Institut Pasteur du Maroc, Laboratoire des Maladies Vectorielles, Casablanca, Maroc.
PLoS One. 2012;7(5):e36757. doi: 10.1371/journal.pone.0036757. Epub 2012 May 31.
West Nile fever (WNF) and Rift Valley fever (RVF) are emerging diseases causing epidemics outside their natural range of distribution. West Nile virus (WNV) circulates widely and harmlessly in the old world among birds as amplifying hosts, and horses and humans as accidental dead-end hosts. Rift Valley fever virus (RVFV) re-emerges periodically in Africa causing massive outbreaks. In the Maghreb, eco-climatic and entomologic conditions are favourable for WNV and RVFV emergence. Both viruses are transmitted by mosquitoes belonging to the Culex pipiens complex. We evaluated the ability of different populations of Cx. pipiens from North Africa to transmit WNV and the avirulent RVFV Clone 13 strain. Mosquitoes collected in Algeria, Morocco, and Tunisia during the summer 2010 were experimentally infected with WNV and RVFV Clone 13 strain at titers of 10(7.8) and 10(8.5) plaque forming units/mL, respectively. Disseminated infection and transmission rates were estimated 14-21 days following the exposure to the infectious blood-meal. We show that 14 days after exposure to WNV, all mosquito st developed a high disseminated infection and were able to excrete infectious saliva. However, only 69.2% of mosquito strains developed a disseminated infection with RVFV Clone 13 strain, and among them, 77.8% were able to deliver virus through saliva. Thus, Cx. pipiens from the Maghreb are efficient experimental vectors to transmit WNV and to a lesser extent, RVFV Clone 13 strain. The epidemiologic importance of our findings should be considered in the light of other parameters related to mosquito ecology and biology.
西尼罗河热（WNF）和裂谷热（RVF）是正在出现的疾病，它们在其自然分布范围之外引发了流行。西尼罗河病毒（WNV）在旧世界的鸟类中广泛而无害地循环，鸟类是扩增宿主，马和人类是偶然的末端宿主。裂谷热病毒（RVFV）在非洲周期性重新出现，导致大规模爆发。在马格里布，生态气候和昆虫学条件有利于 WNV 和 RVFV 的出现。这两种病毒都是由属于库蚊复合体的蚊子传播的。我们评估了来自北非的不同种群的库蚊传播 WNV 和弱毒 RVFV Clone 13 株的能力。2010 年夏季在阿尔及利亚、摩洛哥和突尼斯收集的蚊子，用 WNV 和 RVFV Clone 13 株在 10（7.8）和 10（8.5）蚀斑形成单位/ml 的滴度进行了实验感染。在接触传染性血餐 14-21 天后，估计了传播感染和传播率。我们表明，在接触 WNV 14 天后，所有蚊子都发展出高度传播感染，并能够排出传染性唾液。然而，只有 69.2%的蚊株对 RVFV Clone 13 株产生传播感染，其中 77.8%能够通过唾液传递病毒。因此，马格里布的库蚊是高效的实验传播媒介，可以传播 WNV，并且在较小程度上可以传播 RVFV Clone 13 株。考虑到与蚊子生态学和生物学相关的其他参数，我们的发现具有重要的流行病学意义。
