Bacteria Behind Rare Disease Melioidosis Found in US for First Time

The CDC said Wednesday it has identified in US dirt and water samples for the first time a bacteria that causes a rare and sometimes fatal disease called melioidosis, and it is one that some scientists have been warning about for several years, not only because of its devastating impact in low-income countries, but because of its impending migration stemming from climate change.

The bacteria, Burkholderia pseudomallei, or B pseudomallei, was identified through sampling of soil and water in the Gulf Coast region of Mississippi, the CDC said, after 2 unrelated people got sick 2 years apart.

Worldwide, melioidosis, which is typically found in tropical and subtropical areas such as South and Southeast Asia, northern Australia, and parts of Central and South America and Puerto Rico, is fatal in 10% to 50% of those infected. It is underrecognized globally, and it is not officially classified as a neglected tropical disease by the World Health Organization (WHO), researchers noted in an editorial last month in The Lancet Infectious Diseases.¹ They noted that it does not cause the same level of mortality in developed countries as it does in poverty-stricken ones.

The CDC said it is unclear how long the bacteria has been in the environment and where else it might be found in this country; in a statement, the CDC said “modeling suggests that the environmental conditions found in the Gulf Coast states are conducive to the growth of B pseudomallei.”

Extensive environmental sampling is needed to know how widespread it is, the CDC said.

The CDC issued a Health Alert Network (HAN) Health Advisory to warn physicians and public health officials “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.”

The 2 individuals lived in southern Mississsippi and got sick in 2020 and 2022; they had not traveled outside of the country. Genomic sequencing data showed they 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, which include diabetes, chronic kidney disease, chronic lung disease, heavy alcohol use, and immunosuppressant therapy.

Blood cultures were positive for B pseudomallei, and both patients recovered after antibiotic therapy.

With the patients' permission, state health officials and the CDC conducted testing last month on soil, water, and plant matter from around their homes and nearby areas they visited, as well as household products. Three of the samples taken from soil and puddle water tested positive for B pseudomallei, indicating bacteria from the environment was the likely source of infection for both individuals and has been present in the area since at least 2020.

Melioidosis has a wide range of nonspecific symptoms like fever, joint pain, and headaches and can cause conditions that include tuberculosis, pneumonia, abscess formation, or blood infections. Symptoms may appear within weeks of infection, or years later.

Historically, the number of cases in the United States total about 12, due to overseas travel. The CDC said it believes the risk of melioidosis for most of the country "continues to be very low."

Worldwide, prevalence has been difficult to determine because it primarily affects the rural poor. One study published in 2019 estimated that the burden for the disease expressed in disability-adjusted life-years was 4.6 million, or 84 per 100,000 people.² An earlier study by some of those same authors estimated the worldwide death toll at about 89,000 individuals, although it could be much higher.

A 2017 paper described how the combination of heavy rainfall and cloud cover on B pseudomallei, increasing temperatures, changing precipitation patterns, and extreme weather events around the world are creating an atmosphere that is hospitable for increased cases of melioidosis.³

B pseudomallei is also classified as a bioterror threat by the CDC, due to "the ease with which strains may be obtained from the environment, the ability to engineer strains that are resistant to multiple antibiotics, and the lack of a vaccine," according to the Center for Health Security at the Bloomberg School for Public Health at Johns Hopkins.

Once B pseudomallei is in the soil, it can't be eradicated, the CDC said. It advised residents and visitors to the Gulf Coast, particularly ones with diabetes and other chronic health conditions, to avoid contact with soil or muddy water and protect open wounds.

References

1. Salvelkoel J, Dance DAB, Currie BJ, Limmathurotsakul D, Wiersinga J. A call to action: time to recognise melioidosis as a neglected tropical disease. Lancet Infect Dis. 2022;22(6):e176-e182. doi:10.1016/S1473-3099(21)00394-7

2. Birnie E, Virk HS, Savelkoek j, et al. Global burden of melioidosis in 2015: a systematic review and data synthesis. Lancet Infect Dis. 2019;19(8):892-902. doi:10.1016/S1473-3099(19)30157-4

3. Merritt AJ, Inglis TJJ. The role of climate in the epidemiology of melioidosis. Curr Trop Med Rep. 2017;4(4):185-191. doi:10.1007/s40475-017-0124-4