Spatial Circulation of Dengue Serotypes in Eastern Thailand during 2012-2015

Dengue virus infection is an epidemic infectious disease and currently a major public health problem in Thailand. The epidemiology of dengue is characterized by cyclic epidemic activity alternating between years of relatively low and high dengue incidence. The annual change of predominant serotypes was the cause of severity of the disease. This study was to determine the circulating dengue serotype by reverse transcription polymerase chain reaction (RT-PCR) during January 2012 to December 2015. A total of 527 seropositive acute samples were analyzed from dengue fever patients in eight provinces in eastern Thailand. Two hundred and forty five samples were found positive, of which 39.2%, 35.5%, 14.3% and 11.0% were affected with DENV-1, DENV-3, DENV-4 and DENV-2 respectively. From 2012 to 2013, the predominant dengue serotype was DENV-1 whereas DENV-3 and DENV-4 were predominant in 2014. There was an apparent increase in the percentage of DENV-4 from 2014 to 2015 and DENV-4 was predominant in 2015. DENV-2 was the least dengue serotype in this region. The study indicated that all four dengue serotypes were circulating in eastern Thailand and the predominant serotypes were dynamic. The identification of dengue viruses infecting the human population provides an important means of early detection of any change in the prevalence of dengue virus serology. Our study has shown the pattern of dengue virus in eight provinces of eastern Thailand from year to year and provided some insight into the dengue epidemic situation in this region. This information should be beneficial to dengue surveillance and prevention and control programs in Thailand.