Soil Fever: The Silent Threat Lurking in Soil and Water—What Animal Owners Need to Know
A veterinary science expert from Chulalongkorn University is urging animal owners to be on alert for Soil Fever (melioidosis), a potentially serious bacterial disease found in soil and water that tends to surge during the rainy season. The disease can affect both humans and animals, with goats and sheep facing the highest risk. Pigs may become infected without showing symptoms but can develop internal abscesses. To reduce the risk, the expert advises against raising livestock in areas with a history of outbreaks and recommends buying meat and milk only from certified, reliable sources.
Although melioidosis may be unfamiliar to many, it is not an emerging disease. Recent figures from Thailand’s Department of Disease Control show that between January 1 and April 18, 2026, the country recorded 752 cases of melioidosis. More than 370 patients required hospital treatment and recuperation, and 23 deaths were reported.
Assistant Dean and Director, Veterinary Student Training Centers,
Faculty of Veterinary Science, Chulalongkorn University
Livestock and pets can also contract melioidosis, although disease surveillance and reporting in animals are not as extensive as they are in the public health sector, said Dr. Rachod Tantilertcharoen, D.V.M., Assistant Dean and Director of Veterinary Student Training Centers, Faculty of Veterinary Science, Chulalongkorn University, in Nakhon Pathom and Saraburi provinces.
“Many farmers remain unaware of the disease, how it is diagnosed, or that cases should be reported. Disease prevention is largely reactive, with samples submitted to veterinary diagnostic laboratories for confirmation only after infection is suspected. We detect cases of melioidosis in animals every year,” said Dr. Rachod, who warned that the risk of melioidosis increases during the rainy season. He urged the public to learn more about the disease and take appropriate precautions to protect themselves, their pets, and livestock from an infection that can be severe and potentially fatal.
The Bacterium Behind Melioidosis
Melioidosis, also known in Thai as Mongklo Thiam or Soil Fever, is caused by the bacterium Burkholderia pseudomallei, which naturally inhabits water and soil.
“This bacterium thrives in the hot, humid climate of Southeast Asia and can survive in the environment for many years. The more humid the conditions, the longer it can persist. It can even survive for extended periods in clean water,” said Dr. Rachod.
Burkholderia pseudomallei thrives in the hot, humid climate of Southeast Asia and can persist in the environment for many years. Dr. Rachod explained that “storms can bring bacteria buried in the soil to the surface. The bacterium can enter the body through three main routes:
- Direct contact with contaminated soil or water through cuts or open wounds
- Consumption of contaminated food or water.
- Inhalation of contaminated dust or water droplets.
“Melioidosis is generally not transmitted directly from one animal to another. However, people can become infected through contact with contaminated secretions or materials from infected animals, as well as through the consumption of contaminated animal products. In both humans and animals, infection most commonly occurs through exposure to contaminated environmental sources, particularly soil and water,” said Dr. Rachod, adding that “the likelihood of an infected person transmitting the bacterium to others is very low. Unlike influenza, which spreads readily from person to person. Transmission between animals is also uncommon.”
Animals Most at Risk of Melioidosis
Animals at highest risk of melioidosis fall into three main groups:
- Highly susceptible animals: Goats and sheep, which often develop severe symptoms. Outbreaks can spread through entire herds and result in high mortality. Common signs include fever, lethargy, loss of appetite, and joint inflammation that causes lameness. Some animals may also exhibit neurological symptoms, such as seizures, as well as respiratory disease and pneumonia.
- Animals that often show no obvious symptoms: pigs, cattle, and buffaloes. These animals may carry the infection without appearing ill. However, the bacterium can cause abscesses in internal organs, including the liver, spleen, and lungs, potentially leading to sepsis and sudden death, especially in pigs, and increasing the risk of contamination in the food chain.
- Animals with lower susceptibility to infection: Dogs and cats are generally more resistant to the bacterium than other animals, but they can still become infected through wounds or cuts in the skin. Signs of melioidosis in dogs and cats may include lethargy, fever, and abscesses in various parts of the body, including subcutaneous abscesses.
Dr. Rachod explained that “When animals that die from melioidosis are not properly disposed of, the bacterium can be released back into the environment and become a source of contamination.
For humans, the risk of melioidosis comes not only from direct exposure to contaminated soil and water but also from consuming contaminated meat, offal, or milk from infected animals.
“People can become infected if an animal carrying the bacterium enters the food chain and the meat is not handled or cooked properly. Without adequate heat treatment to kill the bacteria, anyone who consumes the contaminated meat may be at risk of infection,” said Dr. Rachod.
Treatable with the Right Medication
Melioidosis can be cured in both humans and animals with appropriate antibiotic treatment. The same classes of antibiotics are used in both, including ceftazidime, meropenem, and imipenem, typically administered for two to four weeks. These drugs are most commonly used to treat people and companion animals such as dogs and cats. In livestock, however, treatment decisions are often guided by economic considerations, and infected animals are more commonly culled than treated.
“When livestock develop joint pain, lameness, or die with lesions suggestive of infection, owners or veterinarians should submit samples to a diagnostic laboratory to confirm whether Burkholderia pseudomallei is present. If melioidosis is not specifically suspected and requested, the bacterium may be misidentified as Pseudomonas, a closely related organism. For this reason, veterinarians should clearly request testing for Burkholderia pseudomallei, which is relatively straightforward to culture and diagnose,” said Dr. Rachod. He added that animal owners can have samples tested at the National Institute of Animal Health, regional diagnostic centers operated by the Department of Livestock Development, and veterinary diagnostic laboratories at university faculties of veterinary science across the country.
Failure to submit carcasses for laboratory testing—or to specifically request testing for melioidosis—can lead to inaccurate treatment, delays in outbreak control, and significant underreporting of the disease in livestock.
Heightened Risk of Infection During the Rainy Season
There is currently no vaccine available to prevent melioidosis. Dr. Rachod therefore recommends the following preventive measures for animals, farmers, and consumers:
Livestock
- Avoid raising animals in areas with a history of melioidosis, particularly highly susceptible species such as goats and sheep, to reduce the risk of infection.
- Provide animals with clean drinking water. Keep them away from puddles, other untreated surface water sources, and stagnant water during the dry season. Where possible, drinking water should be treated or sourced from safe supplies such as tap water.
Companion Pets
- Keep dogs and cats indoors during the rainy season, particularly during and after heavy storms, as the bacterium can be more easily dispersed in wet and windy conditions.
Farmers
- Because the bacterium can be shed in milk, caution should be exercised when milking goats and cows. Avoid milking animals if you have cuts or open wounds on your body.
- Wash your hands thoroughly after handling animals.
- When butchering an animal, take care not to rupture any abscesses found in the internal organs, as this can lead to contamination.
- If an animal is suspected to have died from melioidosis, notify local livestock authorities so that the carcass can be handled and disposed of appropriately.
Consumers
- Purchase meat, other animal products, and dairy products from reputable suppliers that meet recognized safety standards.
- If abscesses are found in meat or internal organs, discard the entire cut. Do not remove only the abscess and consume the remaining portions.
- Cook food thoroughly to the boiling point to ensure the bacteria are destroyed.
Melioidosis can be prevented. By staying alert during the rainy season, avoiding high-risk environments, caring for animals properly, and consuming clean, thoroughly cooked food, people can significantly reduce their risk of infection. Awareness is the first and most effective line of defense.
Melioidosis: Symptoms, Treatment, and Prevention
Melioidosis is a serious infectious disease that can be life-threatening. In Thailand, the disease is most commonly found in the Northeast and South and tends to occur more frequently during the rainy season.
Symptoms
The incubation period of the infection ranges from 2 days to as long as a year before the onset of symptoms.
Symptoms range from asymptomatic to sepsis. Most patients start with a high fever, which is similar to many infectious diseases, such astuberculosis, typhoid,pyogenic bacterial infections. Some have symptoms like severe pneumonia, and others may have skin abscesses, abdominal pain, joint pain, bone aches. Therefore, laboratory tests are very important to ensure accurate and timely treatment.
The severity of symptoms depends on the extent of infection and an individual’s immune response. People with underlying conditions such as diabetes, chronic kidney disease, chronic liver disease, thalassemia, or weakened immune systems may experience more severe illness. Among patients who develop acute sepsis, the mortality rate can be as high as 40–60%.
Who is at risk?
Farmers and agricultural workers—including rice farmers, crop farmers, and rubber plantation workers—who frequently come into contact with soil, mud, and standing water.
People who consume meat from infected animals, particularly if the meat has not been thoroughly cooked.
Prevention and Treatment Recommendations
Avoid prolonged contact with muddy soil or standing water. If exposure is unavoidable, wear rubber boots or waterproof coverings to prevent direct contact with contaminated water. Any cuts or wounds should be covered with a waterproof dressing, and the body should be washed thoroughly after working outdoors or wading through water. Always drink clean or boiled water.
If you develop a sudden high fever, headache, or muscle aches, seek medical attention promptly and inform your doctor of any recent exposure to soil, mud, or floodwater. This information can help ensure timely diagnosis and appropriate treatment based on the severity of the infection.
