As the number of human coronavirus infections continues to rise world-wide, there is some uncertainty about the role animals play in the COVID-19 virus epidemic. In this article, we try to summarize and interpret the available information in this rapidly evolving situation.
Corona viruses are common in humans and animals, some of them are zoonotic (can be transmitted to humans from animals). The novel 2019 coronavirus (COVID-19 virus or SARS-CoV-2) is a new strain that is thought to originate from an animal source. Investigations on the identification of the source animal species are on-going. So far, the closest match to the human coronavirus was found in a bat in China. Sequencing data show that the human virus shares 96% of their sequence with the virus found in multiple species of bats in the genus Rhinolophus, but differs in an essential part, the receptor binding domain. This suggests that this specific bat coronavirus did not directly infect people, but could have been transmitted to people through an intermediate host. Which animal species served as intermediate host in this case is still subject to speculation.
The highest risk for COVID-19 virus infection is human-to-human transmission, but what part do animals play in the development of the current pandemic and can animals be infected at all?
Animals, especially pets, can get contaminated by the virus by contact with infected humans. The WHO advises to wash hands after contact with animals to prevent contamination. There is, however, also limited evidence that companion animals can be infected with SARS-CoV-2 , but no evidence so far suggest that pet dogs or cats can be infectious to other animals or to humans. The US Centers for Disease Control and Prevention (CDC), the World Organization for Animal Health, OIE and other international organizations recommend that people sick with COVID-19 limit contact with animals until more information is known about the virus.
The OIE has defined investigating the role of domestic animals and livestock in the current COVID-19 outbreak as one of the research priorities. First experiments have been started by the Friedrich-Loeffler-Institute (FLI) in Germany to study the novel coronavirus in pigs, chickens, ferrets and Nile flying foxes.
The detection of COVID-19 virus in animals meets the criteria for reporting to the OIE through WAHIS, in accordance with the OIE Terrestrial Animal Health Code as an emerging disease. Therefore, animals that are found positive for the COVID-19 virus should be reported to the OIE. The identification of animal hosts is an important additional measure so that other (rare) spill over events can be prevented in future (See OIE Animal and environmental investigations to identify the zoonotic source of the COVID-19 Virus, Zoom conference, Friday 31 January 2020) .
There have also not been any reports of transmission via the consumption of animal products (EFSA).
So, it is likely that animals did play a role in the origin of the epidemic. At the moment, transmission seems to be predominantly human-to-human and there is no evidence that animals play any role in the propagation of the infection.
COVID-19 is not the first disease to pass from animals to humans. As human-animal interactions are intensifying we cannot exclude future spill-over events. The occurrence of the pandemic teaches us that we need to adopt a fully integrated approach, a One Health vision, where human health, animal health, and the environment are monitored together. See also our letter to the editor published in Transboundary and Emerging Diseases.
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