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Author affiliation: Author affiliations: Georgia Department of Public Health, Atlanta, Georgia, USA (S. Brennan, C. Drenzek, J. Gabel); Centers for Disease Control and Prevention, Atlanta, Georgia (J.M. Thompson, C.A. Gulvik, T.K. Paisie, M.G. Elrod, J.E. Gee, C.A. Schrodt, K.M. DeBord, B.T. Richardson, Jr., W.A. Bower, A.R. Hoffmaster, Z.P. Weiner, C.M. Cossaboom).
Melioidosis is a potentially severe disease caused by the gram-negative environmental bacterium Burkholderia pseudomallei (1), which is predominantly found in tropical and subtropical regions. The median incubation is 4 days (total range 1–21 days) after exposure. Clinical manifestations vary, and infection can cause local or disseminated disease, including fulminant sepsis. Mortality ranges from <10% with early recognition and access to intensive care to >40% without treatment (1,2). Melioidosis does not develop from B. pseudomallei exposure in most persons, but comorbidities such as diabetes, which is prevalent in the southeastern United States (3), increase the risk (2).
Most melioidosis cases in the United States are associated with travel to endemic areas, but some were domestically acquired after exposure to imported household products (4,5). In 2022, three human cases were genetically linked to environmental B. pseudomallei isolated from the US Gulf Coast (6). Predictive modeling studies suggest environmental conditions in the southeastern United States are suitable for B. pseudomallei (7). In endemic regions, infections increase during the rainy season and after severe weather events such as hurricanes (1,2,8,9). The Atlantic hurricane season spans from June 1–November 30 annually (10).
On September 26, 2024, category 4 Hurricane Helene made landfall in Georgia, USA (Table), resulting in heavy rainfall, flooding, and windspeeds reaching 100 mph. On October 9, blood cultures from 2 patients in Georgia were presumptive positive for B. pseudomallei. The Georgia Department of Public Health discovered the patients shared a common worksite with exposure to mud, dust, wind, and 10 inches of rain.
Patient 1, a man in his 50s with no comorbidities, no reported international travel, and no US military service, reported working in muddy conditions on September 26, 2024. He performed routine vehicle inspections involving checking air pressure of vehicle tires, high-pressure hosing, and physical contact with mud. He became ill on September 28 and was hospitalized October 2 with fever, chills, weakness, and shortness of breath. Chest, abdominal, and pelvic imaging were unremarkable. Healthcare providers diagnosed severe sepsis. After the presumptive positive blood culture, treatment with 30 days of intravenous meropenem and oral doxycycline began on October 9, and then 3 months of oral doxycycline (11) was initiated. The patient was discharged on October 16.
Patient 2, a man in his 60s with no comorbidities, travel to the Bahamas in 2022, and no US military service, reported operating heavy equipment at the worksite during September 26–29, 2024, and frequent contact with soil. We could not confirm if he performed high-pressure hosing. He became ill on September 29 and was hospitalized October 1 for fever, chills, weakness, confusion, and body aches. Chest imaging revealed pneumonia. Results of abdominal and pelvic imaging were unremarkable. Healthcare providers diagnosed severe sepsis without septic shock. After presumptive positive blood cultures, treatment with 30 days of intravenous ceftazidime and oral doxycycline began on October 9, and then 3 months of oral doxycycline (11) was initiated. The patient was discharged October 10.
Patient 2 was readmitted on November 9 for fatigue, malaise, weakness, and shortness of breath. Abdominal and pelvic imaging suggested prostatitis. The patient received 6 weeks of intravenous meropenem and oral doxycycline beginning November 15 and then 3 months of oral doxycycline. Blood and urine cultures were positive for B. pseudomallei. Repeat blood cultures had no growth by November 12. The patient was discharged on November 15 and was lost to follow-up.
Figure 1
Figure 1. Global maximum-likelihood phylogenetic tree of core-genome single-nucleotide polymorphisms comparing new isolate genomes from 4 related melioidosis cases with unknown exposure source, Georgia, USA, 1983–2024 (red dashed red rectangle), with all …
We confirmed the patient isolates as B. pseudomallei by using the Centers for Disease Control and Prevention’s (CDC) Laboratory Response Network algorithm. We extracted isolate DNA for whole-genome sequencing (WGS) as previously described (6). Multilocus sequence typing (ST) indicated all isolates were ST41, which is associated with strains of Eastern Hemisphere origin. Phylogenetic analysis indicated the new patient-derived genomes grouped with strains from East and Southeast Asia (Figure 1) (6).
Figure 2
Figure 2. Subpanel maximum-likelihood phylogeny of refined mutation-only core single-nucleotide polymorphism sites of isolate genomes from 4 related melioidosis cases with unknown exposure source, Georgia, USA, 1983–2024, which includes the clinical isolates…
We conducted WGS on 7 B. pseudomallei isolates from CDC’s multidecade surveillance archive on the basis of ST or geographic proximity to the 2024 cases for higher resolution analysis (6). Five isolates were ST41 and clustered with the 2024 patient-derived genomes (12,13). Two isolates were from 1 person who traveled to Vietnam, 2 were from 2 retired US military members, and data were limited for 1 (Figure 2). The bacterial genomes from the 2024 patients were highly related to each other and to the 2 from the retired US military members (<20 single-nucleotide polymorphisms apart across all genomes). One publicly available ST41 genome related to this cluster was from a patient who traveled to Vietnam.
We requested medical and military service records from the National Archives and Records Administration for the 2 retired service members, who died from melioidosis in 1989 and 1983. At the time of their deaths, both lived in the same county in Georgia as the 2024 patients. Records were incomplete for patient 3, who died in October 1989. He was a US Army and Air Force Veteran who served in World War II and had no records of service in Vietnam. He was hospitalized at a Veterans Affairs facility in Georgia before his death. Patient 4, who died in October 1983, was a US Navy and Army veteran who served in World War II, the Korean War, and the Vietnam War. For 20 years, he worked on a military base located <1 mile from the shared worksite of the 2024 patients. Records indicate patient 3 retired 36 years before his death and patient 4 12 years before his death. Weather records indicate no hurricanes affected the area in 1983. In September 1989, Hurricane Hugo made landfall in the United States as a Category 4 storm and affected this area of Georgia with 3–5 inches of rain.
This investigation identified 4 presumptive autochthonous human melioidosis cases in Georgia, USA. Without leveraging historical surveillance isolates archived at CDC, we would have concluded the 2024 cases represented a potential new local or imported exposure. However, the relatedness of patient-derived isolates and the close geographic proximity of all 4 patients in Georgia are strongly suggestive of a shared, locally acquired environmental exposure, dating back to the 1980s. Only patient 4 was known to have traveled to Southeast Asia in his lifetime. Although activation of B. pseudomallei from latency 2 decades after exposure during the Vietnam War is plausible, it is rare (14). Further, retrospective review of available medical records from patients 3 and 4 revealed no earlier illnesses or hospitalizations consistent with melioidosis, and reactivation would not explain the epidemiologic and WGS links to the other cases. Persistence of a single ST of B. pseudomallei in the environment over several decades has been reported (15). Introduction and persistence of B. pseudomallei in the environment from repatriation of personnel or equipment associated with the Vietnam War is possible, but other sources of environmental introduction or local exposure cannot be ruled out. Isolation of B. pseudomallei from the environment is needed to determine local endemicity and characterize the public health risk.
Trimethoprim/sulfamethoxazole (TMP/SMX) is the recommend first-line antimicrobial drug for B. pseudomallei infection; doxycycline is indicated with TMP/SMX intolerance. Relapses are more common with doxycycline compared with TMP/SMX (11).
All 4 patients from Georgia became ill or died in September and October. High wind speeds, rain, or flooding associated with hurricanes might have contributed to infections in 3 of the patients. Because hurricanes regularly affect the US (10), increased knowledge of melioidosis among healthcare providers is needed, particularly if patients have contact with floodwater, mud, or debris. Persons should wear waterproof clothing or boots, cover wounds if they cannot avoid floodwater, and follow local safety guidance during hurricanes.
Ms. Brennan is the zoonotic disease epidemiologist at the Georgia Department of Public Health. She oversees surveillance of notifiable zoonotic diseases, including bioterrorism agents and rabies.
