The novel coronavirus SARS-CoV-2 responsible for the current pandemic is phylogenetically related to bat coronaviruses (CoVs), in particular the Bat-CoV-RaTG13 virus, which has been detected in a Chinese bat species of the Rhinolophidae family. While bat coronaviruses have been shown to have never been transmitted directly to humans, and the conversely, the possible effects of SARS-CoV-2 on bat populations are unknown, as well as the ability of bats to serve as a reservoir or intermediate host that can transmit the virus back to humans or other animal species. To study the effects of SARS-CoV-2 on bats, a North American research team has attempted to experimentally infect the big brown bat(Eptesicus fuscus)under laboratory conditions. They inoculated the virus into the bats. both oral and nasal, and then examined the animals over a three-week period in terms of infectivity, pathology, tissue virus concentration, oral and rectal viral excretion, virus transmission and clinical signs of disease. None of the bats studied had shown signs of SARS-CoV-2 infection. Based on these results, the authors conclude that big brown bats are resistant to SARS-CoV-2 infection. However, the potential vulnerability of other North American or Eurasian bat species to SARS-CoV-2 has yet to be investigated.
Although this study provides further evidence that transmission of SARS-CoV-2 to bats is highly unlikely, we continue to advise caution. Bats, due to their unique immune system, are able to deal with many different pathogens, including coronaviruses, without contracting them themselves or passing them on to their conspecifics. Nevertheless, the experimental study of the Friedrich-Löffler-Institute demonstrated an experimental infection of SARS-CoV-2 to flying foxes (see previous reports). Thus, it remains to be clarified which bat species are vulnerable for SARS-CoV-2. There could be differences in species, which is why no definitive warning can yet be given on the basis of the North American study described above.
If, contrary to all probability, a transmission takes place and a new reservoir of SARS-CoV-2 is formed in the animals, this would have serious negative consequences for bat protection.
In the upcoming weeks, many bat workers will participate in hibernacula inspectionsto count individuals and collect data that allow conclusions about population developments. During these inspections, it is also advisable to exercise appropriate caution. In doing so, not only the well-known rules of how to conduct such hibernacula visits should be followed, which are intended to prevent arousals from hibernation and thus to avoid disturbance of the sensitive animals from hibernation, but also extended hygiene measures in relation to SARS-CoV-2 should be taken.
In the recommendation for action of April 2020, which was written by Fledermauswarte, Bundesverband für Fledermauskunde, Noctalis and Berliner Artenschutzteam, we have already given some hints on the implementation of bat roost inspections. As a reminder, we would like to point out that these measures are also effective for hibernacula inspections. The most important measure recommended is the wearing of gloves and a mask. In addition, where possible, a minimum distance of 2 m from the animals should be kept. The visit in small-scale hibernation sites should be limited to a minimally necessary number of persons, as well as the visit duration should be no longer than 15 min in the sites. Bat workers who have tested positive for SARS-CoV-2 or show symptoms of the disease are not allowed to enter hibernation sites. In case of doubt, an antigen test is recommended in advance. Utensils necessary for surveying should be disinfected or disposed of before and after use.
Reference of the study described above:
Hall, Jeffrey S.; Susan Knowles, Sean W. Nashold, Hon S. Ip, Ariel E. Leon, Tonie Rocke, Saskia Keller, Mariano Carossino, Udeni Balasuriya, Erik Hofmeister (2020): Experimental challenge of a North American bat species, big brown bat (Eptesicus fuscus), with SARS-CoV-2. Transboundary and Emerging diseases (in press). URL: https://onlinelibrary.wiley.com/doi/10.1111/tbed.13949