Zélé Flore, Vézilier Juilen, L'Ambert Gregory, Nicot Antoine, Gandon Sylvain, Rivero Ana, Duron Olivier
Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, (UMR CNRS-UM1-UM2 5290, IRD 224), Centre de Recherche IRD, 911 Avenue Agropolis, 34394 Montpellier, France.
Parasit Vectors. 2014 Sep 16;7:437. doi: 10.1186/1756-3305-7-437.
Identifying the parasites transmitted by a particular vector and the factors that render this vector susceptible to the parasite are key steps to understanding disease transmission. Although avian malaria has become a model system for the investigation of the ecological and evolutionary dynamics of Plasmodium parasites, little is still known about the field prevalence, diversity and distribution of avian Plasmodium species within the vectors, or about the extrinsic factors affecting Plasmodium population dynamics in the wild.
We examined changes in avian malaria prevalence and Plasmodium lineage composition in female Culex pipiens caught throughout one field season in 2006, across four sampling sites in southern France. Using site occupancy models, we correct the naive estimates of Plasmodium prevalence to account for PCR-based imperfect detection. To establish the importance of different factors that may bear on the prevalence and diversity of avian Plasmodium in field mosquitoes, we focus on Wolbachia and filarial parasite co-infections, as well as on the insecticide resistance status of the mosquito.
Plasmodium prevalence in Cx. pipiens increased from February (0%) to October (15.8%) and did not vary significantly among the four sampling sites. The application of site occupancy models leads to a 4% increase in this initial (naive) estimate of prevalence. The parasite community was composed of 15 different haemosporidian lineages, 13 of which belonged to the Plasmodium genus, and 2 to the Haemoproteus genus. Neither the presence of different Wolbachia types and of filarial parasites co-infecting the mosquitoes, nor their insecticide resistance status were found to affect the Plasmodium prevalence and diversity.
We found that haemosporidian parasites are common and diverse in wild-caught Cx. pipiens mosquitoes in Southern France. The prevalence of the infection in mosquitoes is unaffected by Wolbachia and filarial co-infections as well as the insecticide resistant status of the vector. These factors may thus have a negligible impact on the transmission of avian malaria. In contrast, the steady increase in prevalence from February to October indicates that the dynamics of avian malaria is driven by seasonality and supports that infected birds are the reservoir of a diverse community of lineages in southern France.
确定由特定病媒传播的寄生虫以及使该媒介易感染寄生虫的因素，是理解疾病传播的关键步骤。尽管禽疟疾已成为研究疟原虫生态和进化动态的模型系统，但对于病媒中禽疟原虫种类的野外流行率、多样性和分布，或影响野外疟原虫种群动态的外在因素，仍知之甚少。
我们研究了2006年一个野外季节期间，在法国南部四个采样点捕获的雌性致倦库蚊中禽疟疾流行率和疟原虫谱系组成的变化。使用位点占有率模型，我们对疟原虫流行率的原始估计值进行校正，以考虑基于PCR的检测不完善问题。为确定可能影响野外蚊子中禽疟原虫流行率和多样性的不同因素的重要性，我们重点关注沃尔巴克氏体和丝虫寄生虫的共感染，以及蚊子的抗药性状况。
致倦库蚊中的疟原虫流行率从2月的0%增加到10月的15.8%，且在四个采样点之间没有显著差异。位点占有率模型的应用使这一流行率的初始（原始）估计值提高了4%。寄生虫群落由15种不同的血孢子虫谱系组成，其中13种属于疟原虫属，2种属于血变原虫属。未发现不同类型的沃尔巴克氏体和丝虫寄生虫共感染蚊子，以及它们的抗药性状况会影响疟原虫的流行率和多样性。
我们发现血孢子虫寄生虫在法国南部野外捕获的致倦库蚊中很常见且种类多样。蚊子感染的流行率不受沃尔巴克氏体和丝虫共感染以及病媒抗药性状况的影响。因此，这些因素对禽疟疾传播的影响可能微乎其微。相比之下，从2月到10月流行率的稳步上升表明，禽疟疾的动态受季节性驱动，并支持感染鸟类是法国南部不同谱系群落的储存宿主这一观点。
