MAJOR ARTICLE
Contact Investigation of Melioidosis Cases Reveals Regional Endemicity in Puerto Rico Thomas J. Doker,1,2 Tyler M. Sharp,3 Brenda Rivera-Garcia,4 Janice Perez-Padilla,3 Tina J. Benoit,2 Esther M. Ellis,1,3 Mindy G. Elrod,2 Jay E. Gee,2 Wun-Ju Shieh,5 Cari A. Beesley,2 Kyle R. Ryff,4 Rita M. Traxler,2 Renee L. Galloway,2 Dana L. Haberling,6 Lance A. Waller,7 Sean V. Shadomy,2 William A. Bower,2 Alex R. Hoffmaster,2 Henry T. Walke,2 and David D. Blaney2 1
Epidemic Intelligence Service, and 2Bacterial Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, Georgia; 3Dengue Branch, Centers for Disease Control and Prevention, and 4Puerto Rico Department of Health, San Juan; 5Infectious Diseases Pathology Branch, 6Prion and Public Health Office, Centers for Disease Control and Prevention, and 7Department of Biostatistics and Bioinformatics, Rollins School of Public Health, Emory University, Atlanta, Georgia
(See the Editorial Commentary by Dance on pages 251–3.)
Background. Melioidosis results from infection with Burkholderia pseudomallei and is associated with casefatality rates up to 40%. Early diagnosis and treatment with appropriate antimicrobials can improve survival rates. Fatal and nonfatal melioidosis cases were identified in Puerto Rico in 2010 and 2012, respectively, which prompted contact investigations to identify risk factors for infection and evaluate endemicity. Methods. Questionnaires were administered and serum specimens were collected from coworkers, neighborhood contacts within 250 m of both patients’ residences, and injection drug user (IDU) contacts of the 2012 patient. Serum specimens were tested for evidence of prior exposure to B. pseudomallei by indirect hemagglutination assay. Neighborhood seropositivity results guided soil sampling to isolate B. pseudomallei. Results. Serum specimens were collected from contacts of the 2010 (n = 51) and 2012 (n = 60) patients, respectively. No coworkers had detectable anti–B. pseudomallei antibody, whereas seropositive results among neighborhood contacts was 5% (n = 2) for the 2010 patient and 23% (n = 12) for the 2012 patient, as well as 2 of 3 IDU contacts for the 2012 case. Factors significantly associated with seropositivity were having skin wounds, sores, or ulcers (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.2–17.8) and IDU (OR, 18.0; 95% CI, 1.6–194.0). Burkholderia pseudomallei was isolated from soil collected in the neighborhood of the 2012 patient. Conclusions. Taken together, isolation of B. pseudomallei from a soil sample and high seropositivity among patient contacts suggest at least regional endemicity of melioidosis in Puerto Rico. Increased awareness of melioidosis is needed to enable early case identification and early initiation of appropriate antimicrobial therapy. Keywords.
melioidosis; Burkholderia pseudomallei; Puerto Rico; emerging infectious disease.
Melioidosis is an acute febrile illness resulting from infection with the gram-negative bacillus Burkholderia pseudomallei, and can have case-fatality rates as high as 40% [1]. Clinical presentations range from skin or soft tissue abscesses to fulminant septicemia, although
Received 18 June 2014; accepted 7 September 2014; electronically published 30 September 2014. Correspondence: David D. Blaney, MD, MPH, FACPM, Centers for Disease Control and Prevention, 1600 Clifton Rd, MS A-30, Atlanta, GA 30333 (
[email protected]). Clinical Infectious Diseases® 2015;60(2):243–50 Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US. DOI: 10.1093/cid/ciu764
the most common presentation is acute pneumonia with or without septicemia [1, 2]. Up to 80% of patients with melioidosis have 1 or more risk factors for illness, including diabetes, excessive alcohol use, and chronic lung disease [3]. Melioidosis should be considered an opportunistic pathogen in persons with these conditions. Improved survival rates are attributed to access to care, early diagnosis, and treatment with appropriate antimicrobials [3]. Although B. pseudomallei grows readily in commercially available blood culture media, it is not unusual for laboratory staff to misidentify the bacteria [4, 5] or dismiss positive results as a culture contaminant [6].
Melioidosis Investigations: Puerto Rico
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Individuals in regular contact with soil or water harboring B. pseudomallei are at highest risk for acquiring melioidosis [1]. The primary routes of infection are percutaneous inoculation, ingestion, and inhalation; person-to-person transmission is rare [2, 7]. Melioidosis is considered to be highly endemic in northeast Thailand, Malaysia, Singapore, and northern Australia; endemic throughout much of south-central and maritime Southeast Asia; and sporadic in Africa and Latin America, including the Caribbean basin [8]. Three locally acquired cases of melioidosis were reported from the United States territory of Puerto Rico in 1982 [9], 1998 [10], and 2003 [11] (Table 1). In 2009, a fourth case occurred in a resident of Puerto Rico who sought medical care in Florida due to fever, cough, and anorexia (Centers for Disease Control and Prevention [CDC] and Florida Department of Health, unpublished data, 2009). All 4 patients were residents of the eastern side of the island. In the 3 prior Puerto Rican cases for which multilocus sequence typing (MLST) results were available, either sequence type 297 (ST297) or a single- or double-locus variant of ST297 was identified [12]. All 3 patient B. pseudomallei isolates were determined to be type G using internal transcriber spacer (ITS) typing. B. pseudomallei isolates from the Western Hemisphere are consistently type G [12]. Following identification of melioidosis cases in 2010 and 2012, an investigation was conducted to describe the patients’ illnesses, determine location of exposure (ie, home vs work), identify risk factors for infection, and conduct environmental sampling to isolate B. pseudomallei from soil. METHODS In November 2012, the Puerto Rico Department of Health and the CDC investigated the melioidosis cases from 2010 and 2012. To assess possible risk factors for exposure to B. pseudomallei and development of melioidosis, a standardized questionnaire was developed that collected information on demographics, behavioral practices, and medical histories. The exposure period for investigation participants was the month prior to and the 2 months after the onset of illness of the 2010 and 2012 patients for each respective exposure location. Serum specimens were collected from consenting household contacts and coworkers of each case for detection of anti–B. pseudomallei antibody by indirect hemagglutination assay (IHA); seropositivity was defined by an IHA titer ≥1:40 [13]. In December 2012, the investigation was expanded to include a 250 meter sampling radius around each patient’s household. Although all households within this radius were visited during investigation of the 2010 case, only 1 in 3 houses within this radius were visited during investigation of the 2012 case due to high household density. Clusters of 3 households were designated, and the first household with an available respondent in each cluster was offered participation.
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Households that declined participation were not replaced. Verbal informed consent was obtained from individuals ≥18 years of age or from the parent or guardian of individuals
