History is repeating itself: Probable zoonotic spillover as the cause of the 2019 novel coronavirus epidemic

Pathogen transmission from a vertebrate animal to a human, also known as zoonotic spillover, represents a global public health burden, which while associated with multiple outbreaks, still remains a poorly understood phenomenon. Coronaviruses, like influenza viruses, circulate in nature in various animal species. Alpha-coronaviruses and beta-coronaviruses can infect mammals and gamma-coronaviruses and delta-coronaviruses tend to infect birds, but some of them can also be transmitted to mammals. Although still preliminary, current data suggest that bats are the most probable initial source of the current 2019 novel CoV (2019nCoV) outbreak, that begun on December 2019 in Wuhan, China, apparently spreading from a "wet market" to multiple cities and provinces in China. This epidemic of 2019nCoV, already reaching more than 6,000 cases to-day (end of January 2020) (>90% in China), will not be the last one linked to zoonotic spillover events.