Can Raw Milk Cause Brucellosis?

By Dr Duncan Houston

Raw milk can look natural, traditional and wholesome, but it can also carry bacteria that pasteurization was designed to remove.

Raw milk is having a very strange modern rebrand.

It is often marketed as cleaner, more natural, more nutritious, or somehow more “real” than pasteurized milk. The problem is that bacteria do not care about branding. Milk can come from a clean-looking farm, a healthy-looking animal, and a licensed producer, yet still carry pathogens that can cause serious disease.

One of the most important zoonotic risks is brucellosis, a bacterial infection that can affect livestock, wildlife, dogs, horses and people. In humans, brucellosis can cause fever, sweats, fatigue, joint pain, back pain, recurrent illness and, in some cases, long-term complications involving the heart, liver, spleen, nervous system or reproductive system. The CDC lists unpasteurized milk and dairy products as a major exposure route for brucellosis. (CDC)

The key point is simple: raw milk is not made safe by being local, licensed, organic, fresh, grass-fed, carefully handled or “from a farm I trust.” Pasteurization is the proven step that makes milk dramatically safer.

Quick Answer

Yes, raw milk can cause brucellosis if it contains bacteria from the genus Brucella. People can become infected by drinking unpasteurized milk, eating dairy products made from contaminated raw milk, or handling infected animals, aborted fetal tissues, placenta, blood or reproductive fluids. (CDC)

Brucellosis can be difficult to diagnose because early signs often look like a vague flu-like illness. Anyone who develops fever, sweats, fatigue, headache, muscle pain, joint pain or back pain after raw milk exposure should contact a medical doctor and mention the raw milk exposure clearly. (CDC)

What Is Brucellosis?

Brucellosis is a zoonotic bacterial disease caused by Brucella species. Zoonotic means it can spread between animals and people.

Different Brucella species are associated with different animal hosts:

Brucella species	Common host associations	Why it matters
Brucella abortus	Cattle and bison	Can cause abortion in cattle and can infect people, especially through raw milk or infected birth fluids
Brucella melitensis	Goats and sheep	A major cause of human brucellosis globally, often linked with unpasteurized dairy
Brucella suis	Pigs, feral pigs and some wildlife	Important for hunters, pig dogs, abattoir workers and veterinarians in some regions
Brucella canis	Dogs	Causes reproductive disease in dogs and can infect people
Brucella ovis	Sheep	Important in sheep reproductive disease, but not considered a major zoonotic risk

WHO describes brucellosis as a bacterial disease caused by Brucella species that mainly infect cattle, swine, goats, sheep and dogs, with human infection usually linked to contact with infected animals or contaminated animal products. (World Health Organization)

In livestock, brucellosis is a major animal health and trade disease. In people, it is a public health concern because symptoms can be vague, recurrent and long lasting without proper diagnosis and treatment.

How Does Raw Milk Cause Brucellosis?

Milk can become contaminated when a dairy animal is infected with Brucella.

The animal may not always look obviously sick. USDA APHIS notes that infected animals may appear healthy but still harbour and spread infectious bacteria. In cattle and bison, signs are often most obvious in pregnancy, including abortion, weak calves, reduced milk production, poor conception and retained placenta. (USDA APHIS)

Raw milk is milk that has not been pasteurized. CDC explains that raw milk can contain harmful germs and that farm practices can reduce contamination but cannot guarantee safety. CDC also states that raw milk can expose people to pathogens including Campylobacter, E. coli, Listeria, Brucella and Salmonella. (CDC)

This is why “the farm is clean” is not enough.

A clean farm reduces risk.

Pasteurization controls risk.

Those are not the same thing.

Why Pasteurization Matters

Pasteurization is the process of heating milk to a specific temperature for a specific time to kill disease-causing germs.

FDA states that pasteurization kills harmful organisms responsible for diseases including listeriosis, typhoid fever, tuberculosis, diphtheria, Q fever and brucellosis. FDA also states that pasteurization does not reduce milk’s nutritional value and does not cause lactose intolerance or milk allergy. (U.S. Food and Drug Administration)

The CDC’s current raw milk guidance is blunt: choosing pasteurized milk and dairy products is the best way to safely enjoy milk’s nutritional benefits. (CDC)

That is the part that gets lost in the online argument.

The question is not whether milk is nutritious.

Milk can be nutritious.

The question is whether you want that nutrition with or without preventable bacterial risk.

Pasteurization lets you keep the nutrition while removing a major safety hazard.

Does Licensed Raw Milk Mean Safe Milk?

No.

A license, inspection program or clean reputation may reduce some risks, but it cannot guarantee that every batch is pathogen-free.

A documented Texas case shows why. In 2017, Texas DSHS investigated a human brucellosis case linked to raw cow’s milk from K-Bar Dairy, a licensed raw milk dairy in Paradise, Texas. CDC later reported that raw milk from that dairy tested positive for Brucella abortus vaccine strain RB51, and people who consumed raw milk from the dairy during the exposure period were advised to seek medical care and receive antibiotics to reduce the risk of chronic infection. (Texas Health Services)

CDC’s MMWR report described this as the first documented instance of human brucellosis caused by RB51 through consumption of raw milk acquired in the United States. It also noted that raw milk sales from that farm were legal under Texas rules with a “Grade A Raw for Retail” license. (CDC)

That is the critical lesson:

Legal does not mean risk-free. Licensed does not mean sterile. Raw does not mean safe.

What Are the Symptoms of Brucellosis in People?

Brucellosis can be hard to recognise because early symptoms can look like many other illnesses.

CDC lists early symptoms including:

• Fever
• Fatigue
• Sweating
• Headache
• Muscle pain
• Joint pain
• Back pain
• Loss of appetite
• General malaise

Some symptoms can continue or come and go until treatment is given, including recurrent fevers, arthritis, testicular or scrotal swelling, endocarditis, memory problems, confusion, irritability, depression and swelling of the liver or spleen. (CDC)

The classic name “undulant fever” comes from the way fever can rise, fall and return in waves.

In practice, this is what makes brucellosis dangerous: it may not look dramatic at first. A person may feel vaguely unwell for weeks, and unless someone asks about raw dairy, animal births, hunting, feral pigs, laboratory exposure or veterinary work, the diagnosis can be missed.

Brucellosis Risk Framework

Risk level	What it looks like	What it may mean	What to do
Low risk	Consumed pasteurized dairy only, no animal fluid exposure, no symptoms	Brucellosis risk from dairy is very low	Continue choosing pasteurized products
Moderate risk	Consumed raw milk or raw cheese but currently well	Exposure may have occurred even without symptoms	Stop raw dairy and monitor for fever, sweats, fatigue, muscle pain or joint pain
High risk	Raw milk exposure plus fever, sweats, fatigue, headache, back pain or joint pain	Brucellosis or another raw milk-associated infection is possible	Contact a medical doctor and clearly mention raw milk exposure
Critical	Fever plus pregnancy, immune compromise, severe weakness, confusion, chest pain, severe headache, neurologic signs or persistent symptoms	Serious infection or complications possible	Seek urgent medical care immediately

The key decision point is simple: raw milk exposure changes the medical history. If you become unwell after raw dairy, tell the doctor exactly what you consumed and when.

When Is This an Emergency?

Seek urgent medical care if you or someone in your household develops symptoms after raw milk exposure and any of the following apply:

• Pregnancy
• Weakened immune system
• Infant, young child or older adult
• High or persistent fever
• Severe headache
• Confusion, memory changes or altered behaviour
• Neck stiffness
• Chest pain
• Shortness of breath
• Severe back pain
• Severe joint swelling
• Testicular swelling or pain
• Symptoms lasting more than a few days
• Recurrent fevers or night sweats
• Known exposure to raw milk linked to a public health warning

CDC advises people who think they have been exposed to brucellosis to contact a healthcare provider, and states that untreated brucellosis can become chronic and lead to long-term disease including arthritis, endocarditis, chronic fatigue, depression and liver or spleen swelling. (CDC)

This is not a “detox it out” situation.

This is a bacterial infection that needs proper medical diagnosis and antibiotics.

How Is Brucellosis Diagnosed in People?

Brucellosis diagnosis usually involves laboratory testing.

Tests may include:

• Blood culture
• Bone marrow or other body fluid culture in selected cases
• Serology or antibody testing
• PCR in some settings
• Repeat testing if symptoms persist and early results are unclear

Texas DSHS notes that laboratory diagnosis involves testing samples such as blood, bone marrow or other body fluids. DSHS also warns that brucellosis can be difficult to diagnose without specific testing because symptoms are broad and may wax and wane over weeks or months. (Texas Health Services)

One special issue is Brucella abortus RB51, the vaccine strain involved in the documented Texas raw milk case. CDC notes that RB51 does not stimulate an antibody response detectable by routine serological assays and requires culture for confirmation. RB51 is also resistant to rifampin, which is commonly used in standard brucellosis treatment. (CDC)

That means the exact exposure history matters. A doctor needs to know if raw milk was consumed because it can change which tests and antibiotics are considered.

How Is Brucellosis Treated?

Brucellosis requires antibiotic treatment, usually for several weeks.

CDC states that treatment begins once brucellosis is confirmed and that antibiotics are needed for a minimum of 6 to 8 weeks. CDC also notes that recovery may take weeks to months depending on the timing of treatment and severity of illness. (CDC)

WHO lists common adult treatment regimens that include doxycycline with either streptomycin or rifampicin, although pregnancy, children and special exposures require different medical decisions. (World Health Organization)

This is medical care, not veterinary care and not a home remedy situation.

Do not self-treat. Do not use leftover antibiotics. Do not assume the illness will pass because the fever improves for a day.

Brucellosis can relapse or become chronic if it is not treated properly.

What Else Can Raw Milk Spread?

Brucellosis is not the only concern.

Raw milk can carry multiple pathogens, including:

• Brucella
• Salmonella
• E. coli
• Campylobacter
• Listeria
• Cryptosporidium
• Other bacteria or parasites depending on contamination

CDC lists Campylobacter, Cryptosporidium, E. coli, Listeria, Brucella and Salmonella as germs people may be exposed to through raw milk or raw milk products. (CDC)

FDA also states that raw milk can carry dangerous germs such as Salmonella, E. coli, Listeria and Campylobacter, and that these germs can seriously injure anyone who drinks raw milk or eats products made from it. (U.S. Food and Drug Administration)

So even if a raw milk illness is not brucellosis, the risk is still real.

The symptom pattern matters:

• Vomiting and diarrhea may suggest food poisoning from several bacteria
• Fever and sweats may raise concern for brucellosis
• Pregnancy plus raw dairy exposure raises concern for Listeria and other severe infections
• Blood in stool, severe abdominal pain or dehydration needs urgent medical care

What About Pets and Raw Milk?

Feeding raw milk to pets is not a safe workaround.

FDA specifically states that raw milk marketed for pets or animals is not safe for people to drink. The reverse point also matters: raw animal products can create household hygiene risks when pets consume contaminated products and then shed organisms, contaminate bowls, lick people, or develop illness themselves. (U.S. Food and Drug Administration)

Brucellosis in dogs is most commonly associated with Brucella canis, but dogs can occasionally be infected with other Brucella species through exposure to infected production animals. Merck Veterinary Manual describes canine brucellosis as a zoonotic disease and notes that reproductive signs such as infertility, abortion, stillbirth, epididymitis, prostatitis and orchitis are common. (Merck Veterinary Manual)

Practical pet advice:

• Do not feed raw milk to dogs or cats
• Do not allow pets access to aborted livestock tissues or placentas
• Use caution with raw meat from feral pigs or wild game
• Speak to a veterinarian if breeding dogs have infertility, abortion, stillbirths or spinal pain
• Wash bowls and hands carefully after handling animal products

The real concern is not only whether the pet becomes sick. It is whether raw animal products increase avoidable infection risk in the household.

What About Horses?

Horses can develop brucellosis, but it is uncommon in many countries with strong cattle control programs.

In horses, brucellosis is most often associated with fistulous withers or poll evil, which are deep, painful, draining infections or bursitis near the withers or poll. MSD Veterinary Manual states that horses can be infected with Brucella abortus or Brucella suis, and that suppurative bursitis, commonly recognised as fistulous withers or poll evil, is the most common condition associated with equine brucellosis. (MSD Veterinary Manual)

Signs in horses may include:

• Swelling over the withers
• Swelling at the poll
• Pain around the affected area
• Draining tracts or abscesses
• Stiffness
• Reluctance to be saddled or handled
• Rarely, abortion or reproductive signs

MSD notes that brucellosis in horses is rare in the United States because of elimination of the disease in cattle, and that infected horses are unlikely to be a source of disease for other horses, animals or people. (MSD Veterinary Manual)

In Australia, regional risk is different again. Queensland Health states that B. abortus was eradicated from the Australian cattle herd in 1989 and is considered an exotic animal disease in Australia, while B. suis is endemic in feral pigs in Queensland and has been reported in parts of northern Australia and New South Wales. (Queensland Health)

The practical veterinary message: if a horse has chronic draining withers or poll swelling, it needs veterinary assessment. Brucellosis is not the only cause, but it is one of the important rule-outs depending on region, cattle or feral pig exposure and public health requirements.

What About Livestock?

Brucellosis is a major livestock disease because it affects reproduction and herd movement.

In cattle and bison, USDA APHIS lists signs including abortion, weak calves, decreased milk production, weight loss, poor conception, infertility and retained afterbirth. It also emphasises that appearance alone is not enough to detect disease because infected animals can look healthy and still spread bacteria. (USDA APHIS)

Brucellosis spreads through:

• Milk
• Aborted fetuses
• Placental membranes
• Vaginal discharges
• Reproductive fluids
• Direct contact with infected animals
• Contaminated calving areas
• Contaminated equipment

USDA APHIS states that there is no treatment for brucellosis in livestock, and affected herds are managed through quarantine, movement restrictions, investigation and eradication measures. (USDA APHIS)

This is why suspected livestock brucellosis is not just a farm management issue. It is a veterinary and animal health authority issue.

Raw Milk Myth vs Reality

Myth	Reality
“Raw milk is healthier.”	Pasteurized milk provides the same nutritional benefits without the raw milk infection risk. (CDC)
“Pasteurization destroys the nutrition.”	FDA states that pasteurization does not reduce milk’s nutritional value. (U.S. Food and Drug Administration)
“My farm is clean, so the milk is safe.”	Good farm practices reduce contamination but cannot guarantee raw milk safety. (CDC)
“Licensed raw milk is risk-free.”	A documented Texas brucellosis case was linked to a licensed raw milk dairy. (Texas Health Services)
“If I feel fine today, I am fine.”	Brucellosis symptoms can appear later, persist, or come and go without proper treatment. (CDC)
“Raw milk for pets is safer.”	FDA states raw milk marketed for pets and animals is not safe for people to drink. (U.S. Food and Drug Administration)

What Should You Do if You Drank Raw Milk?

If you are well

Stop consuming raw milk and raw milk products.

Check the product label and source. Keep a record of:

• Product name
• Farm or seller
• Date purchased
• Date consumed
• Lot number if available
• Whether anyone else consumed it
• Any symptoms in the household

Monitor for fever, sweats, fatigue, headache, muscle pain, joint pain, back pain, vomiting, diarrhea or abdominal pain.

If you develop symptoms

Contact a medical doctor and clearly say:

“I consumed raw milk or raw dairy products.”

That sentence matters. It changes the differential diagnosis.

CDC advises people who think they have been exposed to brucellosis to contact a healthcare provider. (CDC)

If you are pregnant, immunocompromised, elderly or caring for a young child

Do not wait for symptoms if there has been a known raw milk public health warning or suspected contaminated batch. Seek medical advice promptly.

Children under 5, adults over 65, pregnant people and immunocompromised people are at higher risk of serious illness from raw milk-associated germs. (CDC)

If the raw milk is linked to a recall or health alert

Follow public health instructions exactly.

In the documented Texas RB51 event, CDC advised people who consumed raw milk products from the implicated dairy during the exposure period to seek antibiotics to avoid long-term infection risk. (CDC Archive)

What Should Farmers and Animal Handlers Do?

If brucellosis is suspected in livestock, contact a veterinarian or animal health authority.

Farm-level precautions include:

• Do not consume raw milk from suspect animals
• Isolate suspect animals as directed by veterinary authorities
• Use gloves, eye protection and protective clothing when handling birth fluids, placenta or aborted fetuses
• Do not allow dogs or wildlife to access aborted tissues
• Clean and disinfect calving areas
• Keep accurate animal movement and reproductive records
• Test new animals where required
• Follow regional vaccination and reporting rules

USDA APHIS recommends clean and disinfected calving areas, gloves when handling birthing or abortion tissues, closed herd practices, isolation and testing of new or re-entering animals, and diagnostic workups for exposed or potentially infected animals. (USDA APHIS)

For veterinarians, animal breeders, shelter staff, laboratory workers, hunters and slaughterhouse workers, CDC recognises increased exposure risk through contact with animal tissues, body fluids or samples. (CDC)

Common Mistakes With Raw Milk and Brucellosis

Mistake 1: Assuming “natural” means safe

Natural does not mean pathogen-free. Brucella is natural too. That is not a selling point.

Mistake 2: Trusting appearance, smell or taste

Milk contaminated with dangerous bacteria does not always look, smell or taste abnormal.

Mistake 3: Forgetting to tell the doctor about raw milk

This is a major one. Brucellosis can mimic other illnesses. If the doctor does not know about raw dairy exposure, testing may be delayed.

Mistake 4: Thinking a licensed farm removes all risk

Licensing and inspection reduce risk but cannot guarantee every raw product is safe. The documented Texas RB51 case involved a licensed raw milk dairy. (Texas Health Services)

Mistake 5: Feeding raw milk to children or pregnant people

Children, pregnant people, older adults and immunocompromised people are at higher risk of serious illness from raw milk pathogens. (CDC)

Mistake 6: Using raw milk for pets

Raw milk is not a good health shortcut for pets. It can create avoidable infection risk for animals and the household.

Mistake 7: Treating brucellosis like a short stomach bug

Brucellosis can persist, recur and cause long-term complications without appropriate antibiotics. CDC states treatment is needed for at least 6 to 8 weeks once confirmed. (CDC)

How To Prevent Brucellosis From Raw Milk

The most effective prevention is simple:

Do not drink raw milk or eat dairy products made from unpasteurized milk.

Practical prevention steps:

• Choose pasteurized milk
• Choose cheese, yogurt, ice cream and cream made from pasteurized milk
• Read labels carefully
• Ask directly if dairy products are pasteurized
• Avoid raw milk sold at farms, markets or private groups
• Do not give raw milk to children, pregnant people, elderly people or immunocompromised people
• Do not feed raw milk to pets
• Wear protective equipment when handling animal births or abortions
• Keep livestock health programs current with veterinary advice
• Report suspected brucellosis in animals according to local rules

CDC says that if you are not sure whether a dairy product is pasteurized, do not eat or drink it. (CDC)

That is the cleanest public health answer.

If the label does not say pasteurized, choose something else.

Frequently Asked Questions

Can raw milk really cause brucellosis?

Yes. Raw milk can transmit Brucella if it comes from an infected animal. CDC, Texas DSHS and MMWR have documented a human brucellosis case linked to raw cow’s milk from a licensed Texas raw milk dairy. (Texas Health Services)

Is raw milk ever completely safe?

No raw milk can be guaranteed pathogen-free. CDC states that good farm practices can reduce contamination but cannot guarantee safety from harmful germs, and pasteurized milk provides the same nutritional benefits without the risks of raw milk consumption. (CDC)

What are the first signs of brucellosis in people?

Early signs can include fever, fatigue, sweating, headache, muscle pain, joint pain, back pain, loss of appetite and general malaise. Symptoms can persist or come and go without treatment. (CDC)

Can brucellosis spread from person to person?

Person-to-person transmission is extremely rare according to CDC. Most human infections come from contaminated animal products, direct animal exposure, infected tissues or laboratory exposure. (CDC)

Does pasteurization reduce milk nutrition?

FDA states that pasteurization does not reduce milk’s nutritional value. Pasteurization kills harmful germs and is one of the most important reasons milk-borne diseases, including brucellosis, have become far less common in places with strong dairy safety systems. (U.S. Food and Drug Administration)

The Bottom Line

Raw milk is not safer because it sounds natural.

It is riskier because it skips the step designed to kill dangerous germs.

Brucellosis is not the most common raw milk infection, but it is one of the most important because it can be hard to diagnose, persist for weeks or months, and cause serious long-term complications without appropriate treatment.

The safest advice is clear:

Do not drink raw milk.

Do not feed raw milk to pets.

Do not give raw milk to children, pregnant people, older adults or immunocompromised people.

If you have consumed raw milk and develop fever, sweats, fatigue, joint pain, back pain, headache, vomiting, diarrhea or ongoing vague illness, contact a medical doctor and mention the raw milk exposure clearly.

Pasteurization is not the enemy of good milk.

It is the reason milk became much safer to drink.

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If you are unsure whether an animal illness, raw milk exposure, abortion event, fistulous withers, reproductive disease or possible zoonotic risk needs urgent action, ASK A VET™ can help you organise the history, identify the right veterinary concerns and decide when medical or veterinary care should not wait.