What Is Melioidosis? Three People in U.S. Infected With Rare Disease, CDC Says

Earlier this week, the Centers for Disease Control and Prevention (CDC) announced that it was investigating three cases of a rare and serious bacterial infection known as melioidosis, alongside the state health departments of Texas, Kansas and Minnesota.

The cases are unusual given that the disease is endemic to tropical and subtropical climates—particularly Southeast Asia and northern Australia where it is widespread. Most cases of the disease in the U.S.—around a dozen of which are identified every year—tend to occur in people who have recently been in these areas. But none of the three individuals had reported traveling outside of the continental United States.

The CDC said Wednesday that the three cases—one male and two females—may share a common source of exposure, such as an imported product or animal, but it is not yet clear what this is. Officials identified the first case in March, and the individual ended up dying. Two more cases were identified in May—one of whom is still hospitalized, while the other has been discharged to a transitional care unit.

What is melioidosis?

Melioidosis, also known as Whitmore's disease, is an infectious disease caused by the bacteria, Burkholderia pseudomallei, that can affect humans and animals.

The bacteria is found in contaminated water and soil. Humans and animals that come into direct contact with a contaminated source can be infected. The main routes of infection are inhalation of contaminated dust or water droplets, ingestion of contaminated water or soil-contaminated food, and contact with contaminated soil, particularly when the individual has skin abrasions.

The disease is not thought to be transmitted person-to-person via air respiratory droplets. In fact, human-to-human transmission is very rare, with only a handful of documented cases. Animals that are susceptible to the disease beside humans are sheep, goats, pigs, horses, cats, dogs and cattle.

According to the CDC, the symptoms of melioidosis vary depending on the type of infection: localized, pulmonary, bloodstream or disseminated.

For a localized infection, symptoms can include localized pain or swelling, fever, ulcerations and abscesses. Pulmonary infections—one that affects the lungs—can lead to coughing, chest pain, high fever, headache and anorexia.

If the bacteria infects the bloodstream, patients may experience fever, headache, respiratory distress, abdominal discomfort, joint pain and disorientation. Symptoms of a disseminated infection, meanwhile, include fever, weight loss, stomach or chest pain, muscle or joint pain, headache and seizures.

Because melioidosis produces such a wide range of symptoms, it is often mistaken for other diseases, such as tuberculosis or more common forms of pneumonia.

The time between exposure to the bacteria and onset of symptoms can vary significantly, from one day to several years, although symptoms generally appear between two to four weeks later.

The disease can be treated with antimicrobial therapies. People with certain underlying medical conditions—such as diabetes, liver disease or cancer—may be at higher risk. The fatality rate for the disease varies widely depending on the clinical presentation of symptoms, ranging between 10 percent and 50 percent.

A bacterial colony
Stock image showing a bacterial colony. Three cases of a rare disease caused by the bacteria Burkholderia pseudomallei have been identified in the U.S. iStock