Millions of cases of hand, foot, and mouth disease (HFMD) have been reported annually in mainland China since 2008. In this study, we investigated the epidemiology and etiology of an HFMD epidemic in Fujian province, which is located in subtropical southeastern China. Our study found similar epidemiological features of HFMD in southern areas of China, including seasonality and demographic distribution, as well as correlation between severity of illness and serotype. At least 22 serotypes of other enterovirus co-circulating with enterovirus 71 were found to belong to clade C4a, and those circulating with coxsackievirus A16 were associated with clades B1a and B1b.

BackgroundHand, foot, and mouth disease (HFMD) is a common contagious disease in infants; it is caused by multiple serotypes of human enterovirus (EV), which belongs to the enterovirus genus of the picornavirus family. According to sentinel surveillance, infection with EVs other than EV71 and CVA 16 have become increasingly common in recent years among HFMD patients, posing new challenges for HFMD control. This study aimed to explore the spectrum of serotypes in the other EVs (non-EV71 and non-CVA16) in Fujian province in southeastern China.Material/MethodsWe investigated 562 samples from EVs-infected HFMD patients with diagnosis confirmed by real-time RT-PCR with other EVs infection between 2011 and 2015. Nucleotide acid detection and the serotyping of the enteroviruses were also performed. The complete VP1 gene was amplified and sequenced. VP1-based phylogenetic analyses of CVA6, CVA10, CVA4, and CVA2 were also performed.ResultsAmong the samples, 22 serotypes of the other EVs, which belong to 4 species of human enterovirus A–D, were identified. Of the 22 serotypes, CVA6 (57.8%) and CVA10 (21.0%) were most common, followed by CVA4 (6.8%) and CVA2 (2.7%). The other 18 serotypes accounted for 11.7% of samples, none of which exceeded 2%. Among 47 (8.4%) samples from patients with severe HFMD, 10 serotypes were identified and most samples belonged to CVA6 (20/47), followed by CVA10 (11/47). Entire VP1 comparison revealed that overall genetic identities were 96.7%, 96.3%, 94.4%, and 94.9% among strains within CVA6, CVA10, CVA4, and CVA2, respectively.ConclusionsVP1-based phylogenetic analysis for the 4 predominant serotypes indicated various clades or sub-clades, which suggests the complex transmissions of other enteroviruses in Fujian.

This study aimed to investigate the epidemiological, clinical, and virologic characteristics of avian influenza A (H7N9) confirmed cases from two family clusters in Southeast China. Epidemiological data of the H7N9 confirmed cases and their close contacts were obtained through interviews and reviews of medical records. Of the four patients in these two family clusters, two cases had mild symptoms, one had severe symptoms, and one died. Three of the four patients had a history of exposure to live poultry or contaminated environments. The complete genome sequences of the H7N9 viruses from the same family cluster were highly homologous, and the four isolated viruses from the two family clusters exhibited the virologic features of the H7N9 virus, in terms of transmissibility, pathogenicity, host adaptation, and antiviral drug resistance. In addition, our findings indicated that the A/Fujian/18/2015 viral strain contained an additional hemagglutinin G225D substitution, which preferentially binds α2,6-linked sialic acids. The results of this study demonstrate that one family cluster was infected through common exposure to live poultry or contaminated environments, and the other was more likely to be infected through the human-to-human route.

The 1918 "Spanish" pandemic is the earliest known influenza H1N1 virus. Since then H1N1 viruses circulated between humans and animals continuously. With the increased amount of samples of H1N1 viruses and technology development, researchers have been studying how the viruses evolved. Here, we analyzed HA and NA genes of H1N1 viruses from three aspects: host distribution, geographical distribution and phylogenetic analysis. The data showed hosts were predominantly human, swine and poultry, and other hosts were mainly cat, ferret, wild bear, canine, cheetah and seal. In terms of geographical distribution, the North America and Eurasia were the main H1N1 influenza pandemic areas. Of them, the United States, China, Japan, Canada, the United Kingdom, India and Singapore were the most affected. The phylogenetic analysis of surface genes of influenza H1N1 viruses from 1918 to 2017 worldwide revealed the distribution of all avian influenza viruses (AIVs) showed a clear geographical difference, mainly concentrated in Eurasia and America. American and Eurasian swine viruses might be the ancestors of the 2009 pandemic virus' HA and NA genes. Swine influenza viruses played an important role in the spread of influenza viruses across species. To our knowledge, this is the first large-scale phylogenetic analysis of HA and NA genes of influenza H1N1 viruses worldwide until now. Our findings further emphasize the importance of surveillance of the genetic diversity of influenza H1N1 viruses in different hosts and raised more concerns about the long-time monitoring.