Botswana has a small population, about two million, but a very big HIV prevalence rate.

VOA: standard.2010.05.10

So, this just shows as the vaccine was distributed, given to more people, that prevalence of the disease dropped dramatically.

因此,这表明随着疫苗的推广,以及接种人数的增加,该疾病的患病率显著降低

耶鲁公开课 - 生物医学工程探索课程节选

As those doses were given you look at the prevalence of polio within the United States.

随着疫苗的使用,你可以看到全美小儿麻痹症

耶鲁公开课 - 生物医学工程探索课程节选

This high prevalence rate has fueled the tuberculosis epidemic.

VOA: standard.2010.05.29

Those same estimates say that if you could turn that around, that if the world could eat the recommended level of fruits and vegetables, that you'd reduce the prevalence of heart disease by 31%.

反过来说就是,如果大家都能食用适量的水果和蔬菜,那心脏病的普遍性将降低31%

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

A recent progress report on HIV/AIDS says Botswana is one of the nine Southern African countries that continue to bear the global burden of HIV/AIDS, with each country having an adult prevalence of more than 10 percent. The government's national AIDS control program has boosted testing,prevention and treatment efforts.

VOA: standard.2010.05.10

Then, also emphasizing in the case of smallpox, how even after the scientific discovery was made, it took many, many decades for people to be able to produce the vaccine in large enough quantities and distribute it, so that you could think about making an impact on global prevalence of the disease.

同时重点就天花疫苗的发展展开了讨论,而即便当科学发现了天花病毒,仍然过了许多年,人类才能够,大规模生产并使用天花疫苗,由此你们可以了解到,在全球范围内,疫苗给天花以致命一击

耶鲁公开课 - 生物医学工程探索课程节选

(OMITTED) It's still low prevalence, but you know we've just put out the synthesis report, which was an epidemiological study of HIV and its evolution in the region, and the report says that probably, at least for the near future, we'll never have an epidemic of HIV in the region.

VOA: standard.2010.07.07