RESUMO
BACKGROUND: Echovirus 30 (E-30) has been investigated and reported worldwide and is closely associated with several infectious diseases, including encephalitis; myocarditis; and hand, foot, and mouth disease. Although many E-30 outbreaks associated with encephalitis have been reported around the world, it was not reported in northwest China until 2015. METHODS: The clinical samples, including the feces, serum, throat swabs, and cerebrospinal fluid, were collected for this study and were analyzed for diagnosis. E-30 was isolated and processed according to the standard procedures. The epidemiological and phylogenetic analysis were performed to indicate the characteristics of E-30 outbreaks and phylodynamics of E-30 in China. RESULTS: The E-30 outbreaks affected nine towns of Gansu Province in 2015, starting at a school of Nancha town and spreading to other towns within 1 month. The epidemiological features showed that children aged 6-15 years were more susceptible to E-30 infection. The genotypes B and C cocirculated in the world, whereas the latter dominated the circulation of E-30 in China. The genome sequences of this outbreak present 99.3-100% similarity among these strains, indicating a genetic-linked aggregate outbreak of E-30 in this study. Two larger genetic diversity expansions and three small fluctuations of E-30 were observed from 1987 to 2016 in China, which revealed the oscillating patterns of E-30 in China. In addition, the coastal provinces of China, such as Zhejiang, Fujian, and Shandong, were initially infected, followed by other parts of the country. The E-30 strains isolated from mainland of China may have originated from Taiwan of China in the last century. CONCLUSION: The highly similar E-30 genomes in this outbreak showed an aggregate outbreak of E-30, with nine towns affected. Our results suggested that, although the genetic diversity of E-30 oscillates, the dominant lineages of E-30 in China has complex genetic transmission. The coastal provinces played an important role in E-30 spread, which implied further development of effective countermeasures. This study provides a further insight into the E-30 outbreak and transmission and illustrates the importance of valuable surveillance in the future.
RESUMO
We used molecular-biology methods to identify the pathogens that caused an outbreak of viral encephalitis in Guazhou (Gansu province, China)during June-August 2015.We also undertook molecular characterizations of these pathogens. A total of 132samples(14cerebrospinal fluid(CSF)samples;25throat swabs;66serum samples;27fecal samples)were collected from 74 patients during the outbreak of viral encephalitis. For CSF and serum samples, enzyme-linked immunosorbent assay immunoglobulin-M tests were undertaken to detect Japanese encephalitis viruses, enteroviruses, herpes simplex viruses, mumps viruses, and adenoviruses. Real-time polymerase chain reaction was done to detect enteroviruses(including coxsackievirus A16 and enterovirus 71) and the RNA of human adenoviruses. Then, viral isolation was carried out using HEp-2 and RD cells, and the entire VP1 region of positive viral isolates was amplified and sequenced. Finally, molecular characterizations of these pathogens were completed. Seventy two samples were identified as enteroviruses from 132 samples. Among them,71 were identified as echovirus(ECHO)30using enterovirus molecular typing. Japanese encephalitis viruses,herpes simplex viruses, mumps viruses, and adenoviruses were not detected.ECHO30 was isolated from 46 samples out of 29 patients.Similarities in nucleic acids among these ECHO30 isolates were 99.2%-100.0%.ECHO30 from Gansu province and other ECHO30 strains isolated in China since 2011 belonged to a same evolutionary branch.ECHO30 was the pathogen that caused the outbreak of viral encephalitis in Guazhou in 2015.ECHO30 from and Gansu province and ECHO30 isolated in China since 2011 belonged to the same evolutionary branch.