Pathogenic characteristics of hand, foot and mouth disease in Shaanxi Province, China, 2010-2016.

Hand, foot, and mouth disease (HFMD) is a common childhood illness caused by enteroviruses. We analyzed the pathogenic characteristics of HFMD in Shaanxi province, China, during 2010-2016. Clinical samples were collected from HFMD cases. Real-time PCR and RT-PCR were used to identify the enterovirus(EVs) serotypes. Viral RNA sequences were amplified using RT-PCR and compared by phylogenetic analysis. Descriptive epidemiological methods were used to analyze. A total of 16,832 HFMD positive cases were confirmed in the laboratory. EV-A71 and CV-A16 were the main pathogens in 2010. EV-A71 was the dominant pathogen in the periods of 2011 to 2012 and 2014, 2016. In 2013 and 2015, other EVs increased greatly, in which CV-A6 was the predominant pathogen. EV-A71 was more frequently detected in deaths and severe cases. Phylogenetic analysis revealed that EV-A71 belonged to the C4a evolution branch of C4 sub-genotype and CV-A16 belonged to the B1a or B1b evolution branch of B1 sub-genotype, whereas CV-A6 strains were assigned to D2 or D3 sub-genotype. The pathogen spectrum of HFMD has changed in 7 years, and the major serotypes EV-A71, CV- A16 and CV- A6 alternated or co-circulated. Long-term surveillance and research of EVs should be strengthened for the prevention and control of HFMD.

Multiple genotypes of Echovirus 11 circulated in mainland China between 1994 and 2017.

Echovirus 11 (E-11) is one of the most frequently isolated enteroviruses causing meningitis and other diseases such as hand, foot, and mouth disease (HFMD) and acute flaccid paralysis (AFP). Fifty-nine newly determined E-11 VP1 sequences from the China AFP and HFMD surveillance network and 500 E-11 VP1 sequences obtained from the GenBank database, which were associated with 12 categories of diseases, were screened for phylogenetic analysis. Based on the standard method of genotype classification, E-11 strains circulated worldwide were reclassified into six genotypes as A, B, C, D, E, and F, in which genotype F is newly divided, and genotypes A and C are further divided into A1-5 and C1-4 by this research, whereas genotype D was still divided into D1-5 as in a previous study of Oberste et al. Sub-genotype A1 was the predominant sub-genotype in mainland China between 2008-2017, whereas sub-genotype D5 was the predominant sub-genotype circulated outside China from 1998-2014. However, genotype and sub-genotype spectra showed statistical significance among AFP and HFMD cases (χ2 = 60.86, P < 0.001), suggesting that different genotypes might have a tendency to cause different diseases. Strengthening the surveillance of E-11 might provide further information about pathogenic evolution or specific nucleotide mutation associated with different clinical diseases.