Brucellosis and Pseudorabies

Lesson 26 of 35 · Module 7, lesson 1

Assumes the Hunting Primer. New here? Start there first.

Your objective

By the end, you'll be able to explain how brucellosis and pseudorabies are transmitted to hunters and their dogs, and what makes each dangerous.

Concept ~8 min

Your dog drops everything and bolts toward the hog you just shot. He sniffs the carcass, mouths it once. Within 48 hours he is scratching uncontrollably, seizing, and dead — and there was nothing to warn you that this hog carried pseudorabies. Meanwhile, you dressed the hog without gloves and now, two weeks later, you have a fever that comes and goes and aches that feel like flu. This lesson names the threats so you can block them before they reach you or your dogs.

Quick recall

Quick recall from Hog Foundations — feral hogs are classified as an invasive nuisance in SC, not game. Why does that matter for disease risk to hunters?

They are never inspected or vaccinated the way domestic livestock are They are more aggressive, so bites are more likely They eat garbage and carrion, which makes them toxic

Show answer

Correct: They are never inspected or vaccinated the way domestic livestock are — Right. Domestic hogs in commercial operations are tested, vaccinated, and monitored. Feral hogs are wild animals carrying whatever diseases they've encountered — with no veterinary oversight at all.
Not quite: They are more aggressive, so bites are more likely — Aggression is a real risk but not the reason disease matters here. The key is that feral hogs carry diseases that domestic hogs are routinely screened and vaccinated for — and feral animals are not.
Not quite: They eat garbage and carrion, which makes them toxic — Feral hogs do eat an omnivorous diet, but the disease risk comes from specific pathogens — bacteria and viruses — not 'toxicity' from diet. The big two are Brucella suis bacteria and the pseudorabies virus.

Swine brucellosis: the hunter’s disease

Swine brucellosis is caused by a bacterium called Brucella suis (pronounced “brue-SEL-uh sue-iss”). It is the number one zoonotic — meaning animal-to-human — disease threat associated with feral hog hunting in North America.

The bacterium lives in blood, lymph nodes, reproductive organs, and abscesses. It is not transmitted by eating cooked pork — heat kills it. The risk is entirely in handling the raw carcass: the pathogen enters your body through broken skin (a cut, a hangnail, a split cuticle), through mucous membranes (eyes, nose, mouth), or through a splash of fluid during field dressing.

Studies of feral swine populations in the Southeast have found Brucella suis antibodies in roughly 10 to 45 percent of tested animals, depending on the region and population. Coastal South Carolina research documented one of the higher rates — over 40 percent in one isolated population. That means in some areas, nearly every other hog you dress could be carrying it.

The why What does undulant fever actually feel like?

The human disease is called undulant fever because the fever rises and falls in waves rather than staying constant. Symptoms usually begin two to four weeks after exposure and include recurring fever, profuse night sweats, chills, deep fatigue, headaches, and muscle and joint pain that can be severe enough to be mistaken for arthritis. Symptoms can disappear for weeks and then return. Without treatment (a prolonged antibiotic course), brucellosis becomes a chronic, debilitating infection. If you develop these symptoms after handling a feral hog, tell your doctor you hunted hogs — that context changes the entire differential diagnosis.

Pseudorabies: the dog killer

Pseudorabies — also called Aujeszky’s disease or “mad itch” — is a herpesvirus that behaves very differently from brucellosis. Here is the key split you need to internalize:

Humans: not at risk. No documented human cases exist. Pseudorabies does not infect people.
Dogs: almost always fatal, typically within 48 hours of contact.

The virus spreads when a dog has direct contact with an infected hog — biting, mouthing, or eating raw tissue. Dogs develop frantic, uncontrollable itching (hence “mad itch”), which rapidly progresses to neurological signs, seizures, and death. There is no effective treatment once symptoms appear, and there is no approved vaccine for hunting dogs in the United States.

Studies in the Southeast have found pseudorabies antibodies in 40 to 60 percent of feral swine in some populations, meaning the exposure risk for a dog that contacts a hog carcass is substantial and cannot be judged by how healthy the hog looked.

The why Why can't we vaccinate hunting dogs against pseudorabies?

A vaccine exists for domestic swine (it protects pigs but does not prevent them from carrying the virus), but there is no approved pseudorabies vaccine for dogs in the U.S. The approved domestic swine vaccine is not labeled for canine use. Research is ongoing, but as of now, the only reliable protection for hunting dogs is preventing contact with infected feral swine or their tissues entirely.

How both threats enter your body

The diagram below maps the two disease pathways side by side. The most important takeaway: both risks are blocked by the same action — wearing impermeable gloves before you touch the carcass.

Schematic showing two disease transmission pathways. Left side shows Brucella suis bacteria leaving a hog's blood and organs, traveling via cut skin or mucous membrane splash to a human figure labeled 'Hunter at risk'. Right side shows pseudorabies virus leaving hog tissue, traveling to a dog figure labeled 'Dog: fatal within 48 hours'. A barrier labeled Double impermeable gloves + no dog contact blocks both pathways. — Diagram (not a photo). Both headline feral-swine diseases share a common entry point — direct carcass contact. Double impermeable gloves block the brucellosis pathway; keeping dogs away from the carcass blocks the pseudorabies pathway.

Check your understanding

Knowledge check

A hunting partner says: 'Pseudorabies is dangerous, but at least it can't kill me — I'm just worried about eating the meat.' What is wrong with this statement?

He is ignoring the fatal risk to his dogs from any contact with the raw carcass He is wrong — pseudorabies can also infect humans He is wrong — the meat is not safe to eat even after cooking

Show answer

Correct: He is ignoring the fatal risk to his dogs from any contact with the raw carcass — Correct. He is right that pseudorabies does not infect humans, and right that properly cooked meat is safe. But he is missing the point: his dog can die within 48 hours from brief contact with an infected hog carcass. The human 'I'm fine' framing obscures the dog-safety problem entirely.
Not quite: He is wrong — pseudorabies can also infect humans — Actually, no documented human cases of pseudorabies exist. The statement is correct that humans are not at risk. The problem is his reasoning about the whole picture — his dogs are in serious danger from carcass contact.
Not quite: He is wrong — the meat is not safe to eat even after cooking — Properly cooked hog meat (160°F internal temperature) is safe to eat. The cooking process addresses food safety concerns. The issue is the raw-handling risk — for brucellosis in humans, and for dogs from pseudorabies.

Knowledge check

Which of the following correctly describes how hunters get brucellosis from feral hogs?

Through contact between the hog's blood or organs and the hunter's broken skin, eyes, nose, or mouth during field dressing By eating cooked hog meat that was not inspected By breathing near a live hog or its feces

Show answer

Correct: Through contact between the hog's blood or organs and the hunter's broken skin, eyes, nose, or mouth during field dressing — Exactly right. Brucella suis lives in blood, reproductive organs, and lymph nodes. It enters the human body through mucous membranes or broken skin — the exact exposures that happen when you field dress a hog without gloves.
Not quite: By eating cooked hog meat that was not inspected — Cooking kills Brucella suis. You cannot get brucellosis from properly cooked pork. The risk is in handling the raw carcass, not in eating the meat after it has reached a safe internal temperature.
Not quite: By breathing near a live hog or its feces — Aerosol transmission of Brucella suis is theoretically possible in rare circumstances (like industrial slaughter settings) but is not the primary hunter exposure route. The dominant risk for hunters is direct contact with blood and organs during field dressing.

Take it to the woods

Before you touch that carcass

0/5

Safety Double-glove with impermeable (rubber or nitrile) gloves before touching the hog — before you roll the hog, before you draw a knife. No exceptions. The hog that looked healthy can still carry Brucella suis.
Safety Secure your dog away from the carcass before you approach — leashed, in the truck, or otherwise controlled. Pseudorabies is fatal to dogs and there is no treatment. One mouth on raw tissue is enough.
Consider safety glasses if you expect fluid splashing — gut incisions spray.
Cover any hand cuts or open skin before putting gloves on — glove layers protect, but an intact barrier is better.
Note the date of any hog-handling for your records — if you get flu-like symptoms in the next 2–4 weeks, tell your doctor you hunted hogs.

Sources

SCDNR Feral Hog Damage and Diseases: https://www.dnr.sc.gov/wildlife/hog/damage.html
SCDNR Safe Handling of Feral Hogs: https://dnr.sc.gov/wildlife/hog/safehandle.html
Clemson University — Brucellosis in Wild/Feral Pigs: https://www.clemson.edu/public/lph/ahp/reportable-diseases/livestock-disease/brucellosis-pigs.html
Florida FWC — Pseudorabies in Feral Swine: https://myfwc.com/research/wildlife/health/feral-swine/pseudorabies/
USDA APHIS — Brucellosis and Hog Hunters (PDF): https://www.aphis.usda.gov/sites/default/files/brucellosis_and_hoghunters.pdf
PubMed — Brucella suis and PRV in coastal SC feral swine (Olsen et al. 2002): https://pubmed.ncbi.nlm.nih.gov/12238392/
PubMed — Pseudorabies in hunting dogs after feral swine contact (Schoenbaum et al. 2019): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6282367/

If you remember nothing else

Swine brucellosis is a bacterial infection that can jump from hog blood and organs to humans through cuts, mucous membranes, or eye splashes during field dressing.
Roughly one in ten feral hogs across the Southeast carries Brucella suis antibodies — some areas run far higher.
Human brucellosis (undulant fever) causes recurring fever, chills, joint pain, and fatigue — weeks after exposure.
Pseudorabies is a herpesvirus that does not infect humans, but it is almost always fatal to dogs within 48 hours of contact with an infected hog.
The only reliable protection against both is wearing impermeable gloves before you ever touch the carcass.

How ready do you feel?

How ready are you to explain these two diseases to a hunting partner and tell them exactly how exposure happens?

Before you go — a quick look back

Distributed practice: one fast recall from an earlier lesson keeps it from fading.

Quick recall

From Sounder Biology — why does the whole-sounder removal strategy matter so much for disease control?

Show me the answer

Show answer

Correct: Show me the answer — Feral hogs reproduce explosively and carry diseases like brucellosis at high rates across entire sounders. Removing only part of a group leaves infected animals to breed back quickly, making disease exposure a recurring risk. Whole-sounder removal cuts the population and its disease reservoir at once.

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