2015年10月10日 星期六

研究登革熱的數學方法

Nature 427 (6972)
發表日期:2004年1月22日
登革熱是作為本期封面文章的一篇結构論文所研究的對象,每年受其影響的人口多達1億。登革熱最嚴重的傳染形式為登革出血熱,會對東南亞國家的醫療衛生體系造成沉重負擔。一組流行病學家、數學家和物理學家,用一种最初由NASA開發用來分析物理材料中的波的數學方法,對登革熱病例的“流行波”進行了研究。分析結果表明,泰國的登革熱疫情在傳播速度上表現出一個可預測的三年振蕩,疫情發源于曼谷,然后向全國各地傳播,傳播速度可達每月148公里,相當于疾病的一個“行波”。因此,對大城市進行有效監測,有可能對疫情進行早期預警,使人們有時間采取措施消滅傳播該疾病的蚊子,有時間正确分配有限的公共衛生資源。
Travelling waves in the occurrence of dengue haemorrhagic fever in Thailand
Derek A.T. Cummings1,2, Rafael A. Irizarry3, Norden E. Huang4, Timothy P. Endy5, Ananda Nisalak6, Kumnuan Ungchusak7 & Donald S. Burke2
  1. Department of Geography and Environmental Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA
  2. Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
  3. Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21205, USA
  4. Laboratory for Hydrospheric Processes/Oceans and Ice Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
  5. Virology Division, United States Army Medical Research Institute in Infectious Disease, Fort Detrick, Maryland 21702, USA
  6. Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok 10400, Thailand
  7. Bureau of Epidemiology, Ministry of Public Health, Nonthaburi 11000, Thailand
Correspondence to: Donald S. Burke2 Email: dburke@jhsph.edu

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Dengue fever is a mosquito-borne virus that infects 50–100 million people each year1. Of these infections, 200,000–500,000 occur as the severe, life-threatening form of the disease, dengue haemorrhagic fever (DHF)2. Large, unanticipated epidemics of DHF often overwhelm health systems3. An understanding of the spatial–temporal pattern of DHF incidence would aid the allocation of resources to combat these epidemics. Here we examine the spatial–temporal dynamics of DHF incidence in a data set describing 850,000 infections occurring in 72 provinces of Thailand during the period 1983 to 1997. We use the method of empirical mode decomposition4 to show the existence of a spatial–temporal travelling wave in the incidence of DHF. We observe this wave in a three-year periodic component of variance, which is thought to reflect host–pathogen population dynamics5, 6. The wave emanates from Bangkok, the largest city in Thailand, moving radially at a speed of 148km per month. This finding provides an important starting point for detecting and characterizing the key processes that contribute to the spatial–temporal dynamics of DHF in Thailand.

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