title: Distribution and abundance of schistosomiasis and fascioliasis host snails along the Mara River in Kenya and Tanzania.
abstract: We purposively selected 39 sampling sites along the Mara River and its two perennial tributaries of Amala and Nyangores and sampled snails. In addition, water physicochemical parameters (temperature, turbidity, dissolved oxygen, conductivity, alkalinity, salinity and pH) were taken to establish their influence on the snail abundance and habitat preference. Out of the 39 sites sampled, 10 (25.6%) had snails. The snail species encountered included Biomphalaria pfeifferi Krauss - the intermediate host of Schistosoma mansoni Sambon, Bulinus africanus - the intermediate host of Schistosoma haematobium, and Lymnaea natalensis Krauss - the intermediate host of both Fasciola gigantica and F. hepatica Cobbold. Ceratophallus spp., a non-vector snail was also encountered. Most (61.0%) of the snails were encountered in streamside pools. Schistosomiasis-transmitting host snails, B. pfeifferi and B. africanus, were fewer than fascioliasis-transmitting Lymnaea species. All the four different snail species were found to be attached to different aquatic weeds, with B. pfeifferi accounting for over half (61.1%) of the snails attached to the sedge, followed by B. africanus and Lymnaea spp., accounting for 22.2 and 16.7%, respectively. Ceratophallus spp. were non-existent in sedge. The results from this preliminary study show that snails intermediate hosts of schistosomiasis and fascioliasis exists in different habitats, in few areas along the Mara River, though their densities are still low to have any noticeable impacts on disease transmission in case they are infected. The mere presence of the vector snails in these focal regions calls for their immediate control and institution of proper regulations, management, and education among the locals that can help curtail the spread of the snails and also schistosomiasis and fascioliasis within the Mara River basin.
authors.affiliation: School of Public Health and Community Development, Maseno University, Maseno, Kenya ; Department of Vector Ecology and Environment, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.
authors.forename: Gabriel O
authors.initials: GO
authors.lastname: Dida
authors.affiliation: Probe International, Inc., Copley, OH, USA ; Probe International, Inc., Auckland, New Zealand.
authors.forename: Frank B
authors.initials: FB
authors.lastname: Gelder
authors.affiliation: School of Environment and Earth Science, Maseno University, Maseno, Kenya.
authors.forename: Douglas N
authors.initials: DN
authors.lastname: Anyona
authors.affiliation: School of Environment and Earth Science, Maseno University, Maseno, Kenya ; EAC-Lake Victoria Basin Commission Secretariat, Kisumu, Kenya.
authors.forename: Ally-Said
authors.initials: AS
authors.lastname: Matano
authors.affiliation: School of Environment and Earth Science, Maseno University, Maseno, Kenya.
authors.forename: Paul O
authors.initials: PO
authors.lastname: Abuom
authors.affiliation: School of Public Health and Community Development, Maseno University, Maseno, Kenya.
authors.forename: Samson O
authors.initials: SO
authors.lastname: Adoka
authors.affiliation: School of Public Health and Community Development, Maseno University, Maseno, Kenya.
authors.forename: Collins
authors.initials: C
authors.lastname: Ouma
authors.affiliation: EAC-Lake Victoria Basin Commission Secretariat, Kisumu, Kenya.
authors.forename: Canisius K
authors.initials: CK
authors.lastname: Kanangire
authors.affiliation: Department of Chemistry, Maseno University, Maseno, Kenya.
authors.forename: Phillip O
authors.initials: PO
authors.lastname: Owuor
authors.affiliation: School of Public Health and Community Development, Maseno University, Maseno, Kenya.
authors.forename: Ayub V O
authors.initials: AV
authors.lastname: Ofulla
keywords: Fascioliasis; Habitat preference; Mara River; Schistosomiasis; Vector snails