Glanders: Symptoms, Causes and Zoonotic Risk

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The Forgotten Stable Phantom That Refused to Stay in the Barn

Picture this;

An old horse stable just before sunrise.
The air smells of fresh hay. A groom hums while filling buckets. Horses stamp their hooves impatiently, ready for breakfast.

Then someone notices it.

One horse has thick, sticky discharge trickling from its nose. Another has strange lumps beneath its skin. A third seems unusually tired, despite having been perfectly healthy only days ago.

At first, everyone shrugs.

"Probably just a cold."

But within weeks, more horses fall ill.
Some die.
A few caretakers begin coughing and developing painful sores of their own.

Suddenly, the peaceful stable has become the stage for a medical mystery.

Our villain has arrived.

Its name?

Glanders.

And unlike many forgotten diseases, this one still knows how to make an entrance.

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What It Is

Glanders is caused by Burkholderia mallei, a Gram-negative, rod-shaped bacterium.

Now, bacteria are tiny single-celled organisms. Many are harmless, even helpful. Some help digest your food, while others quietly live on your skin without causing trouble.

But Burkholderia mallei belongs to a much less friendly crowd.

Think of it as a stealthy saboteur.

Instead of crashing through the front door, it quietly sneaks into the body, hides from the immune system, and begins building tiny pockets of infection in different organs.

What I mean to say is, it is a tissue-destroying germ that multiplies in the blood and lungs of its host.

Its favorite victims are horses, donkeys, and mules, but humans can occasionally become accidental targets too.

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What It Does and Why Pet Parents Should Care

Now, here is where it's somewhat interesting.

Glanders may be famous for haunting horses, donkeys, and mules, but under the right (or rather, wrong) circumstances, it can also knock on the doors of dogs, cats, and even humans.

Thankfully, for the average pet parent, this isn't a disease you're likely to bump into on your morning dog walk. In many parts of the world, including North America, Western Europe, and Australia, glanders has been successfully eradicated through decades of strict surveillance and animal health programs.

But in parts of Africa, Asia, the Middle East, and Central and South America, the old stable phantom still lingers.

So, what does it actually do?

Let's follow its wicked little game plan.

Step 1: Entering the Body

Every adventure begins with an entrance.
Burkholderia mallei usually sneaks into the body through one of three routes:

• Breathing in infected droplets or dust.
• Eating contaminated food or water (or, in rare cases, raw horse meat contaminated with the bacterium).
• Slipping through cuts, scrapes, or the moist surfaces of the eyes, nose, or mouth.

The bacterium has officially crossed the drawbridge.

Step 2: Crossing the Body's Protective Barrier

Once inside, the bacterium doesn't stay on the surface for long.
It latches onto the delicate lining of the nose, throat, lungs, or digestive tract, then squeezes between the cells like a burglar slipping through a half-open window.
Soon, it's no longer on the outside.
It's deep inside the body's tissues.

Step 3: Outsmarting the Immune System

Now comes the clever part.

Normally, your body's first responders, special white blood cells called macrophages, rush in to gobble up invading germs.

Mission accomplished?
Not this time.

When a macrophage swallows Burkholderia mallei, it traps the bacterium inside a tiny bubble called a phagosome. Think of it as a microscopic jail cell, where digestive enzymes are supposed to move in and finish the job.
But this burglar came prepared.

Instead of sitting quietly behind bars, Burkholderia mallei pulls out one of its favourite escape gadgets, a microscopic molecular syringe known as the Type III Secretion System (TTSS).
Using this tiny syringe, the bacterium injects special proteins directly into the macrophage, essentially sabotaging the cell from the inside.

First, those proteins help the bacterium break out of its phagosomal prison before the cell's digestive enzymes can destroy it.
Freedom achieved.

Next, it performs an even bolder trick.
Once free inside the macrophage, it hijacks actin, the protein that forms the cell's internal framework and helps it move. Using one of its own proteins, called BimA, it builds "actin comet tails" behind itself. These microscopic structures generate enough force to propel the bacterium through the cell and into neighbouring cells, allowing it to spread while staying largely hidden from the immune system.

And just when you think the macrophage might call for backup...
Burkholderia mallei interferes with the cell's alarm system too.

Normally, infected cells release chemical distress signals called cytokines, alerting the rest of the immune system that trouble has arrived.
The bacterium turns down that alarm.

The result?
It stays hidden.
It multiplies.
And it hitchhikes safely inside the very immune cells that were sent to destroy it.

Imagine calling the police to arrest a burglar...
Only for the burglar to escape the patrol car, disable the police radio, steal the vehicle, and quietly drive through the city wearing the officer's uniform.

That's exactly the kind of trick Burkholderia mallei loves.
And that's what makes glanders such a formidable opponent.

Step 4: Spreading Through the Lymphatic System

Those infected immune cells naturally travel through the lymphatic system, the body's network of tiny drainage vessels and lymph nodes. 
Unfortunately, they're now carrying an unwanted passenger. 
When they reach the lymph nodes, the bacteria begin multiplying, causing the nodes to swell, become inflamed, and, in severe cases, start breaking down.

The villain has officially left the neighborhood and entered the motorway.

Step 5: Invading the Bloodstream

Eventually, the bacteria escape into the bloodstream.
Now they can travel almost anywhere.

• The lungs.
• The liver.
• The spleen.
• The skin.
• Even deeper organs.

This stage is known as septicemia, or blood poisoning, and it's where glanders can become especially dangerous or life-threatening.

What started as a local break-in has become a full-scale invasion.

Step 6: Forming Painful Nodules

By now, the immune system realizes something is terribly wrong.

Its usual strategy, sending white blood cells to gobble up invading bacteria, has completely failed.
Instead of trying to hunt down each bacterium one by one, it decides to lock the whole problem inside a living prison.

Layers of immune cells surround the infected area, building small, firm lumps called granulomas (also known as nodules). Think of them as emergency containment chambers, designed to stop the bacteria from spreading any farther.
It's a clever idea...

But remember it's trick?
The bacteria aren't prisoners inside the granuloma; they're hiding inside the very immune cells that built it. Tucked away within these cells, they're protected from many antibodies and much of the body's defenses, allowing them to continue multiplying in secret.

As more and more immune cells crowd around the nodule, another problem appears.

The centre becomes so tightly packed that oxygen and nutrients can no longer reach it.
Slowly, the tissue in the middle begins to die.
It breaks down into a thick, yellow, cheese-like mixture of dead cells, immune debris, and living bacteria. Pus.

Instead of becoming the bacterium's tomb...
the granuloma becomes its bunker.
A place where the enemy survives while the battlefield around it crumbles.

Step 7: Ulcers Begin to Form

As the infected nodules grow larger, they eventually lose their blood supply and rupture.

• Inside the nose, they leave deep ulcers and produce the thick, sticky nasal discharge that has become one of glanders' signature clues.
• In the skin, painful nodules burst through the surface, leaking infectious pus and leaving slow-healing sores.
• The nearby lymph vessels can become swollen and hard, forming rope-like cords once known as "farcy pipes."

At this point, the bacterium has left its fingerprints everywhere.

Step 8: Organ Damage and Systemic Disease

If the infection isn't stopped, the body's organs begin struggling under the constant attack.

• In fast-moving cases, severe pneumonia, septic shock, and multiple organ failure can develop within days.
• In slower, chronic infections, affected animals may gradually lose weight, become weaker, and suffer progressive damage to their lungs and other organs over weeks or months.

Without timely diagnosis and appropriate treatment in people, or strict disease control in animals, the outcome can be devastating.

What does glanders look like in animals?

In horses, donkeys, and mules, you might notice:

• Thick yellowish or greenish nasal discharge
• Deep ulcers inside the nose
• Swollen lymph nodes beneath the jaw
• Fever
• Persistent cough or difficulty breathing
• Weight loss and poor performance
• Painful skin nodules that may rupture and leak pus

Some animals become desperately ill within days.

Others appear fairly healthy while quietly carrying the infection for weeks or even months, unknowingly putting nearby animals at risk.

Dogs and cats are infected far less often, but when they are, the disease can be severe. They may develop fever, breathing problems, swollen lymph nodes, skin ulcers, and widespread infection throughout the body.

One important risk factor for pets is eating contaminated raw horse meat from regions where glanders still exists, or via close contact with sick horses, donkeys, or mules, especially if infectious fluids enter a cut or splash into the eyes, nose, or mouth.
That's one reason veterinarians encourage careful sourcing of raw diets.

Now, in case you didn't catch it earlier, glanders doesn't always look the same. As you've probably noticed from the pathogenesis above, the disease can manifest in different parts of the body depending on where Burkholderia mallei first establishes infection and how far it spreads. These distinct presentations are known as the clinical forms of glanders, and they are classified as follows:

The Four Faces of Glanders

1. Nasal Glanders

This is the form most people think of when they hear "glanders."
It mainly attacks the nose and upper respiratory tract.

Infected animals develop painful nodules inside the nasal passages that eventually break down into deep ulcers. Thick, yellowish-green nasal discharge becomes one of the disease's most recognizable signs. As the ulcers heal, they often leave behind distinctive star-shaped scars inside the nose.

Oral mucosa. Chronic star-shaped healed lesions

2. Pulmonary Glanders

Sometimes the bacterium travels deeper into the respiratory system and settles in the lungs.
There, it forms nodules and abscesses that make breathing increasingly difficult.
Affected animals may develop a persistent cough, fever, respiratory distress, and gradual weight loss as the lungs struggle to do their job.

3. Cutaneous Glanders (Farcy)

When the infection spreads through the skin and lymphatic vessels, it's traditionally known as farcy.

Firm nodules develop beneath the skin, usually along the legs, chest, or abdomen. Over time, these nodules burst open, forming painful ulcers that discharge thick, infectious pus.

The swollen lymphatic vessels often become enlarged and hardened, creating rope-like cords beneath the skin, an appearance that gave rise to the old term "farcy pipes."

4. Septicemic Glanders 

This is the bacterium's most aggressive move.

Instead of staying in one area, Burkholderia mallei breaks into the bloodstream, allowing it to spread rapidly throughout the body.

Multiple organs - including the lungs, liver, and spleen, can become infected in a short time. Animals often develop high fever, severe weakness, muscle pain, and overwhelming blood infection (septicemia).

Without prompt treatment in humans, or rapid control measures in animals, this form can be fatal.

One Disease, Four Different Faces

Although these forms look quite different, they're all caused by the same bacterium.

Some animals show only one form, while others develop a combination of two or more as the infection progresses.

It's one more reason why veterinarians don't rely on a single symptom. We piece together every clue to uncover the real culprit hiding beneath the surface.

Can people catch it?

Yes.

In people, symptoms often begin like an ordinary flu: with fever, chills, muscle aches, and exhaustion, but can rapidly progress to pneumonia, painful skin ulcers, abscesses, bloodstream infection (septicemia), and damage to multiple organs.

Without prompt medical treatment, glanders can be life-threatening.

Who's most at risk?

Fortunately, this isn't a disease most families encounter in everyday life.

Those at greatest risk include:

• Veterinarians
• Horse owners
• Stable workers
• Animal handlers
• Laboratory personnel
• Military or police units working with horses
• People who regularly work with horses, donkeys, or mules in countries where glanders still occurs

For everyone else, the risk remains very low.
But awareness is powerful.

Why Pet Parents Should Care?

Fair question.

The good news is that most pet owners will never encounter glanders, especially in countries where the disease has been eradicated.

But, as discussed earlier, it occurs exceptionally rarely in domestic pets. Cats are slightly more susceptible than dogs, but feline cases are still categorized as uncommon.

So why should you care?

Because although glanders is rare, it doesn't play around.

It's a serious zoonotic disease with no licensed vaccine for either animals or humans. Once Burkholderia mallei gains a foothold, it's notoriously difficult to eliminate completely.

That's why, in countries with glanders-control or eradication programs, infected animals are generally not treated. Instead, humane euthanasia is usually required to stop the bacterium from spreading to other animals and to people. It's one of the hardest decisions a pet owner can face, but it's made in the interest of protecting public health.

For people who become infected, treatment typically involves weeks of carefully selected antibiotics and close medical supervision. Even after recovery, infection doesn't appear to provide lifelong immunity, meaning it's possible to become infected again after future exposure.

In other words, glanders isn't just a disease that threatens animal health; it can leave both emotional and physical scars. 

That's why we as veterinarians place such a strong emphasis on prevention, early detection, and keeping this centuries-old bacterial villain firmly under control.

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The Discovery

Let's go back to 2,000 years ago.

The First Clues: When Horses Began Telling the Story

In ancient Greece, around the 4th century (450 - 425) BC.

Horses weren't just beloved animals; they were the engines of civilization. They pulled chariots, carried soldiers into battle, ploughed fields, transported goods across kingdoms, and connected entire societies. Losing a healthy horse wasn't just an inconvenience; it could mean losing a livelihood, a harvest, or even a war.

Then came a disease no one could explain.

Handlers watched healthy horses suddenly develop thick, foul-smelling yellowish-green discharge streaming from their nostrils. Painful ulcers formed inside the nose. Swollen lumps appeared beneath the skin, some eventually bursting open and draining pus. Donkeys and mules often died within days, while many horses lingered for months, slowly wasting away.

It was one of the earliest recorded "horse plagues" in history.

Hippocrates Records the First Medical Description

The first known written account came from Hippocrates (c. 460–370 BC), often called the Father of Medicine.

Although he had no idea that bacteria existed, Hippocrates carefully documented the disease's distinctive clinical signs in horses. His observations are considered the earliest surviving medical description of what we now know as glanders.

At the time, diseases were explained using theories such as imbalances of the body's "humors." The true cause remained completely hidden from human eyes.

Aristotle Recognizes a Disease That Could Cross Species

A few decades later, another famous Greek thinker added an important piece to the puzzle.

Aristotle (384 - 322 BC) observed that certain animal diseases could also affect humans, a remarkably advanced idea for his era.

He referred to this devastating horse disease as "melis," meaning "severe disease." Over time, the name evolved into the Latin term malleus, from which the bacterium's species name, mallei, is ultimately derived.

While Aristotle couldn't identify the microscopic culprit, he correctly recognized that the disease did not always stop with animals, a concept we now describe as zoonotic transmission.

The Romans Introduce One of History's First Animal Quarantines

By the 4th and 5th centuries AD, Roman veterinarians had begun noticing something else.

The disease spread from horse to horse.

The military writer and veterinary author Vegetius became one of the first people to clearly describe glanders as a contagious disease. Rather than keeping sick horses with healthy ones, he recommended separating infected animals to slow its spread.

It may sound like common sense today, but at the time it was revolutionary.

These recommendations represent one of the earliest recorded examples of animal quarantine, a practice that remains one of the most powerful tools in modern veterinary medicine.

Glanders and Farcy: Two Diseases... or One?

For nearly two thousand years, veterinarians believed they were dealing with two completely different illnesses.

• The first was glanders, which mainly affected the nose, lungs, and respiratory tract.
• The second was farcy, a disease marked by painful skin nodules and thickened lymphatic vessels that eventually burst through the skin.

Because the symptoms looked so different, they were treated as separate conditions.

That changed in 1797, when Danish veterinarian Erik Viborg performed careful transmission experiments. By studying infected animals, he demonstrated that glanders and farcy were simply different forms of the same disease, caused by the same infectious agent.

It was a landmark discovery that transformed veterinary understanding of the illness.

The Bacterial Culprit Is Finally Revealed

The biggest breakthrough came during the Golden Age of Microbiology in the late nineteenth century.

In 1882, German bacteriologists Friedrich Löffler and Wilhelm Schütz successfully isolated and grew the disease-causing bacterium from the liver and spleen of an infected horse.

For the first time, scientists could point to the exact culprit responsible for centuries of devastation.

They named it Bacillus mallei. As bacterial classification improved over the following decades, it was reclassified under its modern scientific name: Burkholderia mallei.

After more than 2,300 years of observation, speculation, and careful investigation, the mystery had finally been solved.

Its discovery spans more than two millennia, making it one of the longest scientific investigations in the history of infectious diseases.

It's a powerful reminder that every breakthrough in veterinary medicine begins with careful observation, relentless curiosity, and generations of people refusing to stop asking one simple question:

"What's making these animals sick?"

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The Naming Story

The word "glanders" comes from the Old French glandres and the Middle English glaundres, both meaning "glands."

That makes sense because one of the disease's classic signs is the dramatic swelling of the lymph nodes beneath a horse's jaw.
These swollen glands often became so noticeable that they helped veterinarians recognize the illness long before microscopes entered the picture.

The name simply stuck.
But that's only part of the story.

Back in Ancient Greece, Aristotle called the disease melis, meaning "severe disease."

As Greek medicine flowed into the Roman world, melis gradually evolved into the Latin word malleus, meaning "hammer."
Because when this disease struck a stable, it hit like one.

Then came farcy.
When the infection showed up mainly as painful skin ulcers and swollen, rope-like lymph vessels, people assumed it was an entirely different disease. So they gave it a different name. 
Farcy comes from the Latin farcire, meaning "to stuff or cram," which describes the thick, swollen cords beneath the skin.

When German bacteriologists Friedrich Löffler and Wilhelm Schütz isolated the bacterium in 1882, they named it Bacillus mallei, borrowing from the old Latin name. Today, it's known as Burkholderia mallei, honouring American plant pathologist Walter H. Burkholder, after the bacterium was later reclassified into the Burkholderia genus.

Sometimes, history names diseases after places.
Sometimes after scientists.
This one simply pointed to one of its most obvious calling cards.

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How It Spreads

Unlike mosquitoes that act as tiny flying chauffeurs, Burkholderia mallei prefers much simpler transportation.

Animal to Animal

The bacterium spreads through:

• Nasal secretions
• Saliva
• Pus from skin lesions
• Shared water buckets
• Feed troughs
• Contaminated equipment
• Close contact

One infected horse can unknowingly expose many others in a busy stable.

Animal to Human

People usually become infected when infectious fluids enter:

• Cuts
• Scratches
• Eyes
• Nose
• Mouth

Breathing contaminated droplets during close handling is another possible route.

Human to Human

Here's some reassuring news.

Natural person-to-person spread is considered extremely rare and has not played a meaningful role in outbreaks.

In other words, this is a disease that prefers staying close to its animal hosts.

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Death Toll and Global Impact

Although glanders has never caused a global pandemic, its impact has been enormous wherever it appears.

Death Toll

Throughout history, glanders has earned a grim reputation as one of the deadliest bacterial diseases affecting both animals and humans.

Humans

Model of the head of a person infected with glanders by Patrick Landmann

In people, the outlook before the antibiotic era was devastating. Untreated glanders carries a case - fatality rate of approximately >90%, particularly in the septicemic (bloodstream) and pulmonary (lung) forms. Many patients died within 7 to 10 days of developing severe disease, while those with overwhelming septicemia could succumb in as little as 24 to 48 hours after septic shock developed. Even with modern antibiotic therapy, the mortality rate remains high, ranging from 40% to 50%, depending on the severity and form of the disease.

Equids

The disease is equally devastating in equids. Donkeys and mules are the most susceptible, with acute infections carrying a natural mortality rate approaching 90 - 100%, often resulting in death within 1 - 2 weeks. Horses usually develop a more chronic form of the disease, surviving for months or even years before eventually dying if left untreated. However, because glanders is a legally notifiable disease in most countries, infected horses are almost always euthanized after diagnosis to prevent further spread. As a result, the practical mortality rate for confirmed animal cases is effectively 100%, whether from the disease itself or compulsory culling.

Companion animals

Companion animals are only rarely affected by glanders, but the outcome is almost always fatal. Cats are highly susceptible and typically develop a rapidly progressive disease characterized by septicemia, severe pneumonia, and widespread skin lesions. Untreated infections have a mortality rate approaching 100%, with death often occurring within just a few days of the onset of clinical signs. Dogs are naturally much more resistant and only rarely develop clinical disease. 

However, because glanders is a legally notifiable disease and poses a serious zoonotic risk, any confirmed infection in either cats or dogs is generally managed by compulsory euthanasia rather than treatment. Consequently, the practical mortality rate for confirmed cases in companion animals is effectively 100%, whether due to the disease itself or mandatory culling.

Public Health Impact

Although human glanders is uncommon today, it remains one of the most significant zoonotic bacterial diseases because of its ability to infect people who work closely with equids or the bacterium itself.

The disease poses a particular occupational risk to veterinarians, horse owners, stable workers, abattoir personnel, military staff, animal handlers, and laboratory scientists. Human infection can cause severe illness affecting multiple organ systems, including the lungs, bloodstream, skin, and internal organs. Because its symptoms often resemble diseases such as tuberculosis, melioidosis, or typhoid fever, diagnosis can be difficult, delaying appropriate medical care.

Even a single confirmed human case typically requires extensive public health investigations, including laboratory confirmation, exposure assessments, and monitoring of people who may have come into contact with the infected individual or animal. As a result, glanders places considerable demands on healthcare and public health resources despite its rarity.

Animal Health Impact

Glanders primarily affects horses, donkeys, and mules, but its impact extends far beyond these species.

Infected animals often develop chronic respiratory disease, skin lesions, nasal ulcers, and progressive weight loss that reduce their strength, endurance, and overall performance. Working animals may become unable to pull carts, plough fields, transport goods, or perform military and police duties.

Some horses develop chronic infections while continuing to shed Burkholderia mallei, allowing the disease to spread silently through equine populations before obvious clinical signs appear.

Although equids are the principal hosts, glanders has also been reported in other mammals, including goats, dogs, domestic cats, camels, and zoo carnivores. A notable example occurred in 2010, when infected horse meat fed to captive animals at Tehran Zoo resulted in the deaths of four African lions and one Siberian tiger, illustrating the bacterium's ability to affect diverse animal species.

Agricultural Impact

For centuries, horses, donkeys, and mules formed the backbone of agriculture in many parts of the world.

These animals ploughed fields, transported harvested crops, carried irrigation supplies, hauled farming equipment, and connected rural communities with local markets. When glanders affected large numbers of working equids, agricultural productivity declined because farmers lost much of their available draft power.

The disease also disrupted routine farm activities by contaminating shared stables, watering points, harnesses, and equipment, making daily agricultural operations increasingly difficult and reducing overall farm efficiency.

Livestock Industry Impact

Glanders has long been one of the most damaging infectious diseases affecting the equine industry.

The disease reduces the health, productivity, and economic value of horses, donkeys, and mules used for breeding, racing, recreation, agriculture, transport, and security services. Chronic infections can severely limit an animal's ability to work or reproduce, while silent bacterial shedding allows infection to spread within stables and equine facilities.

Because equids play important economic and cultural roles in many countries, outbreaks can affect breeders, trainers, riding schools, transport operators, and communities that depend on healthy horse populations.

Economic Impact

The economic effects of glanders extend far beyond infected animals.

Outbreaks disrupt businesses that depend on horses and other equids, including breeding farms, racing industries, tourism, recreational riding, transport services, and agriculture. Farmers and owners may lose years of investment in valuable breeding stock, working animals, or elite performance horses.

Governments and veterinary authorities also face substantial financial burdens associated with disease investigations, laboratory diagnostics, surveillance activities, epidemiological tracing, movement restrictions, and emergency response operations. Collectively, these disruptions can have significant economic consequences for both local communities and national livestock sectors.

Transportation Impact

Before the advent of motorized transport, horses, donkeys, and mules were the engines of commerce.

They carried passengers, delivered mail, transported food, moved military supplies, and hauled commercial goods across towns, cities, and rural landscapes.

When glanders spread through equine populations, transport networks slowed considerably. Rural communities became more isolated, commercial deliveries were delayed, agricultural products struggled to reach markets, and the movement of essential supplies became increasingly difficult. In many regions, widespread outbreaks disrupted entire transportation systems that depended almost entirely on animal power.

Military Impact

Few animal diseases have influenced military operations as profoundly as glanders.

Throughout history, armies relied on horses and mules for cavalry, artillery transport, reconnaissance, medical evacuation, and the movement of food, weapons, and supplies. Disease outbreaks reduced the availability and effectiveness of these animals, weakening military mobility and logistical support.

Its strategic importance became particularly evident during the American Civil War and World War I, when glanders significantly affected military horse populations. The disease was even deliberately spread against enemy transport animals, demonstrating how disabling military logistics could alter the course of military campaigns.

International Trade Impact

Because glanders remains a disease of international concern, its detection can have immediate consequences for global trade.

Countries affected by outbreaks may face restrictions on the movement of live horses, donkeys, mules, semen, embryos, and other equine biological materials. International equestrian competitions, horse racing events, breeding programmes, and animal exports may also be disrupted.

For nations with active equine industries, these trade limitations can reduce market access, delay international movement, and affect businesses that depend on cross-border trade.

Social Impact

The effects of glanders extend beyond animal health to the people and communities that depend on equids.

For many rural families, horses and donkeys represent transportation, farming power, income, and financial security. When these animals become unavailable, daily activities, livelihoods, and local economies can be severely disrupted.

Outbreaks may also generate public anxiety, particularly in communities where equids play an essential role in work or culture. The loss of trusted working animals often carries a significant emotional burden alongside the practical and economic consequences.

Veterinary and Public Health Impact

Glanders has played an important role in shaping modern veterinary medicine and the One Health concept.

The disease illustrates how closely animal health, human health, and environmental factors are interconnected. Because Burkholderia mallei can infect both animals and humans, effective management requires collaboration among veterinarians, physicians, microbiologists, epidemiologists, public health authorities, and laboratory scientists.

Glanders has also advanced veterinary diagnostics and disease surveillance by highlighting the importance of identifying chronically infected carrier animals and improving laboratory methods for detecting zoonotic pathogens.

Biosecurity and National Security Impact

Glanders has importance beyond veterinary medicine because of its potential to affect national security.

The ability of Burkholderia mallei to spread through aerosol exposure and infect both animals and humans has led to its historical investigation and misuse as a biological weapon. As a result, the bacterium is considered a high-priority biosecurity threat in several countries.

Its potential impact extends beyond individual infections. A deliberate release could disrupt agriculture, transportation, trade, military logistics, and public health simultaneously, making glanders a disease of concern for both veterinary authorities and national security agencies.

Historical and Civilizational Impact

Few animal diseases have influenced human civilization as quietly, but as profoundly, as glanders.

Long before tractors, trucks, and mechanized warfare, horses and other equids powered agriculture, transportation, communication, trade, and military campaigns. Wherever these animals were essential, glanders had the potential to slow economic growth, weaken armies, interrupt commerce, and reshape local societies.

The disease has been recognized since antiquity, with descriptions dating back to Aristotle, making it one of the oldest documented infectious diseases of animals. Its history reflects the close relationship between human progress and the health of the animals that helped build civilizations.

Quite the résumé for a microscopic bacterium, isn't it?
One tiny organism managed to unsettle civilizations, empty stables, halt trade, challenge armies, inspire quarantine laws, and remind humanity that sometimes the smallest villains leave the biggest footprints.

But diseases don't spread through biology alone.
They also ripple through politics, economies, and society, influencing how governments respond, how communities react, and sometimes, unfortunately, how people treat one another.
So... what was the world like when glanders was making headlines?
Let's step into the political and social atmosphere of the time.

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Political and Social Atmosphere

Imagine living in the late 1800s or the early decades of the 20th century. Where civilization runs on four legs. Horses, mules, and donkeys, the engines that keep society moving.

When glanders appeared, it threatened far more than the health of a few animals. As discussed in its impacts above.

As political tensions intensified in the early 20th century, especially during World War I, fears surrounding glanders reached an entirely new level. Healthy horses and mules were essential to move artillery, food, ammunition, medical supplies, and troops. A disease affecting transport animals could be almost as damaging as a direct attack on the battlefield.

Those fears proved to be more than wartime paranoia, as evidenced by the deliberate infection of Allied horses and mules in several countries as part of covert biological sabotage campaigns by the Germans. 

The tense climate fueled suspicion toward horse traders, transport workers, livestock dealers, and border inspections.

Fear, however, rarely stops with the disease itself. It often spills over onto the people closest to it. Stable workers, veterinarians, farriers, equine butchers, and animal transporters faced the greatest occupational risk because they handled horses every day. Although these professionals were essential to controlling outbreaks, public anxiety sometimes led people to avoid or distrust them simply because of their work.

Unlike some infectious diseases that have fueled widespread xenophobia against particular ethnic or national groups, glanders was not historically linked to sustained prejudice toward a specific population. Instead, the stigma largely followed occupations associated with infected animals. The fear centered on the possibility of exposure rather than on a person's ethnicity or nationality.

By the late 20th century, many industrialized countries had successfully eliminated glanders. As a result, the disease became increasingly confined to parts of Asia, Africa, the Middle East, and South America.

This success, however, gave rise to a different kind of stigma towards such Countries where glanders remained endemic, resulting in strict trade restrictions, prolonged quarantine requirements, and increased scrutiny in the international movement of horses. While these measures were intended as a control method, they reinforced unfair perceptions that affected regions were inherently "unsafe" or "disease-ridden".

If history teaches us anything, it's this: blaming the stable hand for glanders makes about as much sense as blaming the mail carrier for a bad letter. The real villain was always the bacterium, not the people trying to stop it.

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Actions Taken

Once scientists understood what caused glanders, they developed powerful strategies.

Governments introduced:

• Mandatory reporting
• Laboratory testing
• Movement Restrictions and Travel Controls
• Quarantine measures
• Careful tracing of exposed animals
• Thorough environmental disinfection

Because infected horses can continue spreading the disease, affected animals have often been humanely euthanized to prevent larger outbreaks.
While emotionally difficult, this approach has been highly effective in eliminating glanders from many countries.

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Glanders as a Bioweapon

By now, we know what glanders is, how Burkholderia mallei behaves, and how readily the disease can cross the animal-human boundary. We have also seen why its ability to cause severe disease makes it a serious public health concern. But there is another, darker chapter in its history: biological warfare.

First, what exactly is a bioweapon?

Biological and toxin weapons are microorganisms such as bacteria, viruses, fungi, or toxic substances produced by living organisms that are deliberately developed, weaponized, or released to cause disease, death, or disruption in humans, animals, or plants. Unlike conventional weapons, their effects can spread beyond the original target, creating difficult and potentially large-scale public health challenges.

Glanders is classified as a biothreat agent because B. mallei possesses several characteristics that make it concerning from a biological-warfare perspective. When delivered as an aerosol, the bacterium can infect through the respiratory tract, cause severe pulmonary or systemic disease, and produce very high mortality in untreated cases. There is also no approved human vaccine, while treatment requires prolonged courses of antibiotics and careful medical management. These characteristics make glanders potentially useful as a weapon of disruption, particularly against military forces and the animals they depend upon.

Its significance is not merely theoretical. Glanders has a documented history of deliberate use and investigation as a biological weapon, particularly during the world wars. In some cases, the target was not people directly, but the horses and mules that armies depended upon for transport, cavalry, artillery, and supplies. Infecting these animals could cripple logistics without firing a single conventional weapon.

So, how did glanders move from a naturally occurring disease of working animals to an instrument of biological warfare?

Below are some of the documented and reported cases in which glanders was deliberately used, investigated, or suspected in warfare.

• World War I - German sabotage: German agents, including Anton Dilger, deliberately infected horses and mules intended for Allied forces, using glanders as a form of anti-livestock warfare designed to disrupt military transportation and logistics.
• World War II - Japan's Unit 731: Japanese military researchers at the Píngfáng complex in occupied China used B. mallei in biological-warfare research and deliberately infected animals and human prisoners, making glanders part of some of the most disturbing biological experiments of the era.
• Soviet-Afghan War - (1982 - 1984): Soviet use of glanders against Afghan resistance forces and their transport animals has been reported and alleged, but the evidence is less firmly established than the documented historical cases above.
• The USAMRIID case - 2000: A microbiologist working at the U.S. Army Medical Research Institute of Infectious Diseases developed laboratory-acquired pulmonary and cutaneous glanders. Although this was an accidental occupational infection rather than a weapons attack, the case demonstrated the continuing hazards associated with handling B. mallei and its relevance to biodefense preparedness.

Now that we know glanders has been used in military warfare and has potential as a biological weapon, what about naturally occurring outbreaks? Has glanders ever caused significant outbreaks among animals or people?

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A History of Natural Outbreaks

From everything we’ve uncovered so far, one thing is clear: this ancient disease hasn’t disappeared and remains endemic or continues to re-emerge in parts of Asia, the Middle East, South America, and Africa, quietly resurfacing wherever susceptible equids, environmental conditions, and opportunities for transmission line up.

So, it’s time to follow the trail.

Year(s)	Location (Country, Region)	Species Affected	Cases (Animals, Humans)	Deaths (Animals, Humans)	Notes & References
2006	India (Maharashtra)	Equids (horses, ponies)	23 seropositive	–	First major post-eradication outbreak; 23 equids tested positive by CFT.
2006–07	India (multiple (6) states)	Equids	117 seropositive	–	Glanders outbreaks occurred across multiple states following the Maharashtra outbreak; surveillance identified 117 seropositive equids during the 2006–07 period.
Oct 2009–Mar 2010	India (Chhattisgarh)	Equids (horses, pony)	13 seropositive	–	New outbreak in Chhattisgarh. Initially, 4 of 63 horses were CFT-positive and B. mallei was isolated from 2 horses. Across the outbreak, 13 equids (12 horses and 1 pony) were CFT-positive among 286 tested.
May 2010	India (Himachal Pradesh)	Mules	4 seropositive; 1 culture-positive	2 deaths	Nasal glanders in Pandoh, Mandi District. Four mules were CFT-positive; two died within a week, and B. mallei was isolated from a nasal swab.
Dec 2010–Jan 2011	India (Uttar Pradesh)	Mules, donkeys, ponies, horses	7 seropositive	–	Glanders recurred in Bijnor and Ghaziabad districts. Three B. mallei isolates were recovered from nasal swabs in Bijnor; 7 of 121 equids tested positive in Ghaziabad.
Apr–Sep 2010	Bahrain (north)	Horses, camel	≈50 horses, 1 camel	–	Glanders outbreak involving horses and a camel; reported as an introduced outbreak.
Jan 2011	Bahrain (same region)	Horses	Re-emergence; exact number not specified	–	Glanders re-emerged in the same region following the 2010 outbreak.
Dec 2010–Jan 2011	Iran (Tehran, Eram Zoo)	African lions, Amur/Siberian tiger	At least 4 lions + 1 tiger confirmed	4 lions + 1 tiger died; ≈14 lions culled	Zoo outbreak; tiger imported from Russia; infection source disputed.
1999–2020	Pakistan (Punjab province)	Equids	Endemic; multiple outbreaks	–	Endemic hotspot; persistent B. mallei lineages linked to equine movement. (isolates 1999–2007)
2015–2018	India (12 states)	Equids	932 seropositive	–	Nationwide surveillance; cases detected in 120 districts, with increasing occurrence and re-emergence in several states.
2019–2023	India (19 states + 3 UTs)	Equids	728 seropositive	–	Nationwide surveillance; cases detected in 138 districts, with a declining seroprevalence from 2019 to 2023.
2017–2018	Brazil (São Paulo & Pernambuco)	Horses	17 (equine cases total)	–	Three outbreaks: Capivari, Tatuí and Garanhuns; 9/17 culture-positive and all 17 PCR-positive.
Nov–Dec 2020	Nepal (Bagmati & Lumbini Provinces)	Equids (horses, mules)	Confirmed cases: 5 equids seropositive, 3 PCR-positive	Several deaths reported; exact total not established	First-ever Nepal outbreak: mules showed more severe disease; strains closely related to those circulating in India.
2019 & 2022	Mongolia (Khan-Uul, Ulaanbaatar)	Horses	4 confirmed	–	Sporadic outbreaks; first molecular characterization of Mongolian B. mallei isolates. All four isolates belonged to the L3B1 cluster, forming a unique Mongolian subbranch.
2024	Brazil (Rio Grande do Norte)	Human	1 confirmed	–	73-year-old man with severe pneumonia; B. mallei confirmed by PCR and genome sequencing. Likely occupational exposure linked to contact with an infected horse.

Sources:

Malik P, Singha H, Khurana SK, Kumar R, Kumar S, Raut AA, Riyesh T, Vaid RK, Virmani N, Singh BK, Pathak SV, Parkale DD, Singh B, Pandey SB, Sharma TR, Chauhan BC, Awasthi V, Jain S, Singh RK. Emergence and re-emergence of glanders in India: a description of outbreaks from 2006 to 2011. Vet Ital. 2012 Apr-Jun;48(2):167-78. PMID: 22718333. Pdf

And there’s the trail. Across decades and borders, these outbreaks tell us one important story: glanders doesn’t have to be everywhere to matter; it only needs an opportunity to move from an infected animal to a susceptible one. The good news is that prevention starts with simple, practical steps. So, let’s step out of the history books and bring the investigation home. Here’s what pet parents and the public can do to help keep animals, families, and communities safer.

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Prevention Tips for Pet Parents & the Public

A. What Pet Parents Can Do

If you own or work with horses:

• Buy animals from reputable sources.
• Isolate new arrivals before introducing them to the herd.
• Never share contaminated grooming equipment.
• Wear gloves when handling suspicious wounds or nasal discharge.
• Wash your hands thoroughly after caring for animals.
• Contact a veterinarian immediately if a horse develops unexplained nasal ulcers, swollen lymph nodes, or persistent discharge.
• Never attempt to treat suspected glanders without veterinary guidance.

For most cat and dog owners, routine hygiene and avoiding contact with sick livestock are usually sufficient.

B. What Vets & Health Professionals Do

Behind the scenes, veterinary teams work tirelessly by:

• Investigating suspicious cases
• Collecting laboratory samples
• Monitoring outbreaks
• Enforcing biosecurity measures
• Educating horse owners
• Reporting cases to animal health authorities
• Coordinating with public health experts when human exposure is possible

This teamwork is a perfect example of the One Health approach, where animal health, human health, and environmental health all work together.

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Treatment and Prognosis

Diagnosing glanders isn't as simple as taking a quick look. Because its clinical signs can resemble several other diseases, veterinarians rely on a combination of diagnostic tools to confirm infection, including:

Veterinarians combine:

• Clinical examination
• Laboratory cultures and bacterial isolation
• Molecular tests such as polymerase chain reaction (PCR)
• Blood tests (serology)

Treatment and prognosis differ vastly between animals and humans due to extreme public health risks, regulatory frameworks, and how the pathogen behaves in different host species.

When it comes to animals, particularly horses, donkeys, and mules. 
The approach to glanders may seem surprising. 
Although Burkholderia mallei is susceptible to certain antibiotics in the laboratory, treating infected animals is generally prohibited in countries with glanders eradication programs because antibiotics often fail to eliminate the bacterium completely. 
It's like painting over rust. It may look better for a while, but the underlying problem continues to spread.
As a result, an apparently recovered animal can remain an asymptomatic carrier, silently shedding the bacteria and infecting other animals or even people. 
To eliminate this ongoing public health risk, international disease-control guidelines require infected equids to be humanely euthanized, with carcasses safely disposed of by incineration or deep burial.

In people, glanders can often be treated successfully if diagnosed early, but treatment is intensive and requires both patience and close medical supervision. 
Patients typically begin with 10 to 14 days of intravenous antibiotics, such as imipenem, meropenem, or ceftazidime, followed by a prolonged course of oral antibiotics, usually 3 to 12 months of trimethoprim-sulfamethoxazole (TMP-SMX) or doxycycline, to eradicate any remaining bacteria and reduce the risk of relapse. 
In more severe cases, deep abscesses that develop in organs such as the liver or spleen may also require surgical drainage in addition to antibiotic therapy.
It's like removing termites from a house; if a few survive, the damage continues.

The prognosis for glanders depends largely on the host species, the form of the disease, and how quickly treatment begins. 

Prognosis in Humans

In humans, the prognosis is generally: 

• Guarded, even with prompt diagnosis and aggressive treatment, because severe pulmonary and septicemic infections still carry a mortality rate of approximately 40% to 50%. 
• Without treatment, the prognosis is grave, with mortality approaching 95%, and many patients dying within 7 to 10 days of developing severe disease. 

Prognosis in Animals

In animals, particularly equids, the prognosis is considered grave, not only because the infection is difficult to eliminate completely, but also because international disease-control policies require infected animals to be humanely euthanized to prevent further transmission.

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Fun Tidbits

Did you know?

1. The villain has a close cousin.
Burkholderia mallei evolved from another bacterium, Burkholderia pseudomallei, which causes melioidosis.

2. Ancient horse doctors noticed glanders long before microscopes existed.
They recognized the swollen glands and nasal ulcers simply by careful observation, a reminder that good veterinary medicine has always started with paying attention.

3. It's one of the oldest known horse diseases in recorded history.
Long before cars, trains, or airplanes, glanders was already challenging horse owners across civilizations.

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Your Turn

And just like that, our stable specter has stepped out of the shadows.

A remarkably stubborn bacterium that spent centuries reminding us why good hygiene, sharp-eyed veterinarians, and a healthy dose of scientific curiosity matter.

The goal here isn't to make you eye every horse with suspicion, refuse every countryside trail ride, or start interrogating donkeys like they're hiding state secrets.

Horses are extraordinary.
Donkeys are hardworking.
Mules are famously dependable.

They've carried explorers across continents, helped build civilizations, worked farms, served in armies, and stolen countless hearts along the way.

Glanders is simply one of the microscopic hitchhikers that occasionally tries to crash the journey.

This episode of The Vet Vortex was created to shine a light on one of veterinary medicine's older, lesser-known mysteries, one that reminds us just how closely human and animal health have always been connected.

So if this story:

• took you on a stroll through history's bustling stables,
• introduced you to one of the oldest bacterial villains known to horse medicine,
• or made you pause and think, "Wait... people can catch diseases from horses too?"

...then don't let the adventure end here.

• Save this post for your next trip down the veterinary rabbit hole.
• Share it with a horse owner, equestrian friend, stable manager, veterinary student, or that one history buff who loves discovering the strange stories hiding behind everyday life.
• And if you've ever owned a horse, worked around stables, or have a fascinating equine tale to tell, trot down to the comments; we'd love to hear it.

And remember...

This blog exists for education, empowerment, and just the right amount of adventure.

But if a horse develops unusual nasal discharge, stubborn skin nodules, unexplained weight loss, or anything that simply doesn't seem right, the next stop shouldn't be another internet search.

It's your veterinarian.
The real-life detective.
The one who knows that every cough, every swollen lymph node, and every mysterious symptom is another clue waiting to be pieced together.

Healthy horses.
Healthy people.
A few more mysteries solved before breakfast.

Until next time,

stay curious, stay informed, and stay wonderfully vortexy.

Check out our previous post: Giardiasis in Humans and Pets.