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Volume 17, Number 7—July 2011
Letter

Typhoon-related Leptospirosis and Melioidosis, Taiwan, 2009

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To the Editor: Global climatic changes have resulted in more natural disasters worldwide. These natural disasters can then cause outbreaks of emerging infectious diseases, including leptospirosis and melioidosis (17). In 2009, the moderate-strength Typhoon Morakot, with a maximum cumulative rainfall amount up to 3,059.5 mm, damaged Taiwan. After this natural disaster, unusual epidemics of leptospirosis and melioidosis occurred. The main objective of this study was to clarify whether these epidemics have resulted from this natural disaster.

Information about past typhoons that affected Taiwan was collected from the website of the Taiwan Meteorological Bureau (http://photino.cwb.gov.tw/tyweb/mainpage.htm; www.cwb.gov.tw) during January–August, 2009. The influential period of Morakot was in the 32nd week (August 5–August 10) in 2009. To evaluate the effects of this specific natural disaster, we divided the period into 2 intervals for analysis. The early period (before the typhoon) was from the 28th through the 32nd weeks, and the latter period (after the typhoon) was from the 33th through the 37th weeks in 2009. Information regarding 16 typhoons from 2000 through 2009 was further collected to evaluate effects of typhoon level, rainfall level, and maximum cumulative rainfall amounts on case numbers of leptospirosis and melioidosis after a typhoon.

The historical records of numbers of leptospirosis and melioidosis cases for analysis were obtained from the database collected weekly by the Centers for Disease Control, Taiwan. The information was referred to the website of the Taiwan Center for Disease Control (http://nidss.cdc.gov.tw/). To assess geographic variations, the age-adjusted incidence rates per 100,000 persons of leptospirosis and melioidosis were calculated in each city and county in Taiwan from February through September 2000–2009. SPSS version 15.0.0 software (SPSS Inc., Chicago, IL, USA), ArcGIS (ArcMap, version 9.3; ESRI Inc., Redlands, CA, USA), and SaTScan version 8.0 (www.satscan.org) were used for statistical analysis.

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Thumbnail of Comparison of epidemic curves during 2009 and 2006–2008. A) Epidemic curves of leptospirosis. B) Epidemic curves of melioidosis. 2006–2008* indicates that the curve was made by plotting the average weekly numbers.

Figure. Comparison of epidemic curves during 2009 and 2006–2008. A) Epidemic curves of leptospirosis. B) Epidemic curves of melioidosis. 2006–2008* indicates that the curve was made by plotting the average weekly numbers....

As shown by Mann-Whitney U test, frequencies of leptospirosis and melioidosis cases before the typhoon were significantly lower than those after the typhoon (all p<0.05). Furthermore, more leptospirosis and melioidosis cases were observed during the posttyphoon period in 2009 than during 2006–2008 (all p<0.05) (Figure).

Using Pearson correlation test to evaluate the effect of cumulative rainfall from Morakot, we found a positive correlation for leptospirosis (r = 0.54, p<0.05) and for melioidosis (r = 0.52, p<0.05). Effects of typhoons on numbers of leptospirosis and melioidosis cases in the late stage of a typhoon were further analyzed by using records of typhoon level and maximum 24-hour cumulative rainfall during 2000–2009. After weighting typhoon levels with scores (strong typhoon: 5 points; moderate typhoon: 3 points; mild typhoon: 1 point), we found that typhoon level with higher weight was significantly correlated with more cases of leptospirosis and melioidosis (r = 0.81 and 0.87, respectively; all p<0.05). The results further suggested that, when the 24-hour cumulative rainfall was >500 mm, significantly more meliodosis cases were observed (p<0.05). Although not statistically significant, the number of leptospirosis cases was positively correlated with 24-hour cumulative rainfall (r = 0.71; p = 0.14).

Using the Anselin local Moran statistic to evaluate geographic variations of leptospirosis and melioidosis after Morakot, we identified significantly higher incidence rates of melioidosis in Tainan, Kaohsiung, and Pingtung Counties in southern Taiwan (p<0.01). Nevertheless, no melioidosis cases were observed in Taitung, the county in the same latitude (20°N) but in eastern Taiwan. No significant geographic variation was found in the occurrence of leptospirosis. However, a high incidence of leptospirosis was observed in Pingtung, where flooding caused by Morakot was most serious (maximum cumulative rainfall >2,500 mm).

This study found that epidemics of leptospirosis and melioidosis possibly resulted from the moderate Typhoon Morakot. The findings implied that the effect of typhoon strength on the case numbers of leptospirosis and melioidosis could be less than that of rainfall level and maximum cumulative rainfall amount. Of major importance, the number of melioidosis cases was positively correlated with rainfall level >500 mm. The study further indicated that typhoon strength level and total amount of rainfall must be studied separately to determine their effects on epidemics of infectious diseases. The current typhoon classification system is only related to its intensity, which might not be always associated with total rainfall. The results of this study also implied that epidemic of melioidosis was more likely to be restricted to some geographic regions; this finding was not observed for epidemics of leptospirosis.

In conclusion, this study suggests that natural disasters, such as typhoons, that engender large amounts of rainfall could result in epidemics of leptospirosis and melioidosis. More in-depth studies need to be conducted. Efforts need to be taken in advance to prevent possible transmission of these infectious diseases after typhoons.

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Acknowledgment

We appreciate the administrative support that we received from the Centers for Disease Control, Taiwan.

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Hsun-Pi Su, Ta-Chien Chan, and Chao-Chin ChangComments to Author 
Author affiliations: Author affiliations: Centers for Disease Control–Department of Health, Taipei, Taiwan (H.-P. Su); China Medical University, Taichung, Taiwan (H.-P. Su); Kaohsiung Medical University, Kaohsiung, Taiwan (H.-P. Su); National Taiwan University, Taipei (T.C.-Chan); National Chung Hsing University, Taichung (C.-C. Chang)

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References

  1. Gaynor  K, Katz  AR, Park  SY, Nakata  M, Clark  TA, Effler  PV. Leptospirosis on Oahu: an outbreak associated with flooding of a university campus. Am J Trop Med Hyg. 2007;76:8825.PubMedGoogle Scholar
  2. Hsueh  PR, Teng  LJ, Lee  LN, Yu  CJ, Yang  PC, Ho  SW, Melioidosis: an emerging infection in Taiwan? Emerg Infect Dis. 2001;7:42833.PubMedGoogle Scholar
  3. Diaz  JH. Global climate changes, natural disasters, and travel health risks. J Travel Med. 2006;13:36172. DOIPubMedGoogle Scholar
  4. Kawaguchi  L, Sengkeopraseuth  B, Tsuyuoka  R, Koizumi  N, Akashi  H, Vongphrachanh  P, Seroprevalence of leptospirosis and risk factor analysis in flood-prone rural areas in Lao PDR. Am J Trop Med Hyg. 2008;78:95761.PubMedGoogle Scholar
  5. Ko  WC, Cheung  BM, Tang  HJ, Shih  HI, Lau  YJ, Wang  LR, Melioidosis outbreak after typhoon, southern Taiwan. Emerg Infect Dis. 2007;13:8968.PubMedGoogle Scholar
  6. Liverpool  J, Francis  S, Liverpool  CE, Dean  GT, Mendez  DD. Leptospirosis: case reports of an outbreak in Guyana. Ann Trop Med Parasitol. 2008;102:23945. DOIPubMedGoogle Scholar
  7. Su  HP, Chou  CY, Tzeng  SC, Femg  TL, Chen  YL, Chen  YS, Possible typhoon-related melioidosis epidemic, Taiwan, 2005. Emerg Infect Dis. 2007;13:17957.PubMedGoogle Scholar

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DOI: 10.3201/eid1707.101050

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Chao-Chin Chang, School of Veterinary Medicine, Graduate Institute of Microbiology and Public Health, National Chung Hsing University, Taichung 402, Taiwan

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Page created: August 15, 2011
Page updated: August 15, 2011
Page reviewed: August 15, 2011
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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