Final report on research into Covid in deer in the Netherlands
Joint report from the Dutch Wildlife Health Centre, Erasmus MC, the National Institute for Public Health and the Environment, and Wageningen Bioveterinary Research, with thanks to the Royal Dutch Hunters’ Association (KNJV), Zuid-Kennemerland National Park, and Waternet.
After white-tailed deer in the United States and Canada tested positive for SARS-CoV-2 in August 2021, and research showed they had also transmitted the infection to other deer, the World Organisation for Animal Health (WOAH) urged all countries to investigate SARS-CoV-2 in cervids. Research has been conducted in several European countries, including the Netherlands. In the Netherlands, samples from fallow deer and roe deer were tested for the SARS-CoV-2 virus in 2022. No virus or antibodies were detected.
Background
In the United States and Canada, white-tailed deer tested positive for SARS-CoV-2. Multiple studies have shown that the white-tailed deer not only became infected but also transmitted the infection to other deer. Therefore, the World Organisation for Animal Health (WOAH), formerly the OIE, has urged all countries to investigate SARS-CoV-2 in cervids. Research is being conducted in several European countries, although white-tailed deer are not found in the wild.
In addition, the Dutch Wildlife Health Centre (DWHC) received several inquiries from concerned wildlife managers about roe deer with lung problems. Research indicated that lungworms were the primary cause, but it is still important to rule out COVID-19 as a contributing cause.
In the Netherlands, the research focuses on fallow deer in the dunes, roe deer across the country, and cervids submitted to the DWHC for investigation into the cause of death.
Fallow deer were chosen because, like white-tailed deer, they live in (small) herds and the dunes receive many visitors, potentially posing an increased risk for humans of exposure to the virus. Roe deer are genetically closer to white-tailed deer than fallow deer. Therefore, it is important to also test roe deer for SARS-CoV-2.
Method and Implementation
Nasal swabs (was the animal infected with the SARS-CoV-2 virus at the time of sampling) and blood samples (was the animal previously exposed to or infected with the virus) were taken from fallow deer and roe deer shot as part of wildlife management. The wildlife managers of the Amsterdam Water Supply Dunes (Waternet) and Zuid-Kennemerland National Park took the samples from the fallow deer. The roe deer were sampled by hunters through the Royal Dutch Hunters’ Association (KNJ). The roe deer samples primarily came from North Brabant (19/25). Lung and blood samples from roe deer, fallow deer, and red deer were also tested from the DWHC biobank. Most fallow deer samples were taken between January 24 and February 4, 2022. A few more samples were taken between February 21 and March 31, 2022. The roe deer testing period ran from April 1 to October 15, 2022. In addition, samples from cervids submitted to the DWHC for testing in 2020, 2021, and 2022 were also tested for the SARS-CoV-2 virus.
The results
164 samples were received from fallow deer, 25 from roe deer, and 54 animals from the DWHC biobank were tested (1 fallow deer, 2 red deer, 37 roe deer). Both nasal swabs and lung samples were negative for the SARS-CoV-2 virus. No SARS-CoV-2 antibodies were detected in any of the blood samples.
Conclusion
The test results show that the tested fallow deer and roe deer were likely not exposed to the SARS-CoV-2 virus, either at the time of the study or in the preceding months.
The results of the study are included in the RIVM report “State of Zoonoses 2022,” which will be available online on October 13, 2023: https://www.onehealth.nl/staat-van-zoonosen-2022
Results in other European countries:
Negative test results in Europe:
No SARS-CoV-2 was found in red deer and fallow deer in the United Kingdom, Germany, Austria, and Poland.
Positive test results in Europe:
In Dublin, Ireland, antibodies to SARS-CoV-2 were detected in fallow deer in a city park. These fallow deer have therefore been exposed to the virus. The fallow deer in this park are hand-fed by people.
In Spain, antibodies were detected in 4 fallow deer and 2 red deer. The four fallow deer and one red deer came from a city park, while the other red deer came from a rural area. All roe deer samples were negative.
More information about SARS-CoV-2 in cervids can be found in:
https://www.theguardian.com/world/2021/nov/11/us-covid-wildlife-virus
