More animal-to-human virus jumps loom on the horizon

The coronavirus pandemic rages on. Unfortunately, so do the conspiracy theories. Some people say it was a planned release by a Chinese research lab in Wuhan; some say Bill Gates is using the virus to vaccinate everyone in the world; and others say the virus spread as result of the new 5G wireless networks.

What we do know is that the virus came from bats, and other wild animal species may have helped to spread the virus to humans. “Wet” markets in China are on the list of early sites that likely initiated the jump to humans.

A new study in science journal Nature suggests that expansion of urban areas and cities or even the creation of farms and ranch lands from natural or wild areas are likely major factors in a virus’ jump to humans. Land development displaces wild animals and favors animals that are adapted to urban life, like rats, mice and birds. These urban-adapted animals can carry and spread infectious diseases to people. So, when people modify the land to suit their needs, they set off a host of environmental changes that result in a higher risk of viral and bacterial disease.

When a human gets sick from an infectious microbe that spread to them from an animal, we call it a zoonosis. This jump from animals to humans occurs quite often and is the source of many of our deadliest diseases — plague, influenza, coronavirus and others. The emergence of COVID-19 has once again reminded everyone how zoonoses contribute to the toll of human disease.

Scientists think there are at least 100,000 viruses in animals waiting to make that jump into the human population. We will solve COVID-19, but there will be many to come — 3 out of every 4 new human diseases come from animals.

Why does this occur and are there things we can do to control zoonosis?

Previously, we thought that animal-to-human transfers happened when humans went into wild lands like jungles and forests. This new report suggests the conversion of wild lands to farms or cities is the greatest threat. This is based on the analysis of almost 200 previous studies, which included approximately 7,000 animal species.

When wild lands lose their native animal populations, the native animals are replaced by urban-adapted animals like rodents, birds and bats. The study shows these urban-adapted species carry more potentially dangerous microbes than animals in their native environments.

So, how do we control this? Controlling land use would help, although with our expanding population, it’s probably not practical to limit building. Much more practical would be a robust public health system to strengthen disease surveillance.

We’ve heard these ideas from our experts before, including during this latest pandemic. We would’ve been better prepared to halt or slow COVID-19 with earlier and better testing. Perhaps, we’ve learned a hard lesson and will take steps to be ready in the future. We shall see.