title: Urogenital schistosomiasis and soil-transmitted helminthiasis (STH) in Cameroon: An epidemiological update at Barombi Mbo and Barombi Kotto crater lakes assessing prospects for intensified control interventions.
abstract: 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 (64.3 μS v. 202.1 μS) 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.
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Suzy J
authors.initials: SJ
authors.lastname: Campbell
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. russell.stothard@lstmed.ac.uk.
authors.forename: J Russell
authors.initials: JR
authors.lastname: Stothard
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Faye
authors.initials: F
authors.lastname: O'Halloran
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Deborah
authors.initials: D
authors.lastname: Sankey
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Timothy
authors.initials: T
authors.lastname: Durant
authors.affiliation: Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon.
authors.forename: Dieudonné Eloundou
authors.initials: DE
authors.lastname: Ombede
authors.affiliation: Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon.
authors.forename: Gwladys Djomkam
authors.initials: GD
authors.lastname: Chuinteu
authors.affiliation: Department of Life Sciences, Parasites and Vectors Division, Natural History Museum, London, SW7 5BD, UK.|London Centre for Neglected Tropical Disease Research, London, UK.
authors.forename: Bonnie L
authors.initials: BL
authors.lastname: Webster
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: Lucas
authors.initials: L
authors.lastname: Cunningham
authors.affiliation: Department of Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
authors.forename: E James
authors.initials: EJ
authors.lastname: LaCourse
authors.affiliation: Centre for Schistosomiasis and Parasitology, Yaoundé, Cameroon.|Laboratory of Parasitology and Ecology, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon.|National Programme for the Control of Schistosomiasis and Intestinal Helminthiasis, Ministry of Public Health, Yaoundé, Cameroon.
authors.forename: Louis-Albert
authors.initials: LA
authors.lastname: Tchuem-Tchuenté
mesh_terms: D000818:Animals; D002033:Bulinus / Q000469:parasitology; D002163:Cameroon / Q000453:epidemiology; D003430:Cross-Sectional Studies; D006801:Humans; D015995:Prevalence; D012553:Schistosomiasis haematobia / Q000453:epidemiology* / Q000469:parasitology / Q000517:prevention & control*; D012987:Soil / Q000469:parasitology
chemical_list: D012987:Soil
keywords: Bulinus; Female genital schistosomiasis; Indoplanorbis exustus; Schistosoma haematobium; Strongyloides; WASH