COLORADO SPRINGS — The Centers for Disease Control and Prevention (CDC) identified the presence of a bacteria in soil and water for the first time in the United States that can lead to an infection that causes severe pneumonia-like symptoms.

B. pseudomallei was identified through environmental sampling of soil and water in the Gulf Coast region of southern Mississippi during an investigation of two human melioidosis cases.

This bacterium causes a rare and serious disease called melioidosis. Melioidosis may present as a localized infection, pneumonia, bacteremia, or disseminated infection and can infect any organ, including the brain.

It is unclear how long the bacterium has been in the environment prior to 2020 or how widespread the bacterium is in the continental United States. Modeling suggests that the environmental conditions found in the Gulf Coast states are conducive to the growth of B. pseudomallei. However, more extensive environmental sampling is needed to answer these questions, says CDC.

The two melioidosis patients that led to this discovery were unrelated to each other but lived in close geographical proximity in the Gulf Coast region of southern Mississippi. Both had no recent travel outside of the US.

They were diagnosed with melioidosis two years apart in July 2020 and May 2022. Genomic sequencing data revealed the two patients were infected by the same novel strain from the Western Hemisphere. Both patients were hospitalized with sepsis due to pneumonia and had known risk factors for melioidosis. Blood cultures were positive for B. pseudomallei, and both patients recovered following appropriate antibiotic therapy.

In June 2022, the Mississippi State Department of Health and CDC collected environmental samples (soil, water, plant matter) from the patients’ properties and nearby areas they frequented and household products. Three of the samples taken from soil and water from the property of the 2020 patient tested positive at CDC for B. pseudomallei by polymerase chain reaction (PCR) and culture. 

B. pseudomallei isolates from both patients and environmental samples were all genetically similar and were distinct from previously known isolates. This indicated that bacteria from the environment was the likely source of infection for both patients and has been present in the area since at least 2020.

Burkholderia pseudomalle is a gram-negative bacterium and Tier 1 Select Agent that typically lives in soil and water in regions with tropical and subtropical climates around the world, such as South and Southeast Asia, northern Australia, parts of Central and South America, the U.S. Virgin Islands, and Puerto Rico.

It can infect both animals and humans through direct contact with non-intact skin (such as cuts or wounds) or mucous membranes, inhalation, or ingestion. B. pseudomallei is not considered to be transmissible via respiratory droplets in non-laboratory settings.

The risk of spread from person to person is considered extremely low as there are few documented cases of person-to-person transmission; contact between damaged (non-intact) skin and contaminated soil or water is the most frequent route for natural infection.

For the majority of cases, symptoms occur one to 21 days from exposure, with an average of seven days; with a high inoculum, symptoms can develop in a few hours. In about 5% of cases, symptoms can develop from latent-activated infections well past this 21-day window, months to years later.

Among the average of 12 melioidosis cases reported to CDC each year, most have occurred in people with recent travel to a country where B. pseudomallei is known to be endemic.

In the US, a few cases of melioidosis may have been due to contact with contaminated commercial products imported from disease-endemic countries. This occurred in 2021 when a cluster of four cases in four states were linked to an imported contaminated aromatherapy spray.

Symptoms of Melioidosis:

Melioidosis symptoms are nonspecific and vary depending on the type and site of infection. Symptoms may include fever, localized pain or swelling, ulceration, abscess, cough, chest pain, respiratory distress, weight loss, abdominal discomfort, muscle or joint pain, disorientation, headache, and seizures.

Patients generally present with acute illness, but about 9% present with chronic infection, with symptoms lasting over two months. Chronic melioidosis cases often mimic tuberculosis clinically.

In regions where melioidosis is highly endemic, such as Thailand and Northern Australia, most healthy people who come into contact with B. pseudomallei never develop melioidosis. People with certain conditions are at higher risk of disease when they are exposed to the bacteria. 

The most common underlying conditions that make a person more likely to become sick with or die from melioidosis include diabetes, excessive alcohol use, chronic lung disease, chronic kidney disease, and immunosuppressive conditions. Worldwide, 10-50% of melioidosis cases result in death [7].

Prompt diagnosis and treatment are critical. Melioidosis is confirmed by culture. Testing must be conducted by trained personnel because some automated identification methods in clinical laboratories may misidentify B. pseudomallei as a different bacterium (see recommendations for laboratorians).

Treatment of melioidosis requires long-term antibiotic therapy (acute phase followed by eradication phase). Healthcare personnel are generally not at risk if they follow standard precautions. However, laboratory personnel are at increased risk because some lab procedures may aerosolize particles and release B. pseudomallei into the air.

Once well-established in the soil, B. pseudomallei cannot feasibly be removed from the soil. Public health efforts should focus primarily on improving identification of cases so that appropriate treatment can be administered. Melioidosis is now a Nationally Notifiable Disease following a favorable vote at the 2022 CSTE conference which should enhance domestic surveillance and public health response.

This Health Alert Network (HAN) Health Advisory serves to alert clinicians and public health officials throughout the country to consider melioidosis in patients whose clinical presentation is compatible with signs and symptoms of the disease, regardless of travel history to international disease-endemic regions, as melioidosis is now considered to be locally endemic in areas of the Gulf Coast region of Mississippi.