Concurrent infections by two dengue virus serotypes among dengue patients in Taiwan

The co-circulation of multiple dengue virus serotypes in the same region has been reported in several countries in Southeast Asia as well as in Central and South America for decades. Although outbreaks involving more than one serotype of dengue virus have been reported in Taiwan since 1987, concurrent infection in the same individual by multiple serotypes of dengue virus have never been identified. Using a modified multiplex reverse transcription-polymerase chain reaction assay, we detected and determined the serotypes of 21 dengue patients during an outbreak in southern Taiwan in 2000. While either dengue type 2 or type 3 virus was found in most cases, 2 of the 21 cases were concurrent infections by both dengue type 2 and dengue type 3 viruses. This was further confirmed by sequence analysis of the amplified products. This study reports for the first time that concurrent infections occur in Taiwan, and suggests that future virologic surveillance of dengue outbreak in Taiwan should take this into consideration.