5 Strange Parasites That Infect Deer

   11.07.14

Earlier this week we covered five common diseases that plague deer in North America, but we also left off an entire section of ailments: parasites. These crawly, wriggly, oozing pests are common in many deer, and can be very damaging to the animal they inhabit—not to mention being very uncomfortable and gross-looking as well. The odds are, if you’re an avid deer hunter, you probably already encountered at least one of these before. Thankfully, none of them are harmful to humans and cannot infect people, making them little more than an annoyance for many hunters. Most of the time these tiny critters don’t even ruin the meat, although you will want to give the venison a through cleaning before consumption.

Be warned, the images and videos below can be graphic. If you have a weak stomach, click away now.

If you think you would sleep better never knowing about these parasites, this is the time to turn back. Otherwise, let’s jump into the five deer parasites that make us itchy just by looking at them.

Arterial worm (lumpy jaw)

This deer, which seems to have lump jaw, has a strange pouch under his mouth due to impacted food.
This deer, which seems to have lump jaw, has a strange pouch under his mouth due to impacted food.

Have you ever seen a deer with large lump on the side of its mouth, sort of like if it was trying to store food the same way that a squirrel does? Well then you probably saw a deer with arterial worms, or “lumpy jaw” as it’s commonly called. According to the Maryland Department of Natural Resources, arterial worms live in a deer’s carotid arteries and can reduce bloodflow to the animals jaw. This causes the deer’s jaw muscles to become partially paralyzed. The lump is actually “impacted” food that the deer has already chewed but is unable to swallow. Needless to say, lumpy jaw can cause mortality in deer, especially older animals who find themselves unable to eat entirely.

Experts believe that arterial worms don’t affect humans, and no case of a human contracting the parasite has been reported.

You can see video of a deer with lumpy jaw below:

Nasal bots

Think you're congested? These nasal bots can grow to over an inch long!
Think you’re congested? These nasal bots can grow to over an inch long! Image taken from video below.

These disgusting botflies have been reported in just about everywhere in North America, except for a few lucky locations in Ohio, Kentucky, Tennessee, or Alabama. According to the Michigan Department of Natural Resources, there are at least five species of these botflies that infect cervids such as mule deer, moose, and whitetails. Deer get this ailment from passing female botflies, which inject hatched larvae directly into the nose of the host. The larvae, which can number several dozen, then move to the base of the deer’s tongue and either side of the throat, where they congregate in clusters.

Here, the larvae find a nice, warm place to grow until they are eventually evicted. At that time, they will burrow into the ground and enter a pupal period lasting about two to three weeks, at the end of which they will emerge as adult botflies and continue the cycle. Despite their size, nasal botflies are actually relatively harmless to deer and biologists consider treatment impractical and unnecessary. The only way nasal flies can become lethal for a deer is if the larvae migrate to the lungs, but it is an extremely rare occurance. The most common visible symptom is inflammation inside the throat.

Botflies, other than being completely disgusting, are not harmful to humans if handled correctly.

You can see an example of nasal bots below:

Liver fluke

Damage to a roe deer liver caused by flukes. Image taken from video below.
Damage to a roe deer liver caused by flukes. Image taken from video below.

You can find these flat, oval-shaped worms in a deer’s liver. To some, they resemble leeches, while to others, they look like a bizarre blood clot. In many cases, flukes cause little ill effect on their host, yet some deer do develop liver damage or get infected as a result of the fluke’s movements. Other animals, such as sheep, fare much worse and even two or three of these parasites will be enough to cause death.

Flukes are cunning little parasites, and get into deer by attaching themselves to vegetation that deer like. Once inside, the fluke larvae will punch its way through the intestine wall and reach the liver. After three months, the mature fluke then lays eggs in liver cavities, which are drained to the intestinal tract and later flushed out as feces, beginning the cycle anew.

READ NOW: How to recognize 5 common deer diseases

A liver infected with flukes is safe to eat once properly cleaned, and poses no risk to humans.

You can see the identification of a fluke in the video below, it might be helpful to turn the captions on:

Large lungworm

Lung with dark areas where parasites have caused damage. Image courtesy Alaska Department of Fish and Game.
Lung with dark areas where parasites have caused damage. Image courtesy Alaska Department of Fish and Game.

In many ways, lungworms are similar to flukes. These parasitic nematodes resemble long strings or spaghetti, and can be found in the lungs of many deer. They get into deer through the same process as liver flukes, but unlike flukes, lungworms can cause a host of health problems for deer. These parasites can cause a buildup of mucus in the respiratory tract that block airflow, making it difficult for an infected animal to breathe. Fawns are especially vulnerable to infection and in unmanaged deer herds, lungworms can be a significant source of mortality. Common symptoms of lungworm include coughing, wheezing, and significant weight loss.

Lungworm can also be found in many other animals such as cows, horses, pigs, and domestic pets. The parasite cannot infect humans and is generally considered harmless to people.

Brain worm

A biologist points out a brain worm within a deer skull.
A biologist points out a brain worm within a deer skull. Image courtesy Michigan Department of Natural Resources.

The brain worm is perhaps one of the weirder and more complex deer parasites. This roundworm is found in most places with a whitetail population and is fairly common in Eastern states. Although adult brain worms live in the subdural space of the brain, these parasites can be found throughout the deer in varying stages of its life cycle. The brain worm enters a deer while the animal is browsing and will travel along the spinal column up into the brain. For the most part, signs of the parasite in deer are hard to spot. Some biologists have reported neurological symptoms after infection. This can include spasms, walking aimlessly in circles, and other bizarre behavior.

Brain worm infection in elk is significantly more severe and often ends in death. Because brain worm infections are so common, wildlife officials consider the parasite to be a somewhat high concern, especially near elk, moose, and caribou populations. Like the others on this list, the worm does not affect humans and will not ruin the meat of infected animals.

What’s the weirdest thing you’ve ever found in your deer? Tell us in the comments below.

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