title: Reduction of infectivity of schistosome cercariae by application of cercaricidal oil to water.
abstract: Schistosomiasis continues to plague populations living in disease-endemic areas, and exposure to infective cercariae results in more than 200 million cases worldwide. Laboratory experiments were conducted to test whether a cercaricidal film applied directly to the water surface can reduce viability of cercariae. A distillate from inexpensive cedarwood oil enriched for cedrol in a mixed oil fraction was formulated (1:5) with the surfactant Tween 80. When applied to the surface of clean and turbid water in test vessels, the formulation spread across and just below the air-water interface, causing inactivation of Schistosoma mansoni cercariae within minutes. The active ingredient was heat stable and reduced schistosome survival and infectivity by 90% and 99.2%, respectively in a mouse model. The effective dose (13 mug/cm(2)) was dependent on surface area rather than volume of water treated. We conclude that application of the biodegradable formulation to the surface of schistosome-infested waters may be an effective, economical, and safe means of reducing human infections.
authors.affiliation: Department of Molecular Microbiology and Immunology, and Department of Environmental Health Sciences, Center for Water and Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA. jnaples@jhsph.edu
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: Naples
authors.forename: Clive
authors.initials: C
authors.lastname: Shiff
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
mesh_terms: D000818:Animals; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D009822:Oils, Volatile / Q000737:chemistry / Q000494:pharmacology*; D011136:Polysorbates / Q000737:chemistry / Q000494:pharmacology; D012550:Schistosoma mansoni / Q000187:drug effects / Q000254:growth & development* / Q000472:pathogenicity*; D012555:Schistosomiasis mansoni / Q000188:drug therapy / Q000469:parasitology*; D014867:Water / Q000737:chemistry / Q000469:parasitology*
chemical_list: D009822:Oils, Volatile; D011136:Polysorbates; D014867:Water; C042023:cedarwood oil