title: Ivermectin efficacy against Biomphalaria, intermediate host snail vectors of Schistosomiasis.
abstract: The impact of ivermectin on adult snails of the genus Biomphalaria (B. glabrata, B. tenagophila and B. straminea), B. glabrata infected with Schistosoma mansoni, snail egg-masses cercariae and miracidia, as well as on guppy fish (Poecilia reticulata) was examined and evaluated. Biomphalaria snails, egg-masses, parasite stages and guppies were all exposed to different concentrations of ivermectin for 24 h, followed by regular observations of mortality. The calculated lethal doses of ivermectin were around an LD50of 0.03 μg ml-1, and an LD90of 0.3 μg ml-1for the three species of snails. Specimens of B. glabrata actually shedding parasite cercariae all died when exposed to ivermectin at a concentration of a mere 0.01 μg ml-1. Ivermectin B1a, the major (80%) component of commercially available ivermectin, proved to be inactive, and it was the minor (20%) component, ivermectin B1b, which caused snail death. Snail egg-masses were not affected, even at the highest concentration of 100 μg ml-1. With respect to S. mansoni parasite stages, 0.2 μg ml-1ivermectin killed 50% of cercariae and miracidia within five minutes, rising to 90% after 30 min. Mortality of guppy fish within 24 h of exposure to ivermectin at concentrations of 0.5 μg ml-1and 0.01 μg ml-1, were 100% and 30%, respectively. The concentration of 0.01 μg ml-1that killed Schistosoma mansoni-infected snails only caused 30% mortality in guppy fish. Ivermectin can be considered a promising molluscicide, especially as it is more potent against infected snails than uninfected ones, although it has no impact on egg-masses. Ivermectin and its derivatives could be explored in the search for a new agent to help control schistosomiasis transmission.
authors.affiliation: Centro de Pesquisas René Rachou/Fiocruz, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Naftale
authors.initials: N
authors.lastname: Katz
authors.affiliation: Centro de Pesquisas René Rachou/Fiocruz, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Neusa
authors.initials: N
authors.lastname: Araújo
authors.affiliation: Centro de Pesquisas René Rachou/Fiocruz, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Paulo Marcos Zech
authors.initials: PMZ
authors.lastname: Coelho
authors.affiliation: National Institute for Science and Technology on Innovation on Neglected Diseases (INCT/IDN), Center for Technological Development in Health (CDTS), Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro, RJ, Brazil.
authors.forename: Carlos Medicis
authors.initials: CM
authors.lastname: Morel
authors.affiliation: National Institute for Science and Technology on Innovation on Neglected Diseases (INCT/IDN), Center for Technological Development in Health (CDTS), Oswaldo Cruz Foundation (Fiocruz), Rio de Janeiro, RJ, Brazil.
authors.forename: Ana Rosa
authors.initials: AR
authors.lastname: Linde-Arias
authors.affiliation: Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.|Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamada
authors.affiliation: Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Horimatsu
authors.affiliation: Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Koh
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.|Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Sunazuka
authors.affiliation: Kitasato Institute for Life Sciences, Kitasato University, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ōmura
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001700:Biomphalaria / Q000469:parasitology*; D004305:Dose-Response Relationship, Drug; D007559:Ivermectin / Q000008:administration & dosage / Q000494:pharmacology*; D007928:Lethal Dose 50; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000302:isolation & purification; D012555:Schistosomiasis mansoni / Q000188:drug therapy* / Q000469:parasitology; D013997:Time Factors
chemical_list: D000977:Antiparasitic Agents; D007559:Ivermectin