Epidemiology Of Urogenital Schistosomiasis, Snail Intermediate Hosts, And Awareness Among Primary School Children In Endemic Areas Of Ethiopia

Abstract

Background: Urogenital schistosomiasis (UGS) is a neglected tropical disease caused by Schistosoma haematobium and it is one of the public health problems in Ethiopia.Freshwater Bulinus snails are intermediate hosts for the parasite transmission.The disease is prevalent in some parts of Ethiopia such as Afar, Gambella, Benishangul Gumuz and Somalia Regions. The aim of this study is to determine the prevalence and intensity of UGS, to evaluate diagnostic performance of urinalysis reagent strip, to determine potential intermediate host snails for the transmission of UGS, to determine human water contact behavior and physico chemical characteristics of Alwero reservoir, and to assess the KAPs of schoolchildren towards urogenital schistosomasis Methods: A cross-sectional study was conducted among primary schoolchildren. A total of 1,171 study participants aged 5-15 years were selected randomly. A total of 1,171 urine samples were collected from schoolchildren and examined with the urine filtration method and urinalysis reagent strip. A study was also conducted through questionnaire to assess KAP on urogenital schistosomiasis among primary schoolchildren. Bulinus snails were sampled from each of the 12 snail sampling sites at Alwero reservoir using metal scoop net. Bulinus snail were counted and identified according to shell morphology. The snail samples were then examined for natural schistosome infections by shedding method. Moreover, a total of 206 study participants were interviewed to determine human water contact activities. The water temperature, pH, total dissolved solid (TDS), salinity and conductivity of the dam reservoir in each site were measured using Tracer pocketester. Dissolved oxygen of the water was determined using HQ40d multimeter. Data were analysed using Microsoft Excel 2007 and SPSS (version.20). Results: Of the 1,171 urine samples collected from school children examined by urine filtration method, 143 (12.2%) were positive for Schistosma haematobium egg. Out of 143 positive children, 126 (88.1%) had light infection intensity and 17 (11.9%) had heavy intensity. Among the total of 1,171 urine samples tested by urinalysis reagent strip, 264 (22.5%) were positive for haematuria. The number of egg counts were significantly correlated with level of haematuria (r = 0.6, P ˂ 0.001). Compared to urine filtration method, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of urinalysis reagent strip were 99.3%, 88.1%, 53.8% and 99.8%, respectively. Positive likelihood ratio (PLR) and negative likelihood ratio (NLR) was 8.34 and 0.008, respectively.The agreement level between urine filtration methods and urinalysis xi reagent strip for detecting UGS was substantial (Kappa = 0.64). A total of 1,125 fresh water Bulinus snails were collected from 12 surveyed sites. Of these, 72 (6.4%) were infected with echinostome cercariae but none of the samples were found infected with schistosome cercariae. The abundance of Bulinus snails was significantly higher in stony substratum compared to sandy substratum habitat type (P = 0.01). Of the total 206 participants, 119 (57.8%) had water contact activity which included washing clothes and bathing. Majority of the respondents 144 (70.0%) reported that they visited the dam reservoir one or two times a week, while 16.5% and 13.6% reported that they visited the reservoir three to five times a week and every day, respectively. Similarly, 149 (72.3%) respondents had a history of urogenital schistosomiasis. The mean water temperature, pH, dissolved oxygen, total dissolved solid, electric conductivity and salinity of the dam water was 28.6°C, 7.07, 5.75 mg/L, 90.0 ppm, 124.8 µS/cm and 50.0 ppm, respectively. Of the 1,171 interviewed schoolchildren, 654(55.8%) claimed to have heard of UGS. Of the total respondents, 13.9% used river/dam water as main household water source and 28.9% of them had a history of urogenital schistosomiasis infection.