[30]Epidemiology.

感谢收听,期待你对本期节目的评论留言哦～ 2017.2.25 Economist Science and Technology Epidemiology [ˌepɪˌdi:miˈɒlədʒi]流行病学 Snap! [snæp]猛地咬住 Boston How to use mosquitoes[məsˈki:təuz]蚊子 to combat [ˈkɒmbæt]与…斗争 disease. Imagine a small drone[drəʊn]无人机 that could fly around sampling animals and people in an effort to see which pathogens['pæθədʒəns]病菌 are present in an area, and what host species harbour them.That would be invaluable非常宝贵的 to epidemiologists seeking to understand how diseases spread, and how to predict and pre-empt[priˈempt] 先发制人their outbreaks爆发. At the moment, such a drone is beyond human technology. But this may not matter, because nature has already come up with one. It is called the mosquito. Mosquitoes (female mosquitoes, at any rate) draw blood from animals to feed on. While doing so, they also ingest[ɪnˈdʒest]咽下 any bloodborn pathogens present in those animals.What a splendid[ˈsplendɪd] 极好的 idea, thought Ethan Jackson and Jonathan Carlson, of Microsoft Research in Seattle, to design a system that captures mosquitoes so that the pathogens they have ingested can be studied. Thus, as Dr Jackson explained to the AAASmeeting,was Project Premonition[ˌpri:məˈnɪʃn]预警 born. The core of the project is a portable[ˈpɔ:təbl]手提的; 轻便的;mosquito trap夹子. The current version 版本 of this is a cylinder[ˈsɪlɪndə(r)] 圆柱体 about 35cm high, with 64 cells the size of matchboxes火柴盒 arranged around its exterior [ɪkˈstɪəriə(r)]表面. Each of these cells has a door that springs shut in a tenth十分之一的 of a second in response to the breaking of an infrared[ˌɪnfrəˈred] beam红外线 that is shining invisibly inside it. The spring is made from a shape-memory alloy[ˈælɔɪ]合金—a material that, when bent into a new configuration [kənˌfɪgəˈreɪʃn]形状, remains in this new shape until an electric current电流 is run through it. Then it suddenly reverts to恢复 the old shape. Mosquitoes are lured[ lʊə（r ）] 吸引to the cells by puffs烟 of carbon dioxide (which mimic[ˈmɪmɪk]模仿 an animal’s exhalations[ˌekshə'leɪʃn]发散物), or skin odours[ˈəudəz]气味 or ultraviolet[ˌʌltrəˈvaɪələt]紫外线的 light. If they enter a cell, they break the beam and spring the trap. One crucial piece of design is that the traps can be tuned调整 to catch mosquitoes of a single, target species. Different species carry different pathogens, so a study of certain diseases may well want to trap a particular sort of mosquito. Each mosquito species has a characteristic特有的 wing-beat frequency and the beam-detector inside a cell is sensitive enough to distinguish between these. It closes only when a member of the desired species flies inside. Once a trap has done its job, it is picked up and taken to a laboratory where the collected insects are extracted[ɪks'træktɪd]取出, mashed[mæʃ]捣碎 up and analysed metagenomically ['metə.dʒi:'nəʊmɪkli]宏基因组. Metagenomics is a technique whereby通过 the DNA in a sample containing material from several species is extracted and sequenced[ˈsi:kwəns]使按顺序排列 without first being sorted in any way. All species present thus contribute to the results, which are then matched against a database of known sequences, to see what is there. In this way, Dr Jackson and Dr Carlson are able to confirm the species of mosquito captured (for, despite the clever electronics电器, the traps do occasionally make mistakes), and also the hosts it has fed on and any pathogens it has picked up. Even if an exact match is not possible for a particular piece of DNA (not all species are in the database), the system can make an educated guess about the genus or family it came from. Sometimes, the absence of a matching sequence will be because geneticists [dʒəˈnetɪsɪst] 遗传学家 have not got around to sampling that particular species. Sometimes, though (particularly with abundant, tiny things like viruses), it will be because the species is previously unknown to science. It should therefore be possible to discover new potential pathogens in this way. Dr Jackson and Dr Carlson have tested the system successfully in Grenada[ɡrəˈneidə]格林纳达 and in Houston, Texas, and are now refining精炼 it. One hoped-for refinement改良品 is to produce traps light enough to be carried, deployed施展 and collected by actual, human-built drones. This will make it possible to deploy them in trackless无足迹的 forested areas. These are often home to wild animals that act as reservoirs[ˈrezəvwɑ:(r)]储藏 for pathogens like Ebola virus, which are mainly animal infections but sometimes break out to become epidemic [ˌepɪˈdemɪk] in people. Indeed, an important point about Project Premonition is that it is not restricted to tracking pathogens which are actually spread by mosquito but can also follow those, like Ebola, which are not. All that is required is for a pathogen to be in the host’s bloodstream血流. Mosquito trapping thus promises to become an important tool in the monitoring and prevention of infectious disease.