Melioidosis Outbreak after Typhoon, Southern Taiwan

From July through September 2005, shortly after a typhoon, 40 cases of Burkholderia pseudomallei infection (melioidosis) were identified in southern Taiwan. Two genotypes that had been present in 2000 were identified by pulsed-field gel electrophoresis. Such a case cluster confirms that melioidosis is endemic to Taiwan.

From July through September 2005, shortly after a typhoon, 40 cases of Burkholderia pseudomallei infection (melioidosis) were identifi ed in southern Taiwan. Two genotypes that had been present in 2000 were identifi ed by pulsed-fi eld gel electrophoresis. Such a case cluster confi rms that melioidosis is endemic to Taiwan.
M elioidosis is an infectious disease caused by Burkholderia pseudomallei and is found in northern Australia and tropical countries in Southeast Asia (1). The incidence of melioidosis cases increases during the rainy season (2). Melioidosis often affects adults who have chronic underlying diseases, especially diabetes mellitus, and is often associated with illness and death. The mortality rate varies geographically, ranging from 19% in northern Australia to 68% in northeastern Thailand (1).
The fi rst case of melioidosis in Taiwan, acquired in the Philippines, was reported in 1985 (3); since then several sporadic cases have been reported. In a recent comprehensive review, Taiwan was categorized as an area in which melioidosis may be endemic (1). However, this conclusion was deduced from a limited number of clinical cases reported in the literature. A total of 13 cases have been reported in Taiwan in patients who never traveled to melioidosis-endemic areas (4)(5)(6)(7)(8)(9)(10)(11)(12). These patients likely have indigenous cases of melioidosis, and no common source of B. pseudomallei isolates has been identifi ed. We report a cluster of 40 cases of melioidosis after a typhoon hit Taiwan, which confi rms that melioidosis is endemic in this country.

The Study
Heavy rains from Typhoon Haitang on July 16, 2005, caused mudslides and fl ooding in central and southern Taiwan. The fi rst clinical isolate of B. pseudomallei was found on July 29, 2005. Demographic and clinical data for melioidosis case-patients at 3 hospitals were collected.
Clinical information was collected on a case record form. For each patient, demographic data, including location, clinical signs, underlying illness, laboratory data, radiologic images, antimicrobial drug therapy, and clinical outcome, were obtained from medical records. Information about patients' functional levels, recent exposure to mud or water before admission, and prior travel to Southeast Asia or Australia was obtained by telephone from the patients or their families if such information was incomplete or not available on medical charts. The study was reviewed and approved by the Institutional Review Board of Chi-Mei Foundation Medical Center.
In Only the fi rst isolate from each case was studied. Two genetically distinct B. pseudomallei strains isolated in northern Taiwan (9) were used as reference strains. For pulsed-fi eld gel electrophoresis (PFGE), bacterial plugs were digested with restriction endonucleases XbaI and SpeI. Digests were subjected to gel electrophoresis using the Chef Mapper System (Bio-Rad Laboratories, Hercules, CA, USA) with a bacteriophage λ DNA ladder. Gels were stained with ethidium bromide, viewed under UV light, and analyzed by using the Molecular Analyst System (Bio-Rad Laboratories).
Of 40 patients, 30 (75%) were male. Their mean age was 64.6 years (range 38-87 years). A total of 37 (92.5%) patients never traveled abroad, and 28 (70%) denied recent contact with mud or dirty water before their illness. Because 3 patients could not walk, infection by cutaneous contact with contaminated dirt or water was less likely. Twentyseven (67.5%) patients had an underlying debilitating illness, predominantly diabetes mellitus (20 patients).
The most common initial symptoms were fever (29 patients, 72.5%) and cough (13 patients, 32.5%). Relevant prodromes lasting <72 hours before admission were noted in 25 (62.5%) patients, and 13 (32.5%) patients visited hospitals within 24 hours after onset of the illness, which suggests acute illness. The earliest onset of symptoms related XbaI restriction profi les in PFGE provide a level of resolution similar to that obtained with multilocus sequence typing for B. pseudomallei isolates (14), but the discriminative sensitivity of SpeI was greater than that of XbaI in differentiation of our B. pseudomallei isolates. Thus, genotyping information obtained from PFGE SpeI profi les is useful in epidemiologic studies. Among the 54 isolates, 2 PFGE genotypes (types A and B) were identifi ed in SpeI macrorestriction profi les (Figure 1). These genotypes were genetically distinct from the 2 reference isolates (types C and D). Genotypes A and B were found in isolates obtained as early as 2000 (Figure 2).

Conclusions
Melioidosis became a reportable disease in Taiwan    Dr Ko is an infectious disease physician at National Cheng Kung University Hospital, Tainan, Taiwan. His research interests include antimicrobial drug resistance in clinical bacterial pathogens, pathogenesis of Klebsiella pneumoniae infections, and the epidemiology and treatment of Aeromonas spp. infections.