Common Host-Derived Chemicals Increase Catches of Disease-Transmitting Mosquitoes and Can Improve Early Warning Systems for Rift Valley Fever Virus

Rift Valley fever (RVF), a mosquito-borne zoonosis, is a major public health and veterinary problem in sub-Saharan Africa. Surveillance to monitor mosquito populations during the inter-epidemic period (IEP) and viral activity in these vectors is critical to informing public health decisions for early warning and control of the disease. Using a combination of field bioassays, electrophysiological and chemical analyses we demonstrated that skin-derived aldehydes (heptanal, octanal, nonanal, decanal) common to RVF virus (RVFV) hosts including sheep, cow, donkey, goat and human serve as potent attractants for RVFV mosquito vectors. Furthermore, a blend formulated from the four aldehydes and combined with CO2-baited CDC trap without a light bulb doubled to tripled trap captures compared to control traps baited with CO2 alone. Our results reveal that (a) because of the commonality of the host chemical signature required for attraction, the host-vector interaction appears to favor the mosquito vector allowing it to find and opportunistically feed on a wide range of mammalian hosts of the disease, and (b) the sensitivity, specificity and superiority of this trapping system offers the potential for its wider use in surveillance programs for RVFV mosquito vectors especially during the IEP.裂谷热（Rift Valley fever, RVF）是一种经蚊媒传播的人兽共患病，在撒哈拉以南非洲地区构成严峻的公共卫生与兽医卫生问题。在流行间期（inter-epidemic period, IEP）对蚊种群进行监测，并检测这些媒介生物中的病毒活性，可为该疾病的早期预警与防控决策提供关键依据。本研究结合野外生物测定、电生理与化学分析方法，证实裂谷热病毒（Rift Valley fever virus, RVFV）宿主（涵盖绵羊、牛、驴、山羊及人类）共有的皮肤源醛类物质（庚醛（heptanal）、辛醛（octanal）、壬醛（nonanal）、癸醛（decanal）），可作为RVFV媒介蚊的强效引诱剂。此外，由上述四种醛类配制的诱剂组合，搭配无光源的二氧化碳诱饵CDC诱捕器（CDC trap），其诱捕蚊量相较于仅以二氧化碳为诱饵的对照诱捕器提升至2至3倍。本研究结果表明：其一，由于引诱所需的宿主化学信号具有共通性，宿主与媒介的互作似乎更利于媒介蚊，使其能够定位并机会性吸食该疾病的多种哺乳动物宿主；其二，该诱捕系统的灵敏度、特异度与性能优势，使其具备在RVFV媒介蚊监测项目中推广应用的潜力，尤其适用于流行间期的监测工作。