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 collec...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.展开更多
Background:Intestinal schistosomiasis is of public health importance in Uganda but communities living above 1400 m are not targeted for control as natural transmission is thought unlikely.To assess altitudinal boundar...Background:Intestinal schistosomiasis is of public health importance in Uganda but communities living above 1400 m are not targeted for control as natural transmission is thought unlikely.To assess altitudinal boundaries and at-risk populations,conjoint malacological and epidemiological surveys were undertaken on Mount Elgon(1139 m-3937 m),in Fort Portal crater lakes and in the Rwenzori Mountains(1123 m-4050 m).Methods:Seventy freshwater habitats[Mount Elgon(37),Fort Portal crater lakes(23),Rwenzori Mountains(8)and Lake Albert(2)]were inspected for Biomphalaria species.Water temperature,pH and conductivity were recorded.A parasitological examination of 756 schoolchildren[Mount Elgon(300),Fort Portal crater lakes(456)]by faecal microscopy of duplicate Kato-Katz smears from two consecutive stool samples was bolstered by antigen(urine-CCA dipstick)and antibody(SEA-ELISA)diagnostic assays.Results:Biomphalaria spp.was found up to 1951 m on Mount Elgon and 1567 m in the Fort Portal crater lakes.Although no snail from Mount Elgon shed cercariae,molecular analysis judged 7.1%of snails sampled at altitudes above 1400 m as having DNA of Schistosoma mansoni;in Fort Portal crater lakes three snails shed schistosome cercariae.Prevalence of intestinal schistosomiasis as measured in schoolchildren by Kato-Katz(Mount Elgon=5.3%v.Fort Portal crater lakes=10.7%),CCA urine-dipsticks(18.3%v.34.4%)and SEA-ELISA(42.3%v.63.7%)showed negative associations with increasing altitude with some evidence of infection up to 2000 m.Conclusions:Contrary to expectations,these surveys clearly show that natural transmission of intestinal schistosomiasis occurs above 1400 m,possibly extending up to 2000 m.Using spatial epidemiological predictions,this now places some extra six million people at-risk,denoting an expansion of preventive chemotherapy needs in Uganda.展开更多
基金funded as part of the COUNTDOWN research programme consortium,by the Research and Evidence Division of the Department for International Development,UK
文摘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.
基金Members of LSTM within the COUNTDOWN consortium received funding from the Research and Evidence DivisionDepartment for International Development,UK.MCS is directly funded by the Medical Research Council,UK。
文摘Background:Intestinal schistosomiasis is of public health importance in Uganda but communities living above 1400 m are not targeted for control as natural transmission is thought unlikely.To assess altitudinal boundaries and at-risk populations,conjoint malacological and epidemiological surveys were undertaken on Mount Elgon(1139 m-3937 m),in Fort Portal crater lakes and in the Rwenzori Mountains(1123 m-4050 m).Methods:Seventy freshwater habitats[Mount Elgon(37),Fort Portal crater lakes(23),Rwenzori Mountains(8)and Lake Albert(2)]were inspected for Biomphalaria species.Water temperature,pH and conductivity were recorded.A parasitological examination of 756 schoolchildren[Mount Elgon(300),Fort Portal crater lakes(456)]by faecal microscopy of duplicate Kato-Katz smears from two consecutive stool samples was bolstered by antigen(urine-CCA dipstick)and antibody(SEA-ELISA)diagnostic assays.Results:Biomphalaria spp.was found up to 1951 m on Mount Elgon and 1567 m in the Fort Portal crater lakes.Although no snail from Mount Elgon shed cercariae,molecular analysis judged 7.1%of snails sampled at altitudes above 1400 m as having DNA of Schistosoma mansoni;in Fort Portal crater lakes three snails shed schistosome cercariae.Prevalence of intestinal schistosomiasis as measured in schoolchildren by Kato-Katz(Mount Elgon=5.3%v.Fort Portal crater lakes=10.7%),CCA urine-dipsticks(18.3%v.34.4%)and SEA-ELISA(42.3%v.63.7%)showed negative associations with increasing altitude with some evidence of infection up to 2000 m.Conclusions:Contrary to expectations,these surveys clearly show that natural transmission of intestinal schistosomiasis occurs above 1400 m,possibly extending up to 2000 m.Using spatial epidemiological predictions,this now places some extra six million people at-risk,denoting an expansion of preventive chemotherapy needs in Uganda.
