Ответ:
Although many animals carry dangerous viruses, they are usually not transmitted to humans - to our happiness.
"In most cases, there is a species barrier that the virus cannot overcome," says Professor Andrew Easton of the School of Biomedical Sciences at Vorik University.
Image copyrightREUTERS
Image caption
Doctors treating victims of current outbreak in China are taking harsh precautions
But sometimes, if a person has an immunodeficiency or there is some other important factor that will open the virus to the body, it is possible to get an uncharacteristic sporadic case (infection. - Ed.), "- says the scientist.
The danger often begins with an unusual mutation.
"There will usually be some changes that will allow him to grow into a new host," Professor Easton explains.In these rare cases, when the coronavirus is transmitted to humans, the situation can be very serious.
Coronavirus: How a Wuhan woman "cheated" at an airport check
It is worth noting that not all coronaviruses are very dangerous - people are constantly faced with less harmful types. But it is precisely those that are transmitted from one species to another that pose the greatest danger.
Подробнее - на Znanija.com - znanija.com/task/34957861#readmore