Parasites of deer are not uncommon

Published 12:21 pm Wednesday, November 22, 2023

By James L. Cummins

Many of you may have encountered several parasites or diseases that white-tailed deer are susceptible to as you were cleaning a deer after a successful outing. The spread of disease is most common in herds with high deer density, although outbreaks seldom impact the quality of venison. 

However, any deer that appears to be ill due to systemic disease should be considered unfit for consumption. Here we will look at some of the parasites found among deer.

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Ticks. There are reportedly 18 tick species known to infect deer. Most often, deer with tick infections exhibit few to no symptoms. However, those with severe tick infections may present with irritated skin around the tick site, poor body condition, weight loss, and other secondary infections.

Large Stomach Worm. Deer can carry low to moderate amounts of this parasite and be symptom free. However, large quantities of this parasite can cause the deer to become weak, anemic, underweight, and overall malnourished. Once infected, eggs are eliminated through the deer’s waste, and the larvae crawl onto surrounding vegetation where they are picked up by other deer during feeding. Although this sounds extremely unpleasant, these parasites pose no harm to humans.

Arterial Worms. Infected horseflies are to blame for this parasite being transmitted among white-tailed deer. Once delivered through the bite of a horsefly, the larvae migrate to the carotid arteries in the deer’s neck. When only a small number of worms are present, the deer is likely to exhibit no symptoms of infection. However, when large numbers are present, blood flow to the jaw muscles is reduced causing diminished nutrition absorption and can lead to emaciation as well as secondary infections at the site of food impaction.

Ear Mites. Caused by a specific species of mite, most deer demonstrate no signs of having ear mites. However, severe infestations have been shown to cause secondary infections of the inner ear which may cause the deer to become clumsy and uncoordinated—much like humans with inner ear infections.

Abdominal Worm. Not to be confused with the large stomach worm, this worm lives freely in the abdominal cavity among, but not inside, the deer’s organs. Transmitted through mosquito bites and appearing as thin, white noodles, these worms can often be seen by hunters during field-dressing.

Liver Fluke. One to three inches in length, the liver fluke looks much like a leech in the adult stage. Feeding on blood, the liver fluke takes up residence in capsules inside the deer’s liver. Eggs are passed in the deer’s scat.

Demodectic Mange. This is caused by a specific species of mange mite. Deer infected with mange will present with hair loss and skin thickening with small, pus-filled lesions. It is primarily spread through contact with another infected deer and can be fatal to deer, especially fawns. However, because mange infections are limited to the skin, the meat is safe for human consumption.

For more information on diseases and parasites, visit the Mississippi State University Deer lab website at

James L. Cummins is executive director of Wildlife Mississippi, a non-profit, conservation organization founded to conserve, restore, and enhance fish, wildlife, and plant resources throughout Mississippi. Their website is