Lesson 17
A man-made disease
人为的疾病
First listen and then answer the following question.
听录音，然后回答以下问题。
What factor helped to spread the disease of myxomatosis?
In the early days of the settlement of Australia, enterprising settlers unwisely introduced the European rabbit. This rabbit had no natural enemies in the Antipodes, so that it multiplied with that promiscuous abandon characteristic of rabbits. It overran a whole continent. It caused devastation by burrowing and by devouring the herbage which might have maintained millions of sheep and cattle. Scientists discovered that this particular variety of rabbit (and apparently no other animal) was susceptible to a fatal virus disease, myxomatosis. By infecting animals and letting them loose in the burrows, local epidemics of this disease could be created. 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. So while the rest of the world was trying to get rid of mosquitoes, Australia was encouraging this one. It effectively spread the disease all over the continent and drastically reduced the rabbit population. It later became apparent that rabbits were developing a degree of resistance to this disease, so that the rabbit population was unlikely to be completely exterminated. There were hopes, however, that the problem of the rabbit would become manageable.
Ironically, Europe, which had bequeathed the rabbit as a pest to Australia, acquired this man-made disease as a pestilence. A French physician decided to get rid of the wild rabbits on his own estate and introduced myxomatosis. It did not, however, remain within the confines of his estate. It spread through France, Where wild rabbits are not generally regarded as a pest but as sport and a useful food supply, and it spread to Britain where wild rabbits are regarded as a pest but where domesticated rabbits, equally susceptible to the disease, are the basis of a profitable fur industry. The question became one of whether Man could control the disease he had invented.
RITCHIE CALDER Science Makes Sense
在澳大利亚移民初期，一些有创业精神的移民不明智地把欧洲兔子引进了澳大利亚。这种兔子在澳大利亚及新西兰没有天敌，因此便以兔子所特有的杂乱交配迅猛繁殖起来。整个澳洲兔子成灾。它们在地下打洞，吃掉本可以饲养数百万头牛羊的牧草，给澳洲大陆造成了毁灭性的破坏。科学家们发现，这种特殊品种的兔子（显然不包括别的动物）易患一种叫“多发性粘液瘤”的致命毒性疾病。通过让染上此病的动物在洞内乱跑，就可以使这种疾病在一个地区蔓延起来。后来又发现，有一种蚊子是传播这种疾病的媒介，能把此病传染给兔子。因此，世界上其他地方在设法消灭蚊子的时候，澳大利亚却在促使这种蚊子大量繁殖。蚊子把这种疾病扩散到整个澳洲大陆，效果甚佳，结果兔子的数目在为减少。后来，明显看出，兔子对这种疾病已产生了一定程度的免疫力，所以兔子不可能被完全消灭。但是，已有希望解决兔子所带来的问题。 具有讽刺意味的是，欧洲把这种兔子作为有害动物传给澳洲，而欧洲自己却染上了这种人为的瘟疫般的疾病。一位法国内科医生决定除掉自己庄园内的野兔子，于是引进了这种多发性粘液瘤疾病。然而，这种疾病并未被局限在他的庄园内，结果在整个法国蔓延开来。野兔在法国一般不被当作有害动物，而被视为打猎取乐的玩物和有用的食物来源。这种疾病又蔓延到了英国。在英国，野兔被当作有害的动物，可是家兔是赚钱的毛皮工业的基础，然而家兔同样易感染这种疾病。现在的问题是，人类能否控制住这种人为的疾病。
