它们都具有很高的传染性；并且可以使人体产生各种症状，从而确保其传染性的传播。

They are highly contagious; the virus causes the body to produce symptoms which ensure the spread of the contagion.

youdao

目前一项新的研究发现大多数孩子对传染性打哈欠不敏感，直到他们4岁左右——而且患自闭症的孩子也比其他孩子不太可能受哈欠传染。

Now a new study has found that most children aren't susceptible to contagious yawning until they're about 4 years old — and that children with autism are less likely to yawn contagiously than others.

youdao

存在蚊子唾液里面的病毒是具有传染性的，而那些存在蚊子肠道里面的病毒是无法传染的。

Viruses in mosquito saliva can be transmitted, but those in the gut cannot infect a new host when a mosquito bites.

youdao

And one of the reasons that's most responsible for that is that humans aren't dying at as young an age from infectious diseases as they did three or four hundred years ago.

最重要的一个原因就是,人们不会在年轻的时候死于传染性疾病,而这在三四百年前确实会发生

耶鲁公开课 - 生物医学工程探索课程节选

It worked for them, they didn't have all these chronic diseases like we have, now they had other challenges, infectious diseases primarily, but they didn't have the chronic diseases like we have, like cancer, heart disease, hypertension, hyperlipidaemia, etc., and Diabetes particularly.

这曾对祖先们奏效,他们不像我们会得一些慢性疾病,但他们要面对其他的挑战,主要是传染性疾病,但他们不像我们那样受着慢性疾病的困扰,如癌症,心脏病,高血压和高脂血等,特别是糖尿病

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选