Paludisme : perspectives des recherches en entomologie médicale à Madagascar

Les études entomologiques du paludisme à Madagascar avaient surtout concerné le comportement des vecteurs vis-à-vis des insecticides. L'arrêt des pulvérisations intradomiciliaires et l'absence de chloroquine ont permis la recrudescence de la maladie sur les plateaux dans les années 80. Ce phénomène a fait ressortir l'hétérogénéité de la transmission dans l'île. Il a été nécessaire de définir les caractéristiques entomologiques des quatre principaux faciès de transmission malgaches. Ces enquêtes ont permis de fournir aux services de Santé publique les bases épidémiologiques pour organiser les mesures de lutte et de prévention. Dans le paysage très anthropisé des plateaux, la nature des vecteurs, leur densité et leur compétence vectorielle présentent de grandes variations locales. Les études entomologiques cherchent à préciser les différents facteurs humains et environnementaux qui modulent la transmission et constituent des facteurs de risque épidémique. Cette approche microépidémiologique facilitera l'analyse et la comparaison des résultats cliniques et biologiques obtenus dans les différents foyers. La recherche en entomologie médicale permettra également de proposer des schémas de lutte adaptés aux différentes situations. (Résumé d'auteur

Assessment of vector/host contact: comparison of animal-baited traps and UV-light/suction trap for collecting Culicoides biting midges (Diptera: Ceratopogonidae), vectors of Orbiviruses

<p>Abstract</p> <p>Background</p> <p>The emergence and massive spread of bluetongue in Western Europe during 2006-2008 had disastrous consequences for sheep and cattle production and confirmed the ability of Palaearctic <it>Culicoides </it>(Diptera: Ceratopogonidae) to transmit the virus. Some aspects of <it>Culicoides </it>ecology, especially host-seeking and feeding behaviors, remain insufficiently described due to the difficulty of collecting them directly on a bait animal, the most reliable method to evaluate biting rates.</p> <p>Our aim was to compare typical animal-baited traps (drop trap and direct aspiration) to both a new sticky cover trap and a UV-light/suction trap (the most commonly used method to collect <it>Culicoides</it>).</p> <p>Methods/results</p> <p>Collections were made from 1.45 hours before sunset to 1.45 hours after sunset in June/July 2009 at an experimental sheep farm (INRA, Nouzilly, Western France), with 3 replicates of a 4 sites × 4 traps randomized Latin square using one sheep per site. Collected <it>Culicoides </it>individuals were sorted morphologically to species, sex and physiological stages for females. Sibling species were identified using a molecular assay. A total of 534 <it>Culicoides </it>belonging to 17 species was collected. Abundance was maximal in the drop trap (232 females and 4 males from 10 species) whereas the diversity was the highest in the UV-light/suction trap (136 females and 5 males from 15 species). Significant between-trap differences abundance and parity rates were observed.</p> <p>Conclusions</p> <p>Only the direct aspiration collected exclusively host-seeking females, despite a concern that human manipulation may influence estimation of the biting rate. The sticky cover trap assessed accurately the biting rate of abundant species even if it might act as an interception trap. The drop trap collected the highest abundance of <it>Culicoides </it>and may have caught individuals not attracted by sheep but by its structure. Finally, abundances obtained using the UV-light/suction trap did not estimate accurately <it>Culicoides </it>biting rate.</p

Implementation of surveillance of invasive mosquitoes in Belgium according to the ECDC guidelines

BACKGROUND: In 2012, the new guidelines for the surveillance of IMS in Europe, produced by the European Centre for Disease Prevention and Control (ECDC), were tested in Belgium. This study aimed at (1) testing the usefulness and applicability in the field of the ECDC guidelines for the surveillance of IMS in Europe and (2) surveying IMS throughout Belgium. METHODS: First, the scenarios, which Belgium is facing, were identified according to the ECDC guidelines. Second, the surveillance strategy and the methods were identified based on the guidelines and adjusted to the Belgium context. Two areas colonised by IMS and 20 potential points of entry (PoE) were selected. Mosquito Magnet Liberty Plus (CO(2)-baited) traps (23) and oviposition traps (147) were set-up, and larval sampling was performed monthly or bi-monthly from July till October 2012. Finally, the costs and workload of the surveillance activities were compared to the estimates provided by the ECDC guidelines. RESULTS: Surveillance at 20 potential PoE (complying with scenario 1) revealed that no new IMS were established in Belgium. Surveillance at two sites colonised by IMS (scenario 2) indicated that although control measures have drastically reduced the Ae. j. japonicus population this species is still present. Furthermore, Ae. koreicus is permanently established. For both scenarios, the problems encountered are discussed and recommendations are given. In addition, the actual workload was lower than the estimated workload, while the actual costs were higher than the estimated ones. CONCLUSIONS: The ECDC guidelines are helpful, applicable and efficient to implement surveillance of IMS in Belgium. Recommendations were customised to the local context (political demands, salary and investment costs, and existing expertise). The workload and costs related to the preparatory phase (i.e., planning, contacts with the PoE, writing a protocol) were found to be missing in the cost evaluation suggested in the guidelines. Updates on the occurrence of IMS in Belgium and the related risk for disease agents they can transmit will only be available once a structured and permanent surveillance system is implemented

Molecular Identification of Palaearctic <em>Culicoides</em> Blood Meals from Different Localities in France

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Paludisme : perspectives des recherches en entomologie médicale à Madagascar

Les études entomologiques du paludisme à Madagascar avaient surtout concerné le comportement des vecteurs vis-à-vis des insecticides. L'arrêt des pulvérisations intradomiciliaires et l'absence de chloroquine ont permis la recrudescence de la maladie sur les plateaux dans les années 80. Ce phénomène a fait ressortir l'hétérogénéité de la transmission dans l'île. Il a été nécessaire de définir les caractéristiques entomologiques des quatre principaux faciès de transmission malgaches. Ces enquêtes ont permis de fournir aux services de Santé publique les bases épidémiologiques pour organiser les mesures de lutte et de prévention. Dans le paysage très anthropisé des plateaux, la nature des vecteurs, leur densité et leur compétence vectorielle présentent de grandes variations locales. Les études entomologiques cherchent à préciser les différents facteurs humains et environnementaux qui modulent la transmission et constituent des facteurs de risque épidémique. Cette approche microépidémiologique facilitera l'analyse et la comparaison des résultats cliniques et biologiques obtenus dans les différents foyers. La recherche en entomologie médicale permettra également de proposer des schémas de lutte adaptés aux différentes situations. (Résumé d'auteur

Host preferences of Palaearctic Culicoides biting midges: implications for transmission of orbiviruses

International audienceFeeding success depends on host availability, host defensive reactions and host preferences. Host choice is a critical determinant of the intensity at which pathogens are transmitted. The aim of the current study was to describe host preferences of Palaearctic Culicoides species (Diptera: Ceratopogonidae) Latreille using traps baited with the five different host species of poultry, horse, cattle, sheep and goat. Collections were carried out nightly in July and August 2009 in western France with three replicates of a 5 x 5 randomized Latin square (five sites, five hosts). Moreover, an ultraviolet (UV) light/suction trap was operated during host-baited collections to correlate Culicoides biting rates and UV light/suction trap catches. A total of 660 Culicoides belonging to 12 species, but comprised mainly of Culicoides scoticus Downes and Kettle, Culicoides dewulfi Goetghebuer and Culicoides obsoletus Meigen, were collected on animal baits. Abundance was highest for the horse, which accounted for 95% of all Culicoides caught, representing 10 species. The horse, the largest bait, was the most attractive host, even when abundance data were corrected by weight, body surface or Kleiber's scaling factor. Culicoides obsoletus was the only dominant species attracted by birds. Both C. scoticus and C. dewulfi were collected mainly from the upper body of the horse. Finally, the quantification of host preferences allows for discussion of implications for the transmission of Culicoides-borne pathogens such as bluetongue virus