CWD Transmission Pathways - How does CWD enter your farm?

Chronic wasting disease can be spread to your herd through multiple direct and indirect pathways.

One method is direct transmission pathways of CWD to an uninfected farmed cervid herd:

  • Direct transmission of CWD can occur through the movement of farmed cervids. Importing an infected farmed cervid into a non-infected herd can result in direct transmission from that infected cervid to the resident herd through direct physical contacts with other animals on the farm.  For this reason, surveillance is in place on all cervid operations, though the usual surveillance is limited by testing only of tissues of dead cervids.  
  • There can also be direct contact with an infected wild cervid through a breach in the perimeter fence. If an infected wild deer enters the pen through a fencing breach, or if escaped farmed cervids are allowed re-entry into your pens after interacting with infected wild cervids, your animals may be infected.  It is also possible that transmission from nose-to-nose contact could occur through the fence if single fencing is used, though this is considered unlikely at the present time.

The other method is through indirect transmission pathways of CWD to an uninfected farmed cervid herd:

  • There can be indirect contact from an infected cervid farm.  While sharing of equipment from known CWD-infected operations is prohibited, sharing of equipment with other operations is allowed, and some of these operations may be recently infected and not yet detected.  Sharing of contaminated equipment (including reproductive or veterinary supplies), vehicles entering your farm, contaminated feed or water, use of semen or embryos from a CWD-infected farmed cervid herd that has not yet tested positive could result in the transmission of CWD to your herd.
  • In addition, indirect transmission may occur from CWD-infected wild deer to susceptible cervids through contaminated feeds, water, or through environmental contamination from other animals, including wild and domestic scavengers.  If feed is harvested from an area where CWD is endemic in the wild, it can become contaminated and when harvested could potentially spread prions. Birds or mammalian scavengers can bring contaminated material into the pens through carrying infected material on their haircoats or through their feces.
  • One should also consider who is entering areas where their cervids reside. Hunting preserves may have hunters from all over the world and the United States come onto their land to hunt. Hunter participants could indirectly bring infected dirt or organic material on their boots or clothing when entering the preserve. Same with workers who work on multiple cervid farms or hunt in their spare time.
  • Finally, indirect transmission of CWD can occur through contact with infected cervid parts or carcasses through hunting or taxidermy practices brought back to the farm. If your cervids come in contact with infected material, transmission of CWD may occur. If hunting in an area where CWD is in the wild cervid population (and the environment), infected dirt and other organic material from the environment can be tracked from the hunting area to your operation via vehicles, boots, clothing, or other hunting equipment.