Laboratory-based dengue surveillance in Taiwan, 2005: a molecular epidemiologic study.

We present the results of laboratory-based dengue surveillance in Taiwan for 2005. A phylogenetic study showed that multiple dengue epidemics were caused by three different imported dengue virus (DENV) strains. A strain of DENV-3 (genotype I) imported from the Philippines first appeared in the southern part of Kaohsiung City and later spread to Kaohsiung County from August to December, which resulted in 77 cases of dengue. Another strain of DENV-3 (genotype II) imported from Vietnam first appeared in the central part of Kaohsiung City and later spread to Kaohsiung County from September to December, which resulted in 35 cases of dengue. A strain of DENV-2 (American/Asian genotype) imported from Vietnam first appeared in Tainan City and later spread to Kaohsiung City/County from October to December, which resulted in 60 cases of dengue. This study provides molecular epidemiologic evidence that most dengue in Taiwan is caused by imported strains of the virus.