Opinion, Berkeley Blogs

To prevent pandemic, probe viruses that jump from animals to humans

By Wayne Getz


A photo of a fruit bat with it's wings around a tree

Whether we reside in Asia, the U.S., Europe or elsewhere, we humans are part of a biological ecosystem constantly under attack from infectious and mysterious agents. Today, public enemy No. 1 is the coronavirus COVID-19, which has been linked to bats in Wuhan, China. In just a few months, it has spread to over 70 countries, killing over 3,100 people and sickening more than 92,000.

Tomorrow we could be hit with a strain coming from an entirely different species, but one just as pernicious. To stem current and future outbreaks of wildlife-linked viruses, the United States and China must join forces to investigate host-virus systems from an ecological perspective. Together, we possess the research and development resources needed to ward off potential pandemics, and must act now.

First, we need to identify the full family of viruses that spread swiftly to humans from mammals, birds and other species. We must also learn how the distribution and density of host species might change in an ecologically disrupted and globally warming world with a burgeoning human population.

Note that humans typically do not transmit a coronavirus-causing common cold or other respiratory disease to cats, dogs, budgerigars or other pets. But every so often, along comes a species of virus that crosses over to humans from some surprising species of bird or mammal, including raccoons, bats, rats and cats, and our immune systems are caught off guard.

The three best-documented cases of coronavirus crossovers are the SARS-CoV (severe acute respiratory syndrome coronavirus) outbreak of 2003, the MERS-CoV (Middle East respiratory syndrome coronavirus) outbreak a decade ago, and the ongoing COVID-19 outbreak.

SARS-CoV first broke out in humans in Guangdong Province, China, at the end of 2002 and, in May 2003, was isolated from masked palm civets being sold in a Guangdong food market. This virus was later found in raccoons, ferrets and even domestic cats.

MERS-CoV was first identified in humans in Saudi Arabia in April 2012. This virus appears to have originated in an African bat, but it is also known to infect dromedary camels. The current COVID-19 outbreak is closely related to strains of the coronavirus found in bats, although the proximate species may even be a snake or beaver.

Along with the loss of human lives, epidemic and pandemic outbreaks are accompanied by vast economic costs to local and global economies. The West African Ebola viral disease outbreak in 2014 is estimated to have caused over 11,000 deaths and reduced the gross domestic product of the countries involved by more than 10%.

A full pandemic outbreak that impacts the whole world, rather than just a sliver of the African continent, can significantly reduce the GDP of the world itself: the Spanish influenza pandemic after World War I is estimated to have reduced worldwide GDP by 5%, a reduction of about $4 trillion.

What should we spend to prevent such losses? The National Academy of Medicines 2016 Commission on Global Health Risk Framework for the Future suggests $4.5 billion per year, or just over 0.1% of such GDP losses. But is this enough, and what should we spend it on?

If we follow the dictum that prevention is better than cure, we should be spending a significant proportion of such funds on enhancing our understanding of host-virus systems from an ecological systems perspective.

The U.S. and China are responsible for 60% to 70% of the worlds research into the ecology of infectious disease. Most importantly, however, when it comes to wildlife trade, China exports nearly 60% of all wildlife while the U.S. imports over 60%.

Given our key roles and responsibilities in this crisis, and what is at stake, it behooves the U.S. and China to significantly increase investment in the ecological systems research needed to prevent zoonotic disease pandemics instead of mobilizing only after outbreaks are detected and thousands of lives have been lost.

This commentary originally appeared in the San Francisco Chronicle's Open Forum