Credit CDC PHIL
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Melioidosis, aka Whitmore’s disease, is caused by a Burkholderia pseudomallei infection - a bacteria which is normally found in tropical regions (primarily Southeast Asia and northern Australia) - but has not (at least, until now) been found in the continental United States.Cases here have been exceeding rare, usually occurring among people with recent travel to endemic regions of the world.
The causative agent - Burkholderia pseudomallei - is a gram negative saprophytic (feeds on dead or decaying organic matter) bacterium that is often found in soil and water in endemic regions. This is a particularly nasty pathogen - enough so that is is considered to have at least some bioterrorism applications.
From the CDC website.
Melioidosis is a disease caused by germs that occur naturally in certain parts of the world, such as Southeast Asia and northern Australia. The only places these germs, called Burkholderia pseudomallei, occur naturally in the United States is Puerto Rico and U.S. Virgin Islands. One reason public health authorities study the disease is because it is possible that the germs that cause melioidosis might be used in a biological attack. A biological attack is the intentional release of germs that can sicken or kill people, livestock, or crops.
About a dozen (usually imported) human infections are reported in the United States each year. As we saw two years ago in an EID Journal dispatch (see Melioidosis in a Resident of Texas with No Recent Travel History, United States), sometimes the source of infection is never determined.
Researchers from the CDC and Texas identified at least 4 cases (over 20 years) in the Southwestern United States with unknown exposures, prompting them to write:
Isolates TX2004 and TX2018b were collected ≈15 years apart from patients living in the same Texas county at time of illness onset and group together, a finding that suggests B. pseudomallei might be present in the environment in this area. Furthermore, these 2 isolates might represent a new clade endemic to the continental United States. Further investigation is warranted because this region is predicted to have suitable habitats for B. pseudomallei (14).
CDC HAN Update: 4th Case of Non-Travel Related Melioidosis Reported - Georgia
CDC HAN: Multi-state Investigation of Non-travel Associated Melioidosis in Three Patients: Kansas, Texas, and Minnesota—2021
After months of investigation, in October of 2021 the CDC announced a promising break in the investigation (see CDC Update On Multi-State Outbreak Of Melioidosis), when B. pseudomallei was detected in a bottle of imported aromatherapy spray found in the home of the 4th victim (from Georgia).
A recall was announced, as investigators continued to try to link the three other cases to the imported aromatherapy product.
Meanwhile, last December the CDC's EID Journal published details on yet another unusual domestic case from 2019 (see Human Melioidosis Caused by Novel Transmission of Burkholderia pseudomallei from Freshwater Home Aquarium, United States) which appears to be linked to imported tropical fish.
Yesterday, the plot thickened once more when the CDC announced - as hypothesized in the Texas study above - the first detection of environmental B. pseudomallei in the continental United States, and published the following HAN Advisory after two residents of Mississippi were found to be infected with the same novel strain (in 2020, and 2022).
Melioidosis Locally Endemic in Areas of the Mississippi Gulf Coast after Burkholderia pseudomallei Isolated in Soil and Water and Linked to Two Cases – Mississippi, 2020 and 2022
Distributed via the CDC Health Alert Network
July 27, 2022, 3:30 PM ET
CDCHAN-00470
Summary
The Centers for Disease Control and Prevention (CDC) identified the bacterium Burkholderia pseudomallei (B. pseudomallei) for the first time in the environment in the continental United States. This bacterium causes a rare and serious disease called melioidosis. 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.
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 [1]. Extensive environmental sampling is needed to answer these questions.
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.
Background
The two melioidosis patients that led to this discovery were unrelated to each other but lived in close geographical proximity to each other in the Gulf Coast region of southern Mississippi. Both had no recent travel outside of the United States. 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.
With permission from both patients, 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 the environmental samples were all genetically similar and were distinct from previous known isolates, indicating bacteria from the environment was the likely source of infection for both patients and has been present in the area since at least 2020.
The CDC also published the following announcement, with advice for people living and working in the affected region:
Bacteria that Causes Rare Disease Melioidosis Discovered in U.S. Environmental Samples
Press Release
For Immediate Release: Wednesday, July 27, 2022
Contact: Media Relations
(404) 639-3286
The Centers for Disease Control and Prevention (CDC) has identified for the first time in domestic environmental samples the bacteria that causes a rare and serious disease called melioidosis. The bacteria, Burkholderia pseudomallei or B. pseudomallei, was identified through sampling of soil and water in the Gulf Coast region of Mississippi.
It is unclear how long the bacteria has been in the environment and where else it might be found in the U.S.; however, modeling suggests that the environmental conditions found in the Gulf Coast states are conducive to the growth of B. pseudomallei. CDC is alerting clinicians throughout the country of this discovery through a national health advisory, reminding them to be aware of the signs and symptoms of melioidosis and to consider melioidosis in patients that present with symptoms of the disease.
Two unrelated individuals living in close geographic proximity in the Gulf Coast region of the southern United States became sick with melioidosis two years apart—in 2020 and 2022— prompting state health officials and CDC to take samples and test household products, soil, and water in and around both patients’ homes, with permission. Three of the samples taken from soil and puddle water in 2022 tested positive at CDC 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 is caused by direct contact with B. pseudomallei, which is found in contaminated soil and water. Among the average of 12 melioidosis cases diagnosed in the United States each year, most have occurred in people with recent travel to a country where this bacteria is endemic. Cases of melioidosis have also been linked to contaminated commercial products imported from disease-endemic countries. This recently occurred in 2021 when a cluster of four cases in four states were linked to an imported contaminated aromatherapy spray
Melioidosis has a wide range of nonspecific symptoms like fever, joint pain, and headaches and can cause conditions that include pneumonia, abscess formation, or blood infections. Worldwide, melioidosis is fatal in 10 – 50% of those infected. B. pseudomallei has historically been found in tropical and sub-tropical areas such as South and Southeast Asia, northern Australia, and parts of Central and South America and Puerto Rico. Given the very small number of cases of melioidosis identified historically in the United States, CDC believes the risk of melioidosis for the general population continues to be very low.
Individuals living in the Gulf Coast of Mississippi and who have health conditions that may put them at higher risk—such as diabetes, chronic kidney disease, chronic lung disease, or excessive alcohol use— should take precautions to protect themselves:
- Avoid contact with soil or muddy water, particularly after heavy rains, and protect open wounds with waterproof dressings.
- Wear waterproof boots when gardening, doing yard work, or doing agricultural work, which can prevent infection through the feet and lower legs—particularly after flooding or storms.
- Wear gloves to protect the hands when working directly with soil.
CDC encourages healthcare providers in the Gulf Coast region of the southern United States as well as clinicians throughout the country to learn about melioidosis and to be aware of the potential for more cases as CDC and partners continue to investigate the geographic spread of B. pseudomallei. As a nationally notifiable disease, melioidosis should always be reported to the state health department.
For more information, visit CDC’s melioidosis website.
It is worth noting that we are entering the heart of hurricane season (Aug-Sep-Oct), which can bring flooding rains to the gulf coast, and which can force people into working in muddy, often dangerous conditions (see Flood Dangers Run Deep).
Aside from potential injury from a wide assortment of physical objects in the water (snakes, alligators, broken glass, nails, etc.) we've also seen cases of Vibrio vulnificus infection (see Vulnerable To Vibrio) spike following coastal flooding events.
In 2019, prior to Tropical storm Barry, NOLA.Com ran an article called Floodwater in New Orleans like 'toxic' stew, experts warn, after social media posts showed people swimming in the previous day's flood waters.
There are plenty of other goods reasons to stay out of flood waters, but the local detection of B. pseudomallei - rare though it may be - adds one more.