[Surveillance on the pathogen of imported Dengue fever in Henan province, 2018]

Objective: To analyze data gathered from the laboratory records related to imported Dengue cases in Henan province in 2018. Methods: Suspected Dengue cases were found out through the Dengue fever surveillance network from the National infectious Disease reporting management information system. Serum samples of suspected Dengue cases were collected while case study and tested for Dengue NS1 antigen, IgM, IgG antibodies and Dengue RNA in Henan province in 2018. According to the standardized Dengue diagnosis criteria, confirmed cases were identified under the results of testing. Dengue RNA was checked by Real-time PCR genotyping and amplification of E gene in the samples being tested, before the PCR products were sequenced and analyses of homological and phylogenetic were performed. Results: In 2018, a total of 29 cases of Dengue fever was reported in Henan province, with all of which were imported cases, mainly from Southeast Asian countries and Africa. Majority of the cases were young and middle-aged farmers under 45 years old, and the number of males was significantly higher than that of females. The imported cases were dispersed in time and space. Among the 29 Dengue reported cases, 22 cases were with NS1 antigen and/or IgM positive through testing, while 6 cases were positive by detection of the Dengue virus RNA. These 6 samples with Dengue RNA were genotyped successfully, including 3 cases of Dengue virus type 1 and 3 cases of type 2. One of the Maldives import Dengue virus type 2 samples was sequenced. Result showed that the sequence belonged to the Asian Ⅰ genotype, which was most consistently similar to the Cambodia's Dengue virus type 2 JF730046, identified in 2008. Conclusions: The incidence of imported Dengue fever cases increased significantly in Henan province in 2018, compared to that in 2017, but fortunately did not cause any local epidemics.