Dengue Hemorrhagic Fever, Uttaradit, Thailand

摘要

To the Editor: Dengue hemor-rhagic fever (DHF) has been recog-nized as a disease of young children inthe past. Three decades ago mostreported case-patients in Thailandwere 3–6 years of age (1). Increasingevidence shows that the age groupmost affected is changing (2). Wereport evidence that in Uttaradit,Thailand, the predominant age ofthose who acquire DHF has increasedby at least 2 years during the 1990s.Uttaradit is a province in the north-ern part of Thailand. DHF is endemicin Uttaradit, as it is in most parts ofthe country. Between 1992 and 2001,three major outbreaks of DHFoccurred, in 1993, 1998, and 2001.The number of DHF cases report-ed to the Provincial Health Officefrom January 1992 to December 2001(classified by age groups) was used asthe estimated annual DHF incidence.Case definition and categorizationfollowed the International StatisticalClassification of Diseases and RelatedHealth Problems (ICD-10). DHF cat-egories reported in this study includedboth DHF without shock and thedengue shock syndrome (the numberof cases and deaths combined).Dengue fever, a milder disease mani-festation, was not included.The age distribution of DHF casesshowed that, in the 1993 epidemic,children 5–9 years of age had thelargest proportion of cases, whereas in2001, the peak age of those infectedwas 10–14 years. The transitionalstage (mean age 11.3 years) wasobserved in 1998.During the observed period, theannual mean age of DHF case-patients ranged from 8.4 to 15.1 years.Despite some fluctuation, the meanage of DHF case-patients was 10 years