3 does in field

The state of current affairs has disrupted almost every aspect of our lives. No parties, no playgrounds, no races, no restaurants, no concerts, no conferences! All of us are quite familiar with the term social distancing now.

Social distancing is not a new concept to those in public health or anyone who deals with disease issues. Sure, it all seems extreme as we have never had to address this type of public health crisis before but this is a common strategy to slow (and hopefully stop) the spread of disease. 

I am fascinated by disease and its management. I probably should have been a disease ecologist, but I had no idea that was even a thing. As a wildlife biologist, I still get to dabble. Deer have lots of interesting afflictions. 

Big ones, of course, are chronic wasting disease (CWD) and bovine tuberculosis (bTB). Both contagious, transmitted directly between animals and from doorknobs (i.e. the environment). However, there are lots of infectious diseases and parasites deer can get. Lice, miteshemorrhagic disease, lung worm, cutanious fibromarabiespseudorabiesdermatophilosisbrucellosis – should I go on?

What is a wildlife biologist’s first response to any of these diseases? Social distancing! Before the COVID-19 pandemic, I didn’t have a term for it, but I sure do now. Many diseases, if not all, are exacerbated and perpetuated by the congregation of animals. 


You’ve probably heard about R0 (R naught) in the news. It’s a measure of how contagious a disease is. If that value is less than 1 (i.e. 1 infected deer infects less than 1 other deer), the infection cannot be sustained in the population and it disappears. If it equals 1, the disease hangs around but doesn’t get out of control. If it is greater than 1, one infection causes multiple new infections and an outbreak or epidemic is possible.

The whole point of socially distancing is to reduce the R0 value. Keeping an infected deer away from healthy deer will prevent transmission, lower the R0 value, and hopefully the infection will peter out or stabilize. 

Deer suck at social distancing. Always carpooling when traveling, visiting the neighbors, going out to eat, combing each other’s hair – you never see a deer alone and they rarely follow the 6-feet-apart rule! This makes things much worse. Indeed, all evidence from the self-sustaining bTB infection in free-ranging deer in Michigan points to high deer densities and concentration caused by feeding.

How do wildlife managers mandate social distancing in a social animal? 

Close the restaurants and bars. While deer still can go out to obtain essential items, YOU must close your facility. That’s right – STOP FEEDING DEER. 

deer feeding on cob corn in snow

Sharing corn-filled plates and licking the same mineral lollipop are sure to keep any nasty bug going (Hello Michigan). And I can guarantee that no deer covers its cough or sneeze at a corn pile. 

The second way wildlife managers can enforce social distancing with species like deer is to have fewer of them. Reducing the population reduces the contact rate among individuals especially those that are infected. This is probably the most effective tool we have in combatting wildlife disease outbreaks. This strategy was used to fight bTB in deer in Minnesota and in badgers in England

Like many, I have been following the current human pandemic closely and I couldn’t help but see some parallels with Pennsylvania’s most talked about wildlife pandemic, CWD.

CWD is like COVID-19 in super-slow motion. Even with hundreds of new cases every day, it was still difficult for state and federal agencies to enact public health strategies to slow COVID-19 down. With an incubation period of 18-24 months, CWD moves much slower but action still needs to be taken. Pennsylvania is on track to double its total number of CWD positives in just one year. 

The current public health crisis rightly overshadows any wildlife disease issue. Hopefully, actions taken will reduce R0 – people’s lives are depending on it. But human health is wrapped up in wildlife health. Over 40% of emerging human parasite and pathogens originate in wildlife, not to mention the conservation challenges it raises (e.g. white-nose syndrome). 

The answers are never easy and always cause inconvenience, unhappiness, pain, and hardship. Fewer deer do not make hunters happy. Canceling a race for which I’ve been training 3 months does not make me happy. A better tomorrow sometimes means a completely terrible today. 

-Jeannine Fleegle
Wildlife Biologist

PGC Deer and Elk Section

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