One of the many interesting topics covered at Michigan’s Chronic Wasting Disease Symposium was the multiple transmission mechanisms that exist for contracting CWD.
Mike Samuel, PhD., of the University of Wisconsin covered many of the known CWD pathways. Prions, the infectious particles that many scientists believe cause CWD, have been found in the bodily fluids of infected cervids (deer, elk and moose), including blood, feces, saliva and urine. Direct contact between a healthy deer and the bodily fluids of a sick deer can spread CWD.
“We believe that saliva and blood are most infective,” said Samuel. “Feces is below blood and saliva, and urine is at the lower end in terms of the number of prions it contains.”
Now you may wonder: how do deer come into contact with blood from infected critters?
“Bucks are known to lick the blood from the pedicles of another buck after the animal sheds its antlers,” Samuel added. “Deer are very social and will often groom each other, coming into direct contact with blood and many other bodily fluids.
Researchers have also documented that sick animals shed prions through their bodily fluids into the environment, creating tons of potential transmission sites. Healthy deer that encounter bodily fluids deposited by infected animals are susceptible to contracting CWD.
Other environmental transmission mechanisms include wherever carcasses from sick deer are deposited by hunters, and wherever sick body parts are carried and/or spread by predators.
“We think that anywhere deer are concentrated increases the risk of transmitting CWD, such as at feeding and baiting sites, mineral licks, food sources, and even in plants, which we’ve found can uptake prions and then are ingested by animals,” explained Samuels.
Scientists don’t know how important each transmission mechanism is to causing CWD, or how much infected material healthy deer must consume to get CWD. More on how CWD is transmitted in future posts – so stay tuned!