Friday, November 21, 2014

Common Deer Parasites Do Not Affect Venison

Displaying eo20141121_strickland.jpg
Bronson Strickland
While dressing a deer this fall, there are some common parasites you may encounter. None of these parasites actually affects the quality of the deer meat, but it is important to recognize what they are.

Louse flies…
Have you ever noticed little wingless critters crawling around on a deer’s belly? Those are louse flies -- also called deer keds. The adult flies shed their wings and become flightless.  While at first glance louse flies         resemble small ticks, they only have six legs.

The deer serves as a host during part of the louse fly’s life cycle. The wingless adult fly produces eggs, which grow to larvae and pupae and then fall off the deer. On the ground, the winged adult emerges from the pupa and searches for another deer to start the cycle over again.

Bot flies…   Have you seen a deer during the summer running and jumping around swinging its head back and forth? More than likely, this deer is trying to avoid a bot fly. The bot fly will use a deer as a host to incubate its larvae by landing on the deer’s nose and quickly depositing eggs. The eggs will then migrate to the deer’s nasal cavity and begin to grow.

I’ve received many phone calls over the years describing “fat little worms” that fall out of the deer’s mouth and nose while it is hanging upside down on the skinning rack. These are simply the larvae of the bot fly.

Other than being extremely uncomfortable for the deer -- imagine having a stuffy nose for months -- the larvae pose no health risk to the deer and will naturally migrate out of the nasal cavity when mature. The venison is perfectly fine to eat.

Arterial worms…

A third common parasite of deer is a nematode called an arterial worm. A symptom of this parasite is what appears to be a swollen jaw, or a mouth full of cud. It is often referred to as lumpy jaw.

The worm lodges itself in the deer’s carotid artery, clogging the artery and reducing blood flow to the jaw. In turn, the jaw becomes weak, often resulting in food getting forcibly wedged in the deer’s mouth. This food impaction may also lead to tooth loss.

Larvae produced by the female arterial worm will slowly migrate through the deer’s circulatory system and become ingested by horse flies that feed on the deer’s blood. The horse fly then feeds on another deer, depositing the arterial worm larvae in the bloodstream of a new host. The larvae grow to adult worms, and the cycle begins again.

If you run across a deer with one of these common parasite infections this season, don’t be alarmed. While these parasites may be uncomfortable to the infected deer or cause the deer to look deformed, remember they do not affect the meat in any way.

For more information on common deer parasites, visit the Mississippi State University Deer Lab web site,

By Bronson Strickland
Wildlife Biologist and Wildlife Management Specialist
MSU Extension Service