Urogenital schistosomiasis and soiltransmitted helminthiasis(STH)in Cameroon:An epidemiological update at Barombi Mbo and Barombi Kotto crater lakes assessing prospects for intensified control interventions

Background:The crater lakes of Barombi Mbo and Barombi Kotto are well-known transmission foci of schistosomiasis and soil-transmitted helminthiasis having had several important control initiatives previously.To collect contemporary epidemiological information,a cross-sectional survey was undertaken inclusive of:signs and symptoms of disease,individual treatment histories,local water,sanitation and hygiene(WASH)-related factors and malacological surveillance,with molecular characterisation of specimens.Methods:At each lake,a community cross-sectional survey was undertaken using a combination of stool and urine parasitological sampling,and interview with pro-forma questionnaires.A total of 338 children and adults participated.Material from snail and parasite species were characterised by DNA methods.Results:Egg-patent prevalence of urogenital schistosomiasis was 8.7%at Barombi Mbo(all light-intensity infections)and 40.1%at Barombi Kotto(21.2%heavy-intensity infections).Intestinal schistosomiasis was absent.At Barombi Kotto,significantly more women reported signs and symptoms associated with female genital schistosomiasis.While there had been extensive recent improvement in WASH-related infrastructure at Barombi Mbo,water contact risk scores were higher among schistosomiasis-infected participants(P<0.001)and at Barombi Kotto in general(P<0.001).Across both lakes,mean prevalence of STH was very low(6.3%)evidencing an impressive decrease of 79.0%over the last decade;neither Strongyloides stercoralis nor Ascaris lumbricoides were found.A total of 29 freshwater sampling sites were inspected for snails,13 in Barombi Mbo and 16 in Barombi Kotto;water chemistry differed significantly(P<0.0001)between lakes for both mean pH(7.9 v.9.6)and mean conductivity(64.3μS v.202.1μS)respectively.Only two Bulinus camerunensis found on the central island of Barombi Kotto were observed to shed schistosome cercariae,but schistosome DNA was later detected in Bulinus sampled from both lakes as well as in Indoplanorbis exustus,an invasive species from Asia.Conclusions:STH is currently at very low levels while urogenital schistosomiasis is of greatest concern at Barombi Kotto.This assessment highlights a unique opportunity for further study of the epidemiological dynamics at these crater lakes,to evaluate future intensified interventions both in terms of gaining and sustaining control at Barombi Kotto or in moving towards local interruption of transmission of both diseases at Barombi Mbo.

Reinfection of urogenital schistosomiasis in pre-school children in a highly endemic district in Northern Zimbabwe:a 12 months compliance study

Background:In light of the shift to aiming for schistosomiasis elimination,the following are needed:data on reinfection patterns,participation,and sample submission adherence of all high-risk age groups to intervention strategies.This study was conducted to assess prevalence,reinfections along with consecutive participation,sample submission adherence,and effect of treatment on schistosomiasis prevalence in children aged five years and below in an endemic district in Zimbabwe,over one year.Methods:The study was conducted from February 2016-February 2017 in Madziwa area,Shamva district.Following community mobilisation,mothers brought their children aged 5 years and below for recruitment at baseline and also urine sample collection at baseline,3,6,9 and 12 months follow up surveys.At each time point,urine was tested for urogenital schistosomiasis by urine filtration and children found positive received treatment.Schistosoma haematobium prevalence,reinfections as well as children participation,and urine sample submission at each visit were assessed at each time point for one year.Results:Of the 535 children recruited from the five communities,169(31.6%)participated consecutively at all survey points.The highest mean number of samples submitted was 2.9 among communities and survey points.S.haematobium prevalence significantly reduced from 13.3%at baseline to 2.8%at 12 months for all participants and from 24.9%at baseline to 1.8%at 12 months(P<0.001)for participants coming at all-time points.Among the communities,the highest baseline prevalence was found in Chihuri for both the participants coming consecutively(38.5%,10/26)and all participants(20.4%,21/103).Reinfections were significantly high at 9 months follow up survey(P=0.021)and in Mupfure(P=0.003).New infections significantly decreased over time(P<0.001).Logistic regression analysis showed that the risk of acquiring schistosomiasis was high in some communities(P<0.05).Conclusions:S.haematobium infections and reinfections are seasonal and depend on micro-geographical settings.The risk of being infected with schistosomes in pre-school aged children increases with increasing age.Sustained treatment of infected individuals in a community reduces prevalence overtime.Participation compliance at consecutive visits and sample submission adherence are important for effective operational control interventions.