VOA慢速英语:Seeking a Better Way for African Farmers to Fight a Fever

East Coast fever kills hundreds of thousands of cattle in eastern and central Africa every year. The animals become infected when they get bitten by ticks carrying the parasite that causes the disease. A parasite is an organism that feeds on other organisms.
非洲东部和中部地区每年有数万头牛死于“东海岸热”。当动物携带了能够引起该疾病的寄生虫的蜱虫叮咬后就会被感染。寄生虫是一种以其它生物为食的生物。

Donald Knowles directs the animal disease research unit in the Agricultural Research Service, part of the United States Department of Agriculture. The service is working with the International Livestock Research Institute in Kenya to find better ways to prevent parasitic diseases in cattle. Dr. Knowles is also a professor at Washington State University.
Donald Knowles管理美国农业部下属的农业研究服务中心的疾病科研部门。该部门与肯尼亚国际牲畜研究所合作，寻找更的好办法，来防止牛类寄生虫病。Knowles博士也是在美国华盛顿州立大学的教授。

He points out that East Coast fever is not a contagious disease, so animals cannot give it to each other.
他指出，东海岸热不是一种传染性疾病，所以动物间不会互相传染。

DONALD KNOWLES: "You need a tick to transmit from one infected cow to the other. They won’t transmit just by standing next to each other. You need a tick to move it between them."
DONALD KNOWLES：“被感染的牛传染需要靠蜱虫来传染给其他的妞。他们不会因为站在一起而互相传染，需要蜱虫在他们中间传播。”

Farmers in parts of Africa use a vaccination method against East Coast fever known as infect and treat. First they infect animals with live parasites. Then they treat them with drugs to help them recover.
非洲部分地区的农民使用一种所谓的先感染后治疗的疫苗接种方法来对抗东海岸热。他首先，他们用活寄生虫感染的动物。然后，他们用药物治疗，以帮助他们恢复。

That way, explains Dr. Knowles, the animal becomes immunized or vaccinated against a full case of the deadly fever. But there are problems with this method of vaccination. Uninfected ticks that bite the vaccinated animal can still get infected and spread the parasite to other animals.
这样一来，诺尔斯博士解释，动物对各类致命发热都具备免疫力。但这种疫苗接种方法也有问题。未受感染的蜱虫叮咬接种过的动物后仍然会被感染，然后通过寄生虫传播给其他动物。

DONALD KNOWLES: "Once a cow is infected with this parasite, all the data indicates that the cow stays infected for life. And the consequences of that, the big deal about that is, that means that cow, even a cow that has been vaccinated, now it’s protected against the disease, but it can still transmit. See it’s infected for life. And so that animal is still a source of transmission."
DONALD KNOWLES：“所有数据表明，一旦一头牛被这种寄生虫感染，这头牛会终生保持被感染状态。这样的结果意味着一个大问题是，这头牛即使是接种过疫苗，能够抵抗这种疾病，但它仍然会传播疾病，它终生被感染。所以该动物仍然是一个传染源。”

And that is not the only problem with this method of vaccination.
而这并不是使用这种疫苗接种方法的唯一问题。

DONALD KNOWLES: "One of the things in using live vaccines is that they usually require cold storage. And that adds to the cost of it, and also adds to the difficulty of using it in places like Africa."
DONALD KNOWLES：“使用活性疫苗的问题之一就是，它们往往需要冷藏。这增加了疫苗的成本，增加了在像非洲这样的地方使用它的难度。”

For more than four years, American and Kenyan scientists have studied diseases carried by ticks. The scientists in the United States centered their work on the parasite that causes Texas cattle fever. This fever is common to the Americas.
四年多来，美国和肯尼亚的科学家们研究由蜱携带的疾病。美国科学家将工作重点放到了引起德克萨斯州牛发烧的寄生虫上。这种发烧在美洲很常见。

This year, the scientists began a new study in Africa. The study is aimed at developing a new vaccine for the East Coast fever parasite. Dr. Knowles says their goal is a vaccine that does not require infecting and treating animals or the need for cold storage.
今年以来，科学家们在非洲开始一个新的研究。这项研究的目的是开发一个新的东海岸热寄生虫疫苗。Knowles博士称，他们的目标是开发一种不需要先感染后治疗的疫苗，或不需要冷藏的疫苗。