Ongoing Multistate Investigation of Melioidosis Cases

Aug 26, 2021 | Meghan Macaskill and Marinanicole Miller | Outbreak News


Melioidosis, also known as Whitmore’s disease, is a neglected tropical disease caused by the gram-negative bacterium Burkholderia pseudomallei [1]. It is primarily seen in Southeast Asia and northern Australia and is spread through direct contact with contaminated soil and surface water [1]. Melioidosis infections are associated with high case-fatality rates and can present with a wide range of general symptoms that could be mistaken for other diseases [1]. Infections may occur in the lungs, bloodstream, localized areas, or may be disseminated [1]. Some potential signs and symptoms include fever, headache, cough, weight loss, disorientation, anorexia, respiratory distress, chest pain, abdominal pain, joint pain, and seizures [1]. The time between exposure to the bacteria and onset of symptoms is usually between 2-4 weeks; however, the incubation period is not well defined [1]. Those most at risk for severe melioidosis are people with medical conditions, including diabetes, liver failure, renal disease, thalassemia, cancer, or chronic lung conditions [1].  

Multistate Outbreak of Unknown Origin

While Burkholderia pseudomallei can be found in other parts of the world, the only places it naturally occurs in the United States is Puerto Rico and the U.S. Virgin Islands. Due to this, most melioidosis infections occurring in the United States are a result of international travel. However, recently there have been four cases of melioidosis identified in citizens from non-adjacent states with no travel history. The first case was identified in March 2021 in a Kansas resident who ultimately succumbed to the disease [2]. In May 2021, two additional cases were identified in Texas and Minnesota, both cases were hospitalized for an extended period of time and then discharged to transitional care facilities [2]. Finally, the most recent case was a Georgia resident who was identified post-mortem in late July of 2021 [3].

Based on genomic analysis, it is believed all four cases are related and shared a common exposure. The CDC has been working alongside the Kansas Department of Health and Environment, the Texas Department of State Health Services, the Minnesota Department of Health, and the Georgia Department of Public Health to investigate these cases [3]. Of the four identified cases, children, adults, males, and females were each affected [2]. After testing over 100 samples from soil, water, and products around the victims’ homes, no source has been identified [4]. The CDC now believes that the patients likely became infected with B. pseudomallei from an imported product [4]. Although the bacteria is usually found in soil or water, it has also been previously identified in moist products in regions where it is most common [4]. If an imported product is causing this outbreak, it could be a food, drink, personal care item, cleaning product, or medicine leaving the list of potential sources endless [4]. Due to the geographical spread of the patients, the wide timeframe they were identified, and the long timeframe between exposure and symptom onset, it is difficult to pinpoint a source [4].

The CDC sent an alert to all US clinicians warning them to consider melioidosis if they see a patient who is not responding to antibiotics regardless of their travel history [4]. The CDC also is urging doctors to consider melioidosis for sick children and for patients with no known risk factors for melioidosis [4].

Bacterial Genotyping in Texas

In 2018, there was a case of melioidosis in a 63-year old Texas resident with no recent travel history outside the US [5]. 56 samples were tested in and around the patient’s home and all came back negative [5]. Following whole-genome sequencing, it was discovered that the isolate matched closely to a 2004 case of melioidosis in a Texas resident residing in the same county [5]. Other isolates from southwestern United States, including a case from 1999 in Arizona, grouped closely to the 2004 and 2018 isolates [5]. This suggests that there may be unknown local exposures occurring in Texas or other areas of the United States. However, environmental sampling for B. pseudomallei in Texas has consistently come back negative. Therefore, endemicity is yet to be confirmed.








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