Double dengue serotypes in asymptomatic populations living in an area of Thailand endemic for dengue hemorrhagic fever

Abstract

Dengue virus infection remains a major health problem worldwide. Understanding dengue infection and characterizing circulating viruses are essential for disease prevention and control as well as vaccine development. In this study, we aimed to identify dengue virus in healthy people living in an area endemic for dengue disease. Blood samples were collected from 52 healthy local subjects living in a dengue-endemic area of Thailand. Viral RNA was detected using a nested reverse transcription polymerase chain (RT-PCR) that amplified the E gene. Phylogenetic trees were constructed by the neighbor-joining method using MEGA6.06. Dengue virus was detected in 5 of 52 samples (9.62%). Double dengue virus infection (Den 1&4 and Den 3&4) was found in two samples. Sequence analysis of the viruses showed that dengue serotype 1 belonged to sylvatic genotype. A mix of genotype I and II was found in a dengue serotype 3 sample while all dengue virus serotype 4 in this study belonged to genotype II. These preliminary results may provide better understanding of dengue infection and viral transmission between populations and mosquitoes. Therefore, it could be used for epidemiological studies and control of dengue hemorrhagic fever in the future.