La protection du voyageur contre les piqûres de moustiques

Risk of malaria reemergence in southern France: testing scenarios with a multiagent simulation model

The Camargue, a region in southern France, is considered a potential site for malaria reemergence. All the suitable factors of the disease transmission system are present -- competent mosquito vectors, habitats for their breeding, and susceptible people -- except for the parasite. The objective of this study was to test potential drivers of malaria reemergence in this system after possible changes in biological attributes of vectors, agricultural practices, land use, tourism activities, and climate. Scenarios of plausible futures were formulated and then simulated using a spatially explicit and dynamic multiagent simulation: the MALCAM model. Scenarios were developed by varying the value of model inputs. Model outputs were compared based on the contact rate between people and potential malaria vectors, and the number of new infections in case of reintroduction of the parasite in the region. Model simulations showed that the risk of malaria reemergence is low in the Camargue. If the disease would reemerge, it would be the result of a combination of unfavorable conditions: introduction of a large population of infectious people or mosquitoes, combined with high levels of people-vector contacts resulting from significant changes in land use, tourism activities, agricultural policies, biological evolution of mosquitoes, and climate changes. The representation in the MALCAM model of interactions and feedbacks between different agents, and between agents and their environment, led in some cases to counterintuitive results. Results from scenario analyses can help local public health authorities in policy formulation.

Combined exposure to DEET (N,N-diethyl-m-toluamide) and permethrin: pharmacokinetics and toxicological effects

Permethrin and DEET are concurrently used for pests control inside homes, in public places, and in military shelters. Combined exposure to these compounds produced greater biochemical, behavioral, and metabolic alterations in animals compared to each individual compound. Concurrent application of DEET and permethrin induced urinary excretion of 3-nitrotyrosine and 8-hydroxy-2'-deoxyguanosine, markers of DNA damage and oxidative stress in rats, increased the release of rat brain mitochondrial cytochrome c, disrupted the blood-brain barrier (BBB) in rats, decreased m2 muscarinic acetylcholine receptor ligand binding density in rat brain, increased urinary excretion of 6 beta-hydroxycortisol, a marker CYP3A4 induction, altered sensorimotor and locomotor activities in rats, and changed in vivo and in vitro metabolism and pharmacokinetic profiles of the individual compound. These findings show that more research is needed to examine adverse effects of the combined use of DEET and permethrin on other biochemical/physiological system(s) and to predict mechanistic pathways for these effects, particularly mechanism of action at cellular and molecular levels and alterations of genes transcription.