How do viruses mutate and jump species? And why are 'spillovers' becoming more common?

viruses will “emerge” or “spillover” from their original host to a new host. Image credit: Shutterstock[/caption]According to the BBC, conservation experts think COVID-19 could also threaten animals such as wild gorillas, chimps and orangutans.While virologists are intensely interested in how viruses mutate and transmit between species – and understand this process to an extent – many gaps in knowledge remain.

Skilled in their craft

Most viruses are specialists. They establish long associations with preferred host species. In these relationships, the virus may not induce disease symptoms. In fact, the virus and host may benefit each other in symbiosis.Occasionally, viruses will “emerge” or “spillover” from their original host to a new host. When this happens, the risk of disease increases. Most infectious diseases that affect humans and our food supply are the result of spillovers from wild organisms.The new coronavirus (SARS-CoV-2) that emerged from Wuhan in November isn’t actually “new”. The virus evolved over a long period, probably millions of years, in other species where it still exists. We know the virus has close relatives in Chinese rufous horseshoe bats, intermediate horseshoe bats, and pangolins - which are considered a delicacy in China.Past coronaviruses, including the severe acute respiratory syndrome coronavirus (SARS-CoV), have jumped from bats to humans via an intermediary mammal. Some experts propose Malayan pangolins provided SARS-CoV-2 this link.Although the original host of the SARS-CoV-2 virus hasn’t been identified, we needn’t be surprised if the creature appears perfectly healthy. Many other coronaviruses exist naturally in wild mammal and bird populations around the world.

Where do they keep coming from?

Smuggled pangolins are killed for their scales to be used in traditional Chinese medicine. They are suspected to be the world’s most-trafficked mammal, apart from humans. Image credit: Shutterstock[/caption]

How do they make the jump?

Let wildlife be wildlife

Despite how many viruses exist, relatively few threaten us, and the plants and animals we rely on.Nonetheless, some creatures are especially dangerous on this front. For instance, coronaviruses, Ebola and Marburg viruses, Hendra and Nipah viruses, rabies-like lyssaviruses, and mumps/measles-like paramyxoviruses all originate from bats.Given the enormous number of viruses that exist, and our willingness to provide them global transport, future spillovers are inevitable. We can reduce the chances of this by practising better virus surveillance in hospitals and on farms.We should also recognise wildlife, not only for its intrinsic value, but as a potential source of disease-causing viruses. So let’s maintain a “social distance” and leave wildlife in the wild.Steve Wylie, Adjunct Associate Professor, Murdoch UniversityThis article is republished from The Conversation under a Creative Commons license. Read the original article.