ABSTRACT
disease prevalent in all provinces of Thailand. This study was to determine the circulating dengue serotypes by reverse transcription polymerase chain reaction (RT-PCR). A total of 1116 seropositive acute samples were analysed from DF/DHF patients in five provinces of northern Thailand (Chiangmai, Lampang, Lamphun, Mae Hong Son and Phrae) during the period January 2002 to December 2006. Five hundred and fifty-nine samples were found positive, of which 47.2%, 30.6%, 18.4% and 3.8% were affected with DENV-2, DENV-1, DENV-4 and DENV-3 respectively. From 2002 to 2005, the predominant dengue serotype was DENV-2, whereas DENV-1 was predominant in 2006. There was an apparent increase in the percentage of DENV-4 from 2005 to 2006. Our results indicated that all four dengue serotypes were circulating in this region and the annual change of predominant serotypes was the cause of the severity of the disease.
