Ito Mikako, Yamada Ken-Ichiro, Takasaki Tomohiko, Pandey Basu, Nerome Reiko, Tajima Shigeru, Morita Kouichi, Kurane Ichiro
Department of Virology 1, National Institute of Infectious Disease, Tokyo, Japan.
J Travel Med. 2007 Jul-Aug;14(4):233-44. doi: 10.1111/j.1708-8305.2007.00130.x.
Molecular epidemiology of dengue viruses in endemic countries have been reported, but few were reported on the imported dengue cases among travelers. We analyzed dengue viruses isolated from imported dengue cases in Japan who were infected while traveling in endemic regions of the world.
We sequenced the complete envelope (E) gene of 33 dengue virus strains isolated from patients returning from Asia, Oceania, South Pacific islands, and South America to Japan where no domestic dengue virus infection occurs. We then performed phylogenetic analysis to define the geographic origin of isolated viruses. Moreover, we compared the genomes of isolated dengue viruses with those of the strains already deposited in the GenBank database.
The isolates are clustered into expected genotypes, confirming that the viruses originated from the visited countries. When patients visited more than one country during a single trip, the countries where the infection occurred were also determined for four of the six patients. There were three isolates, which were different genotypes from those previously isolated in visited countries.
The study demonstrates that many dengue virus strains are introduced into Japan and that phylogenic analysis of isolated dengue viruses is a unique technique to determine the countries where infection occurred. Travelers carry viruses and provide important and unique information for clarifying dengue virus trait and its dissemination.
已有关于登革热病毒流行国家分子流行病学的报道，但关于旅行者中输入性登革热病例的报道较少。我们分析了从在世界流行地区旅行时感染的日本输入性登革热病例中分离出的登革热病毒。
我们对从亚洲、大洋洲、南太平洋岛屿和南美洲返回日本（日本无本土登革热病毒感染）的患者中分离出的33株登革热病毒株的完整包膜（E）基因进行了测序。然后进行系统发育分析以确定分离病毒的地理来源。此外，我们将分离出的登革热病毒基因组与已存入GenBank数据库的毒株基因组进行了比较。
分离株聚为预期的基因型，证实病毒源自所访问的国家。当患者在单次旅行中访问多个国家时，还确定了6名患者中4名患者的感染发生国家。有3株分离株，其基因型与之前在所访问国家分离出的不同。
该研究表明，许多登革热病毒株被引入日本，对分离出的登革热病毒进行系统发育分析是确定感染发生国家的独特技术。旅行者携带病毒，为阐明登革热病毒特征及其传播提供了重要且独特的信息。
