Some of the deadliest diseases to infect humans have come from pathogens that jumped from animals to people.

感染人类的一些最致命的疾病来自于从动物传染给人类的病原体。

The virus that causes AIDS, for example, came from chimpanzees.

例如，导致艾滋病的病毒来自黑猩猩。

And many experts believe the virus that caused the COVID-19 pandemic came from bats.

许多专家认为，导致新冠肺炎大流行的病毒来自蝙蝠。

But, as a new study shows, this disease exchange has not been just from animals to humans.

但是，正如一项新的研究表明的那样，这种疾病的传播不仅仅是从动物到人类。

In fact, research of all the publicly available viral genome sequences produced a surprising result: humans give about two times as many viruses to animals than they give to us.

事实上，对所有可公开获得的病毒基因组序列的研究产生了一个令人惊讶的结果：人类给动物带来的病毒大约是他们给我们的两倍。

The researchers looked at nearly 12 million virus genomes and found almost 3,000 times a virus jumped from one species to another.

研究人员查看了近1200万个病毒基因组，发现病毒从一个物种跳到另一个物种近3000次。

Of those, 79 percent involved a virus going from one animal species to another animal species.

其中，79%的病毒从一个动物物种传播到另一个动物物种。

The remaining 21 percent involved humans.

剩下的21%涉及人类。

Of those, 64 percent were human-to-animal transmissions.

其中64%是人与动物之间的传播。

Thirty-six percent were animal-to-human transmissions.

36%是动物传人。

Scientists call the human-to animal transmission anthroponosis.

科学家称这种人传动物的疾病为人类疫病。

Animal-to-human transmission is called zoonosis.

动物传人被称为人畜共患病。

The animals affected by anthroponosis included pets like cats and dogs; domesticated animals like pigs, horses and cattle; birds such as chickens and ducks; primates such as chimpanzees, gorillas and howler monkeys; and other wild animals like raccoons and the African soft-furred mouse.

受人类疫病影响的动物包括猫和狗等宠物；猪、马和牛等家养动物；鸡和鸭子等鸟类；黑猩猩、大猩猩和咆哮猴等灵长类动物 以及浣熊和非洲软毛鼠等其他野生动物。

Wild animals were more likely to experience human-to-animal transmission than the other way around.

野生动物更有可能面临人类病的传染，反之亦然。

The study represents humans' large "impact on the environment and the animals around us," said Cedric Tan.

塞德里克·谭说，这项研究代表了人类对环境和我们周围动物的巨大影响。

He is a doctoral student in biology at the University College London Genetics Institute.

塞德里克·谭是伦敦大学学院遗传学研究所生物学专业的博士生。

He was a lead writer of the study, which appeared recently in the publication Nature Ecology & Evolution.

这项研究最近发表在《自然生态与进化》杂志上，而他是这篇研究的主编。

People and animals carry many microbes that can jump to another species through close contact.

人和动物携带着许多微生物，这些微生物可以通过近距离接触跳到另一个物种上。

The study looked at viral transmissions involving all the vertebrate groups: mammals, birds, reptiles, amphibians and fish.

这项研究着眼于所有脊椎动物群体的病毒传播：哺乳动物、鸟类、爬行动物、两栖动物和鱼类。

Viruses go between species in the same ways viruses are transmitted between humans, Tan said.

塞德里克谈到，病毒在物种之间传播的方式与病毒在人类之间传播的方式相同。

That includes "direct contact with infected fluids, or getting bitten by other species, amongst others."

这包括“直接接触受感染的液体，或被其他物种叮咬，等等。”

But before the virus enters a different species, it must either have "the biological toolkit, or acquire host-specific adaptations, to enter the cells of the new host species and exploit their resources," Tan added.

但在病毒进入另一个物种之前，它必须拥有“生物工具包，或获得宿主特有的适应性，以进入新宿主物种的细胞并利用其资源，”Tan补充道。

Over thousands of years, pandemics that have killed millions of people have been caused by pathogens like viruses, bacteria and fungi that crossed over to people from animals.

几千年来，已导致数百万人死亡的大流行是由病毒、细菌和真菌等病原体引起的，这些病原体从动物传播到人类身上。

Francois Balloux is director of the University College London Genetics Institute and one of the study's co-writers.

弗朗索瓦·巴卢克斯是伦敦大学学院遗传学研究所所长，也是该研究的合著者之一。

He said a large majority of pathogens in humans came from animals at some point in time.

他说，人类中的绝大多数病原体在某个时间点上来自动物。

"The current biggest threat is probably bird flu H5N1, which is circulating in wild birds," he said.

他说：“目前最大的威胁可能是在野生鸟类中传播的H5N1禽流感。”

The main reason recent pathogen jumps can be so harmful is because the "population of host species has no pre-existing immunity" to the new disease, he added.

他补充说，最近病原体的跳跃之所以如此有害，主要是因为“宿主物种群体对这种新疾病没有原有的免疫力”。

In the 14th century, the bacterial disease bubonic plague killed millions of people in Europe, Asia, the Middle East and North Africa.

在14世纪，细菌性疾病黑死病夺去了欧洲、亚洲、中东和北非数百万人的生命。

It was caused by a bacteria normally found in wild rodents.

它是由一种通常在野生啮齿动物中发现的细菌引起的。

And present-day diseases like the Ebola virus similarly came from animals.

而像埃博拉病毒这样的现代疾病也同样来自动物。

Most species-to-species transmissions are of little threat, Balloux added.

卢巴克补充说，大多数物种之间的传播威胁很小。

"In most cases, such infections lead nowhere, as the virus is poorly adapted and there is no onward transmission in the new host," he said.

他说：“在大多数情况下，这种感染不会带来任何结果，因为病毒适应能力很差，而且在新宿主中不会进一步传播。”

I'm Dan Novak.

我是丹 · 诺瓦克。