RESUMEN
Objective@#To elucidate the epidemiological and etiological features of a local outbreak of dengue fever (DF) in Taijiang district in Fuzhou, Fujian province in 2017, and speculate possible viral source based on phylogenetic analysis.@*Methods@#The clinical and demographic data of cases were collected through field investigation and the outbreak was characterized epidemiologically by descriptive method. The patient′s serum were collected and the adult mosquitoes were captured by anti-mosquito double-net method for the laboratorial test and viral isolation. The viral isolates were typed by real-time fluorescent RT-PCR and their full length of viral envelope (E) genes were amplified by RT-PCR and sequenced. The E gene sequences obtained in this study, together with the reference sequences, were used for the phylogenetic analysis.@*Results@#A total of 13 cases of autochthonous DF were confirmed in the outbreak. All cases presented obvious clinical manifestations and clustered spatially and temporally. The Breteau Index (BI) of mosquito larva density was the highest in epidemic foci of Xingang street and was relatively low in surrounding areas. Four DENV-1 strains, three from patients and one from the captured adult Aedes albopictus, were isolated and identified by real-time RT-PCR. Full length E gene sequences of the four isolates were completely identical and phylogenetic analysis showed that the isolates were genetically closest to the strain (GenBank No. KT825033) from Vietnam in 2014, rather than the DENV-1 strains found in Fujian previously.@*Conclusions@#The DF outbreak occurred in Fuzhou in 2017 was caused by DENV-1 which was imported possibly from somewhere outside of Fujian province and subsequently led to local DF transmission in human via the mosquito Aedes albopictus.
RESUMEN
Objective@#To study the etiological characteristics of an imported Chikungunya fever (CHIK) epidemic in Fujian province in 2018.@*Methods@#Serum samples collected at different days after the onset of the two CHIK cases were detected by real-time RT-PCR and ELISA. Structural protein E1 gene was amplified by RT-PCR and sequenced for nucleotide characteristics analysis and phylogenetic tree analysis.@*Results@#RNA of Chikungunya virus (CHIKV) was detected in the 4 serum samples collected on the first 5 days of the disease, and the earliest IgM antibodies were detected in specimens on the 5th day of the disease, however, IgG antibodies were only detected in specimen on 10th day. Compared with the S27-African prototype strain, 12 mutant points were found in the amino acids of E1 genes in this study. The E1 genes of the two CHIK cases were exactly the same, and they were closest to the evolutionary relationship with the strain isolated in the Philippines in 2014. Their genotype was Asian genotype.@*Conclusions@#This epidemic was confirmed to have been imported from the Philippines after the infection with the Asian genotype CHIKV, which suggests that Fujian province should strengthen the monitoring of persons entering from the CHIK epidemic area, so as to prevent imported cases from causing local outbreaks.