- The spread of the virus SARS-CoV-2, which causes COVID-19, is caused by direct transmission of this virus between humans and by contact with contaminated surfaces. Although there is some evidence suggesting that SARS-CoV-2 can be passed from humans to nonhuman animals, as well as between nonhuman animals, there is no evidence so far that animals can spread SARS-CoV-2 to humans.
- The nonhuman animal origin of SARS-CoV-2 has not been determined with certainty, but the virus is most similar to coronaviruses that occur naturally in Asian horseshoe bats and pangolins. There is no evidence that North American bats, or any bat species, currently play a role in the spread of SARS-CoV-2.
- Experts have raised the possibility that SARS-CoV-2 could spread to North American bats from humans who work closely with them. Although the risk is low, spread of SARS-CoV-2 to North American bats could impact populations already threatened by white-nose syndrome and potentially establish a reservoir for the virus or create new variants.
- Precautions for members of the public with bats on their properties, or for people observing bat colonies, have not changed and it is still completely safe to observe bats from a distance. However, as always, bats should never be touched by members of the general public.
- Preventative measures have been recommended for people who work closely with bats for field research, animal rehabilitation, and eviction of bats from buildings (click here for guidance provided by the Canadian Wildlife Health Cooperative)
- People should always avoid direct contact with wild animals to protect wildlife and human health.
What is a coronavirus?
Coronaviruses belong to a well-known family of viruses common in mammals and birds. The virus that causes coronavirus disease 2019 (i.e., COVID-19) is called SARS-CoV-2 and it belongs to this family. Some coronaviruses are zoonotic, which means that they originate in nonhuman animals and have spread to humans. In humans, coronavirus infections can cause a range of diseases from common colds to severe diseases such as Middle East Respiratory Syndrome (caused by MERS-CoV) or Severe Acute Respiratory Syndrome (caused by SARS-CoV).
Can bats transmit coronavirus to people?
There is no evidence to date that bats, or other animals, play any role in the current spread of SARS-CoV-2 among humans. Although research has shown that the ancestor virus of SARS-CoV-2, which causes COVID-19 came from nonhuman animals, the spread of the virus is caused by the direct transmission of SARS-CoV-2 between humans and via contact with contaminated surfaces. A few cases suggest that SARS-CoV-2 can be passed from humans to nonhuman animals (e.g. dogs, cats, tigers, lions, and minks) as well as between some nonhuman animal species. Scientists are working hard to figure out which animal is the natural host of the ancestor of SARS-CoV-2. Researchers suspect that, at some point, a virus infecting a non-human animal mutated in a way that allowed it infect humans. When this occurred, and which animal was the original host, are still unknown. Studies have shown that the genome of SARS-CoV-2 is 96% identical to that of a virus called Bat-CoV-RaTG13 that has been found in a horseshoe bat species (Rhinolophus affinis). However, it is unlikely that Bat-CoV-RaTG13 is the direct ancestor of SARS-CoV-2 because the protein that allows SARS-CoV-2 to bind to and enter human cells differs between these two viruses. Other wildlife species are also carriers of viruses similar to SARS-CoV-2. Some researchers think that the endangered Malayan pangolin (Manis javanica) may have been the animal host for the most recent ancestor of human SARS-CoV-2 because of the binding proteins of a pangolin coronavirus and SARS-CoV-2 are identical. Pangolins are also heavily trafficked as part of the illegal wildlife trade, which has raised suspicion about their possible role as a wildlife host. In short, how, when, and from which animal species SARS-CoV-2 originated is still not known.
What if there is a bat colony on your property?
Precautions for members of the public with bats inhabiting a building, bat house, or natural roost structure (e.g., trees, rock crevices) on their properties have not changed. It is still completely safe to observe bats from a distance. Bats occupying your attic, barn, or other structures on your property pose little risk to humans as long as they do not have regular access to living spaces inside a home. People should still avoid direct contact with bats since, although it is rare, bats can carry rabies. If you are a Bat Watch participant, there are no risks associated with conducting counts of bats emerging from their colonies and, in fact, your counts are now more important than ever because regular fieldwork by bat researchers has been significantly impacted by the pandemic. For more information on how to live in harmony with bats, click here.
Does SARS-CoV-2 threaten North American bats?
The risk of transmission of SARS-CoV-2 from humans to bats is low but, using the precautionary approach, experts have raised the concern that SARS-CoV-2 could spread from humans to North American bats. This could increase negative impacts on bat populations that are already badly affected by white-nose syndrome . Moreover, if SARS-CoV-2 spreads from humans to bats, it could establish a wildlife reservoir for SARS-CoV-2 or create new variants, which would make it very difficult, if not impossible, to eventually eradicate the virus after the pandemic subsides. To prevent transmitting SARS-CoV-2 to bats, experts now recommend (click here for guidance provided by the Canadian Wildlife Health Cooperative):
- Restricting field research involving the capture and handling of bats;
- Wildlife rehabilitation centres to carry out a risk assessement before accepting bats and promoting the release of bats that have entered living spaces when there has been no contact with humans;
- Wearing appropriate Personal Protective Equipment (PPE; i.e. mask, disposable or washable gloves, and protective clothing) during research work with captures, during treatment at rehabilitation centers or when it is necessary to expel bats from a building;
- Not entering spaces where bats are roosting.
The following activities can continue because they present no risk for spreading SARS-CoV-2 to bats:
- Counts of bats emerging from their colonies;
- Acoustic surveys;
- Bat observations from a distance greater than 2 meters.
As noted above, these activities have become even more important for helping monitor bat populations because the handling of bats, and most fieldwork, is currently suspended for biologists. Thus, we continue to be extremely grateful to Bat Watch participants for collecting important data.
Where do zoonotic diseases come from and how to avoid them?
Human population growth, combined with human activities that increase interactions between wildlife and humans, facilitates the transmission of zoonotic diseases. According to the United Nations Environment Program (UNEP), around 75% of all emerging infectious diseases in humans are zoonotic, and these diseases emerge as a side-effect when the health of ecosystems deteriorate.
The best way to protect ourselves from zoonotic diseases is to avoid approaching, touching, manipulating, or feeding wildlife. If contact with wildlife cannot be avoided, it is essential to wear the necessary Personal Protective Equipment. After you are finished coming into contact with animals, it is important to wash your hands with water and soap and decontaminate all the equipment used with a 10% water and bleach solution (9 parts water for 1 part bleach). When the proper precautions are taken, the risks of pathogen spread are minimal. However, if you are ever bitten, scratched, or come into contact with the saliva of a wild bat, click here to learn how to proceed.
To learn more about COVID-19 and bats, visit the following websites: https://www.oie.int/en/scientific-expertise/specific-information-and-re… http://www.batcon.org/resources/media-education/news-room/gen-news/80-l… http://cwhc-rcsf.ca/covid-19.php https://theconversation.com/coronavirus-origins-genome-analysis-suggest… https://www.merlintuttle.org/2020/01/30/wuhan-coronavirus-leads-to-more… https://www.canadianveterinarians.net/coronavirus-covid-19