Detection and management of an imported case of Chikungunya fever in Henan

ObjectiveTo understand the epidemiological and etiological characteristics of an imported Chikungunya fever case occurred in Huixian county of Henan province in August 2019 and provide evidence for the prevention and control of the further spread.

MethodsThe serum samples of the case, person with co-exposure and contacts as well as mosquito samples were detected with real-time fluorescence quantitative RT-PCR and the virus isolation was conducted, E1 gene of the isolate was sequenced and analyzed by Clustal X and MEGA 7.0. Epidemiological investigation was conducted, and prevention and control measures were taken according to related technical guidelines.

ResultsThe serum sample of the case was positive for nucleic acid of Chikungunya virus. The virus isolate (GenBank No. MN432879) belonged to ECSA genotype of Chikungunya virus. In E1 section, the isolate shared 100% nucleotide/amino acid homology of MN432879 with an imported strain (GenBank No. MG912993) in Zhejiang in 2017, and shared 99.4% nucleotide homology and 99.8% amino acid homology with an imported strain (GenBank No. MG925665) isolated in Henan. There was one case with co-exposure and three contacts, all of them showed no clinical manifestations of Chikungunya fever. The breteau index of the epidemic point declined from 9.5 in the first surveillance to 3.2 in the third surveillance and remained at a low level. Mosquito samples were negative for nucleic acid of Chikungunya virus.

ConclusionThe imported Chikungunya fever case in Huixian county of Henan was caused by ECSA genotype Chikungunya virus, no further spread occurred in this area.