17 A Manmade Disease

名称：17 A Manmade Disease
内容简介：
新概念英语第四册（英音）
[al:新概念英语（四）]
[ar:MP3 同步字幕版（英音）]
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[00:01.55]Lesson 17
[00:03.76]A man-made disease
[00:12.84]What factor helped to spread the disease of myxomatosis?
[00:19.81]In the early days of the settlement of Australia, enterprising settlers unwisely introduced the European rabbit.
[00:28.27]This rabbit had no natural enemies in the Antipodes, so that it multiplied with that promiscuous abandon characteristic of rabbits.
[00:39.36]It overran a whole continent.
[00:41.81]It caused devastation by burrowing and by devouring the herbage which might have maintained millions of sheep and cattle.
[00:50.85]Scientists discovered that this particular variety of rabbit (and apparently no other animal) was susceptible to a fatal virus disease, myxomatosis.
[01:03.19]By infecting animals and letting them loose in the burrows, local epidemics of this disease could be created.
[01:11.15]Later it was found that there was a type of mosquito which acted as the carrier of this disease and passed it on to the rabbits.
[01:20.29]So while the rest of the world was trying to get rid of mosquitoes, Australia was encouraging this one.
[01:27.83]It effectively spread the disease all over the continent and drastically reduced the rabit population.
[01:35.04]It later became apparent that rabbits were developing a degree of resistance to this disease,
[01:41.22]so that the rabbit population was unlikely to be completely exterminated.
[01:46.90]There were hopes, however, that the problem of the rabbit would become manageable.
[01:53.12]Ironically, Europe, which had bequeathed the rabbit as a pest to Australia, acquired this man-made disease as a pestilence.
[02:02.70]A French physician decided to get rid of the wild rabbits on his own estate and introduced myxomatosis.
[02:10.22]It did not, however, remain within the confines of this estate.
[02:14.71]It spread through France, where wild rabbits are not generally regarded as a pest but as a sport and a useful food supply,
[02:23.95]and it spread to Britain where wild rabbits are regarded as a pest but where domesticated rabbits,
[02:30.93]equally susceptible to the disease, are the basis of a profitable fur industry.
[02:36.90]The question became one of whether Man could control the disease he had invented.