Oh Deer! Are Your Animal Neighbors Passing Along COVID?

From the rapid transcontinental spread of the SARS-CoV-2 virus to the impact of snarled supply lines, the pandemic provided one object lesson after another about how interconnected we all are. Now University of Maryland researchers will investigate another potential COVID link—this one between humans and one of the most commonly seen animal visitors in our neighborhoods.

A new $3.6 million cooperative agreement from the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS will fund an investigation into how, where and when white-tailed deer interact with humans in and around Washington, D.C,. and assess their potential role in transmitting COVID-19 and other respiratory diseases like influenza, as well as the risk of the deer becoming a reservoir for such viruses.

The study is part of a larger effort by APHIS to build an early warning system to prevent or limit future zoonotic disease outbreaks, and it falls under the agency’s One Health initiatives, which focus on the vital relationships between the health of humans, animals, plants and the environment.

As the study gets underway this winter, Assistant Professor Travis Gallo and Associate Professor Jennifer Mullinax, both of the Department of Environmental Science and Technology, will place GPS tracking collars on at least 45 white-tailed deer and take nasal swabs and blood samples for lab analysis.

The collars will transmit information back to the researchers about deer movements over two years, and the blood samples will reveal the prevalence of SARS-CoV-2 and other diseases in the deer population.

Combining this data with human movement data from cell phones, the researchers will be able to pinpoint locations and times of human-deer encounters. Research teams will also conduct field observations and interviews in areas of high human-deer interaction to better understand the various types of interactions such as feeding, chasing, or pet-deer encounters.

Finally, the team will estimate the potential transmission rates of SARS-CoV-2 between deer and humans by sequencing positive blood samples among the collared deer to understand which strains of the disease are present in deer and how the disease might move between deer and humans.

Previous APHIS research showed that COVID-19 has spread widely within deer populations; Mullinax’s recent research, meanwhile, has shown how closely deer live to human populations, including frequently bedding down for the night within feet of houses.

“We’re trying to put this all into one big picture of how humans and deer move around the landscape and the probability of deer to human disease transmission throughout the landscape across time,” said Gallo, the lead scientist on the grant. “Then we can use a predictive model to ask questions about potential interventions like, controlling the deer population in certain areas, educating people about interacting with deer, or even giving deer vaccines, to predict if we can reduce the risk and rates of disease transmission."

The findings will support decision-makers in mitigating potential disease spread between humans and urban wildlife, including hikers, dog walkers, landowners and more. In addition, this project will contribute valuable data and surveillance tools to monitor zoonotic diseases beyond SARS-CoV-2.