title: The effects of subcurative doses of chloroquine on Plasmodium vinckei petteri gametocytes and on their infectivity to mosquitoes.
abstract: The effects of subcurative doses of chloroquine on rodent and human Plasmodium transmission to the mosquito have been studied by several authors who showed a short-term (12 h) enhancement of gametocyte infectivity by the drug, restricted to chloroquine-resistant strains, and a long term (4-6 days) enhancement of gametocytogenesis of chloroquine-sensitive strains of Plasmodium chabaudi. We investigated both short- and long-term effects of chloroquine on Plasmodium vinckei petteri, a chloroquine-sensitive rodent Plasmodium strain. Chloroquine treatment reduced the index of gametocytogenesis to 73% (5 mg/kg) and 55% (2.5 mg/kg) of controls, on day 6 post-infection (p.i.). The reduction was statistically significant with 5 mg/kg chloroquine. However, the reduction of gametocyte numbers did not affect the transmission capabilities of the strain. Our experiments showed that doses of 1 mg/kg chloroquine had no effect on the oocyst counts, 12 h post-administration to mice. A statistically non-significant 61% reduction of oocyst numbers was observed in mosquitoes fed on mice treated with 5 mg/kg chloroquine. The effect of 5 mg/kg chloroquine administration on the infectivity of gametocytes to mosquitoes fed 1 h post-treatment was also investigated. An overall 41% reduction of oocyst numbers was observed. This immediate effect was statistically significant in 73% of the mice. These results are consistent with the hypothesis that the short-term enhancing effect of chloroquine on transmission is restricted to the drug-resistant strains of Plasmodium.
authors.affiliation: Laboratoire de Parasitologie et de Mycologie Médicale, Pavillon Camille Guérin, CHU la Miletrie, BP 577, 86021 Poitiers Cedex, France. parasitologie@chu-poitiers.fr
authors.forename: P
authors.initials: P
authors.lastname: Gautret
authors.forename: I
authors.initials: I
authors.lastname: Landau
authors.forename: L
authors.initials: L
authors.lastname: Tailhardat
authors.forename: F
authors.initials: F
authors.lastname: Miltgen
authors.forename: F
authors.initials: F
authors.lastname: Coquelin
authors.forename: T
authors.initials: T
authors.lastname: Voza
authors.forename: A G
authors.initials: AG
authors.lastname: Chabaud
authors.forename: J L
authors.initials: JL
authors.lastname: Jacquemin
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D000871:Anthelmintics / Q000008:administration & dosage / Q000494:pharmacology*; D002738:Chloroquine / Q000008:administration & dosage / Q000494:pharmacology*; D004351:Drug Resistance; D008288:Malaria / Q000188:drug therapy*; D008297:Male; D051379:Mice; D018512:Parasitemia; D010961:Plasmodium / Q000187:drug effects*; D018709:Statistics, Nonparametric
chemical_list: D000871:Anthelmintics; D002738:Chloroquine