TUESDAY, April 6, 2021 (HealthDay News) -- Because of the COVID-19 pandemic, scientists thought twice about studying North American bats in their winter habitats. But they've now determined that the risk of humans passing the coronavirus to bats under these conditions was low.
The U.S. Geological Survey (USGS) led the study. It found the risk to be one in 1,000 with no protective measures and one in 3,333 with proper use of personal protective equipment or if scientists test negative for COVID-19 before beginning research.
"This is a small number, but the consequences of human-to-bat transmission of coronavirus are potentially large," said USGS scientist Evan Grant, an author of the new rapid risk assessment.
"The virus has not been identified in North American bats, but if it is introduced, it could lead to illness and mortality, which may imperil long-term bat conservation. It could also represent a source for new exposure and infection in humans," Grant explained in a USGS news release.
The origin of SARS-CoV-2 is not confirmed, but studies indicate the virus likely originated from similar viruses found in bats in Asia.
So, there are "hard risks for wildlife managers and other decision makers to weigh as they consider whether and how to allow researchers to study bats in their winter colonies," Grant said.
The new research specifically looked at the potential transmission of SARS-CoV-2 (the virus that causes COVID-19) from people to bats.
The USGS and U.S. Fish and Wildlife Service considered three bat species in the analysis: free-tailed bats; little brown bats; and big brown bats. They were chosen because they have physical and behavioral differences and are typical of the kinds of bats studied in winter.
The study focused on the winter season, when some wildlife scientists conduct field work that may require close contact with or direct handling of the animals. This includes research on white-nose syndrome, a disease that has killed millions of bats in North America, and population studies that support Endangered Species Act decisions.
According to USGS scientist Michael Runge, another author of the new assessment, "If scientists wear protective equipment, particularly properly fitted masks with high filtration efficiency, or test negative for COVID-19 before conducting the research, they greatly reduce the risk of transmission to North American bats."
There are still many unknowns about how susceptible North American bats are to SARS-CoV-2 and how future virus variants may affect transmission, Grant said.
Jeremy Coleman, national white-nose syndrome coordinator for the fish and wildlife service, was also an author of the report. He said, "The potential for SARS-CoV-2 to infect wildlife is a real concern for state and federal wildlife management agencies and reflects the important connections between human health and healthy environments. Natural resource managers need information from these kinds of analyses to make science-based decisions that advance conservation efforts while also protecting the health of people, bats and other wildlife."
This research builds on a USGS-led study published last year that examined the likelihood of researchers transmitting the coronavirus to bats during summer research.
Bats have an erroneously bad reputation as menacing creatures at Halloween and in horror movies, but they provide important natural services. USGS studies have found that bats save the U.S. agriculture industry more than $3 billion per year by eating pests that damage crops, reducing the need for pesticides.
Authors of the new study did not examine potential transmission of the coronavirus from bats to people.
The findings were published online recently in Conservation Science and Practice.
The North American Society for Bat Research has more information on bat conservation.
SOURCE: U.S. Geological Survey, news release, April 1, 2021