[Observation on intestinal viral shedding time of hand, foot and mouth disease induced by coxsackievirus A6]

Objective: To observe the intestinal viral shedding time in patients with hand, food and mouth disease (HFMD) induced by coxsackievirus A6 (CA6). Method: Throat swab specimens and stool specimens of HFMD children were collected from those admitted to Hangzhou Children's Hospital between May and October 2015, while fluorescence quantitative PCR was used to detect the viral load.Eeighteen cases of HFMD children were followed up, who were confirmed as CA6 infection via laboratory tests.Stool specimen was collected every 4-7 days, and fluorescence PCR was used for virus nucleic acid detection until the stool viral nucleic acids of infected children turned to be negative.The intestinal virus shedding time of CA6-infected HFMD was compared with the intestinal virus shedding time of 65 children with enterovirus 71 (EV71) infection and 44 children with coxsackievirus A16 (CA16) infection of the previous studies (from May to September 2012). Result: The median stool viral load was 25×10(5) copies/ml (55×10(4) copies/mL, 9×10(6) copies/ml) in CA6-infected children.The numbers of stool virus nucleic acid turning negative were 0 case, 4 cases, 9 cases, 3 cases and 2 cases in 18 children at 1st, 2nd, 3rd, 4th, 5th weeks. At 5th week, the stool virus nucleic acid of children in CA6 group all turned to be negative.The positive rates of stool virus nucleic acid in EV71 group and CA16 group at the 5th week, however, were 31% and 27% respectively.There were statistically significant differences in distribution of positive rate of stool virus nucleic acid between CA6 infected children with EV71 and CA16 infected children (χ(2)=13.894, 10.698, P<0.05). Conclusion: The longest intestinal virus shedding time for CA6-infected HFMD children was 5 weeks, which is obviously shorter than that of EV71- infected children and CA16-infected children.

[Genotype distribution of human enteroviruses isolated from swage in Shanghai during year 2013-2014]

Objective: To explore the time and genotype distribution of human enterovirus (HEV) isolated from sewage in Shanghai in 2013-2014. Methods: One sewage sample each was collected from two local sewage plants located in Minhang District and Jiading District on the same day at the day 24-28 of every month from 2013 to 2014. Each sample weighed 1 L. The specimens were concentrated by anionic membrane absorption, eluted with beef extract solution, and then used to inoculate RD, HEp-2, and L20B cell lines. A total of 249 enterovirus strains were isolated from sewage samples during the study period, including 185 non-polio enterovirus (NPEV) and 64 poliovirus (PV) strains, which were identified as vaccine strains. RT-PCR and Sanger sequencing were performed to identify HEV genotypes. Homologous analysis of VP1 sequences was conducted using BioEdit (version 7.0.0). Phylogenetic analysis was performed using the neighbor-joining method based on the alignment of VP1 gene sequences using MEGA (version 4.0.2). Results: Among 185 NPEV strains, 178 strains were successfully sequenced and classified into 15 genotypes, including coxsackievirus group B (CVB) 2, 3, and 5; enteric cytopathic human orphan (ECHO) virus 1, 3, 6, 7, 11, 13, 19, 20, 24, 25, and 30; and coxsackievirus group A 4. CVB5 and ECHO6 genotypes accounted for 33.5% (56 strains) and 24.9% (43 strains) of NPEV isolates, respectively. During the study period, HEV isolates were mainly isolated in summer and autumn in Minhang District. ECHO6 strains were frequently isolated from June 2013 to July 2014. Thereafter, the number of ECHO6 strains gradually reduced in the second half of 2014. CVB5 strains demonstrated scattered distribution from 2013 to the first half of 2014 and gradually increased in the second half of 2014. The distribution of ECHO6 and CVB5 strains in Jiading District was similar to that in Minhang District. In 2013-2014, CVB5 strains comprised C6 and C8 subgenotypes, which belong to two transmission chains and show large differences compared with foreign strains isolated during the same period. ECHO6 strains comprised C6, C8, and D9 subgenotypes, which belong to three transmission chains. Moreover, ECHO6 subgenotype D9 was a dominant subgenotype in Shanghai, with broad geographical distribution both at home and abroad. Conclusion: Poliovirus was identified as a vaccine strain in environmental surveillance from June 2013 to April 2014 in Shanghai. Several transmission strains of ECHO6 and CVB5 were identified, which were the dominant serotypes.