THE new coronavirus is the latest example of a disease that jumped from animals into humans. When infections do this they can be deadly – and 2019-nCoV is no exception.

Nearly all viruses and bacteria that infect other organisms are completely harmless to people. But a tiny proportion can infect us and cause so-called zoonotic diseases, which come from animals rather than other people.

“Zoonotic diseases can be so deadly because we have no pre-existing immunity to them”