable logistic regression with a cluster-robust variance estimation method was used to assess determinants of KAP (paper III); and the association between S. mansoni infection and undernutrition and anaemia (paper IV). A total of 1683 randomly selected children aged 4 to 7 years were involved in a baseline survey to establish baseline data (paper I). A structured questionnaire was used to interview mothers/ primary caregivers to obtain sociodemographic and behavioral information. Two duplicate thick slides were prepared from a single fresh stool sample and tested for S. mansoni on the same day using the Kato-Katz technique for each study participant. Efficacy and safety assessment of a single-dose 40 mg/kg PZQ was done among 240 S. mansoni-infected pre-SAC. Follow-up was carried out at day 28 post-treatment among 236 pre-SAC for efficacy, while safety monitoring was done among 234 pre-SAC at day 1, 2, and eight post-PZQ administration. KAP about schistosomiasis was assessed among 887 mothers/primary caregivers of pre-SAC. Anthropometric measurements and blood samples for haemoglobin were taken from 565 pre-SAC to investigate the association of S. mansoni infection with undernutrition and anaemia. Results: The findings of this study indicated a moderate (14.3%) prevalence of the disease among pre-SAC in the study setting. Being 6-year-old and 7-year-old had increased odds of S. mansoni infection. Accompanying others to water sources sometimes or all the time, and living within less than one-kilometer radius of the infested water source also had a significant association with S. mansoni infection. The present study detected that PZQ is effective and safe against the disease given at 40 mg/kg body weight in this population segment. In general, the egg reduction rate (ERR) was 93.3% while the cure rate (CR) was 85.2% at day 28 after treatment. A significant association was detected between baseline infection intensity and CRs. A baseline S. mansoni egg count per gram of stool (EPG) increase in 100 had reduced the odds of cure by 26%. The occurrence of AEs was 23.1% with stomachache being the most common. Pre-treatment moderate or heavy-intensity infection was a significant risk factor for AEs. A low level of good knowledge (37.0%) about schistosomiasis was detected among caregivers of pre-SAC. Only 486 (54.8%) caregivers had favorable attitude about schistosomiasis, while over half (57.8%) of mothers/primary caregivers had good practice related to predisposing factors of schistosomiasis. Being from the poorest and poorer household wealth categories had reduced odds of reporting good knowledge relative to those from the richest wealth households. Besides, study participants' age, not having formal education, and household wealth were significant determinants of attitude. Marital status and lack of information about the disease were significant determinants of practice. Overall, of the total 565 pre-SAC examined, 24.3% were stunted, 6.6% were wasted, 2.0% were underweight whereas 28.0% had anaemia. Pre-SAC having S. mansoni with soil-transmitted helminths (STH) co-infection had significantly higher odds of stunting relative to those infected only with S. mansoni. Besides, S. mansoni infection had an independent significant association with anaemia, but not stunting, wasting, or underweight. Conclusion: The study detected a moderate prevalence of the disease among pre-SAC. In S. mansoni-infected pre-SAC, a single-dose 40 mg/kg PZQ is safe and effective, and most treatment associated AEs detected were mild-to-moderate and transient. The current study detected a low level of knowledge, an unfavorable attitude, and poor practice about schistosomiasis. Further, S. mansoni with STH co-infection had higher odds of stunting, whereas S. mansoni infection had anindependent association with anaemia among the infected pre-SAC. Thus, these findings call for policymakers and other stakeholders to consider the inclusion of pre-SAC in schistosomiasis control and elimination programs to enhance the elimination efforts of the disease in endemic communities.