Tony Goldberg knows that most human diseases, like COVID-19, don’t start – or end – with our species. These diseases are really part of our entire ecosystem, and that includes the animals we interact with.
Goldberg and his lab at the University of Wisconsin-Madison School of Veterinary Medicine are disease sleuths who study viruses in all their movements and mutations, including in nonhuman animals. They are checking North American bats for SARS-CoV-2, because if bats were to acquire the virus, they could serve to reinfect human populations, lengthening the pandemic.
But they also study how humans endanger wildlife by transmitting our viruses to the animals we come into contact with.
Only by looking at the big picture will scientists like Goldberg uncover the full history of viruses on Earth.
Animals as reservoirs
“We knew SARS-CoV-2 came from animals,” Goldberg says. “And the best bet is that it comes from bats (in China).” So Goldberg and his colleagues began searching the American Southwest for bats that could serve as a reservoir for the virus, transmitting it and possibly infecting humans again in the future.
These bats migrate from South America to New Mexico and other parts of the southwestern United States. The team chose this area for their study because of the diversity of bats in many of these places, including bats that live alongside people in homes, under bridges and in other places. parts of the built environment.
Goldberg and collaborators Kathy Hanley and Teri Orr, both faculty members at New Mexico State University, received a grant to study whether bats carry SARS-CoV-2 or viruses similar. The process has three steps. They first humanely trap the bats, take swab samples from them, and then immediately release them into the wild. Back at the lab, they test the samples for any traces of the virus.
Although the team is still conducting research, they have yet to detect COVID-19 in bats in the southwestern United States, Goldberg said. Other organizations, like the National Wildlife Health Center and the US Department of Agriculture, are also investigating.
If bats haven’t caught SARS-CoV-2 yet, that’s a good sign, Goldberg says, because wildlife reservoirs can make virus control more difficult. But even if the team doesn’t spot the COVID-19 virus, their research could pay off in finding what else might be infecting these bats.
“Everything has a virus (that can infect it),” says Goldberg. “The methods we use are very broad…so we will find something. The question is, does it matter? Does it matter to bats, and does it matter to people? »
“There are papers published every day about new crazy-sounding viruses and all kinds of animals from all over the world,” he adds. “And very, very, very few of them become a problem for human health.”
A surprising reservoir of SARS-CoV-2 is wild deer in the United States, and Goldberg’s colleagues across the country have been racing to figure out whether infected deer can transmit the virus to people who come into contact with them.
Findings published in the journal Nature by researchers at Ohio State University found that deer have contracted the virus multiple times from people and are spreading it among themselves. Although transmission from deer to humans has not been conclusively demonstrated, early results suggest it may be happening. Such studies demonstrate a serious need for monitoring deer, the environment, and other hosts on a global scale.
“Given how quickly it has spread in deer, the fact that they don’t appear to be symptomatic – and the fact that researchers have found it in the lymph nodes of deer, which generally indicates a virus that has power — it’s probably not going away anytime soon,” Goldberg told Discover magazine in November.
A human threat
But the threat of species-hopping viruses goes both ways. As people encroach on wildlife habitat, we bring our diseases with us.
Goldberg witnessed this harsh truth at his long-term field site in Uganda. Since 2005, he and many national and international partners have studied how human-caused changes to ecosystems in and around Kibale National Park threaten chimpanzees and gorillas with human respiratory disease.
For example, previous research from Goldberg’s Kibale EcoHealth project found the first case of rhinovirus C in non-humans. Although the virus only causes colds in humans, it killed 10% of chimpanzees at a study site in Uganda in 2013.
Goldberg’s team also documented metapneumovirus and human respirovirus 3, two human-caused respiratory diseases, in wild chimpanzees from the same forest in 2017. In humans, the viruses cause common croup in infants. age and mortality rates are extremely low. For chimpanzees, the health consequences are much more serious.
In Uganda, Goldberg and her partners are also working together to guide and implement changes to reduce disease transmission from humans to chimpanzees.
“People go into the forest and transmit these viruses to the monkeys,” Goldberg says. “He can kill monkeys even though he doesn’t cause us much trouble. … The idea that viruses can move in either direction – from people to animals or from animals to people – is important to understand.