We thank Dr Viroj Wiwanitkit for his comments on our preliminary assessment of the age and sex distribution of the human cases with avian influenza A(H7N9) virus infection. To clarify, we posed three scenarios which could possibly explain the preponderance of cases among elderly men reported through China’s surveillance system: (1) differential exposure due to gender-associated practices and norms, e.g. more high-risk behaviours among elderly men; (2) differential clinical course post-exposure/infection, e.g. given similar exposures, elderly men have a more severe outcome relative to other age–gender groups; and (3) differential health care-seeking/access behaviour favouring selection of elderly men, e.g. elderly men accessing health care more than other age-gender groups.

Since 31 March 2013, the government of China has been notifying the World Health Organization (WHO) of human infections with the avian influenza A(H7N9) virus,1 as mandated by the International Health Regulations (2005).2 While human infections with other subgroups of H7 influenza viruses (e.g. H7N2, H7N3, and H7N7) have previously been reported,3 the current event in China is of historical significance as it is the first time that A(H7N9) viruses have been detected among humans and the first time that a low pathogenic avian influenza virus is being associated with human fatalities.4 In this rapidly evolving situation, detailed epidemiologic and clinical data from reported cases are limited—making assessments challenging—however, some key questions have arisen from the available data. Age and sex data, as one of the first and most readily available data, may be an important proxy for gender-specific behaviours/conditions and an entry point for response.5,6 Here, we describe the age and sex distribution of the human cases of avian influenza A(H7N9) to better inform risk assessments and potential next steps.

Currently,three predominant subtypes of influenza virus are prevalent in pig populations worldwide:H1N1,H3N2,and H1N2.European avian-like H1N1 viruses,which were initially detected in European pig populations in 1979,have been circulating in pigs in eastern China since 2007.In this study,six influenza A viruses were isolated from 60 swine lung samples collected from January to April 2011 in eastern China.Based on whole genome sequencing,molecular characteristics of two isolates were determined.Phylogenetic analysis showed the eight genes of the two isolates were closely related to those of the avian-like H1N1 viruses circulating in pig populations,especially similar to those found in China.Four potential glycosylation sites were observed at positions 13,26,198,277 in the HA1 proteins of the two isolates.Due to the presence of a stop codon at codon 12,the isolates contained truncated PB1-F2 proteins.In this study,the isolates contained 591Q,627E and 701N in the polymerase subunit PB2,which had been shown to be determinants of virulence and host adaptation.The isolates also had a D rather than E at position 92 of the NS1,a marker of mammalian adaptation.Both isolates contained the GPKV motif at the PDZ ligand domain of the 3' end of the NS1,a characteristic marker of the European avian-like swine viruses since about 1999,which is distinct from those of avian,human and classical swine viruses.The M2 proteins of the isolates have the mutation (S31N),a characteristic marker of the European avian-like swine viruses since about 1987,which may confer resistance to amantadine and rimantadine antivirals.Our findings further emphasize the importance of surveillance on the genetic diversity of influenza A viruses in pigs,and raise more concerns about the occurrence of cross-species transmission events.

Objective To evaluate the diagnostic value of detection of IgM antibodies to EV71-infection patients,and compared characterisation of RT-PCR,IgM capture ELISA and neutralization test.Methods Virus RNA,neutralization titer and IgM antibody in 115 EV71-infection patients were detected by EV71 real-time RT-PCR kit( EV71-PCR kit),neutralization test,and EV71 IgM-capture ELISA kit (EV71-IgM kit),respectively.Results Using EV71-IgM kit,the detection rate was 80.9％ (93/115,95％ CI:72.5-87.6) among the 115 EV71-infection patients,and was 2.6％ among the 228 healthy children.Simultaneously,sera collected after 1-2 day of disease onset showed an IgM positivity of 70.4％ (38/ 54).The positive rate of EV71-PCR among these patients was 82.6％ (95/115,95％ CI:74.4-89.0),so there was no statistically significant differences between it and EV71-IgM kit.In addition,the detection rate in EV71-infection patients could increase to 92.2％ by combined detection of EV71-PCR and EV71-IgM kit.Conclusion EV71-IgM kit was a rapid and valuable way for the early diagnosis of EV71 infection,and could significantly improve detection rate for EV71 infection by combining with EV71-PCR kit.

ObjectiveTo investigate norovirus infection status and indentify its epidemiological characteristics and genotype distribution in infantile viral diarrhea in Jiangsu.MethodsFour hundred and ninety-eight fecal specimens of infantile virus diarrhea cases were collected from Suzhou Children's hospital and Nanjing Children's hospital in 2010.Norovirus genegroup were detected by real-time RT-PCR,and genetype were determined by sequence analysis.Results Among all fecal specimens,2 (0.4％) cases were positive for norovirus G Ⅰ,and 190 (38％) cases for G Ⅱ.Nucleotide sequence analysis revealed that in the 2 samples for G Ⅰ,one strain was G Ⅰ 1 and another was G Ⅰ 3.Twenty-one strains were belonged to G Ⅱ 4 and 2 strains were G Ⅱ 3 in the 23 samples for G Ⅱ.ConclusionAs one of the most important pathogens causing infantile viral diarrhea in Jiangsu province,subtype G Ⅱ 4 was the main epidemic strain of norovirus,meanwhile other genotypes also existed.

Objective To estimate the rates due to influenza-associated-excess-hospitalization in children aged 0-14 years in Wuxi city,Jiangsu province in 2005-2010. Methods We collected data on hospitalization due to influenza,pneumonia and other respiratory diseases from fourteen 2nd level or above hospitals in Wuxi,as well as data on influenza virological surveillance in southern China to fit the negative binomial regression models,to estimate the rate on influenza-associated-excess hospitalization. Results During 2005-2010,an average annual hospitalization rate appeared as 91.6‰(79.2‰-99.3‰). Among the total hospitalization eases,respiratory diseases accounted for 54.2%,while both influenza and pneumonia accounted for 38.1%. The average annual influenza-associated-excess-hospitalization rates due to influenza and pneumonia appeared as 1.28‰(95%CI:0.29‰-4.84‰),while 2.18‰(95%CI:0.61‰-6.79‰) due to respiratory diseases. In 2009,A(H1N1)pdm induced influenza pandemic caused 993 excess hospitalizations due to influenza/pneumonia and 1 042 excess hospitalizations due to respiratory diseases,with rates as 1.14‰ and 1.20‰ respectively. Conclusion Both seasonal and pandemic A(H1N1)pdm influenza caused considerable burden on hospitalization in children aged 0-14 years in Wuxi.

OBJECTIVETo estimate the rates due to influenza-associated-excess-hospitalization in children aged 0-14 years in Wuxi city,Jiangsu province in 2005-2010.

METHODSWe collected data on hospitalization due to influenza, pneumonia and other respiratory diseases from fourteen 2nd level or above hospitals in Wuxi, as well as data on influenza virological surveillance in southern China to fit the negative binomial regression models, to estimate the rate on influenza-associated-excess hospitalization.

RESULTSDuring 2005-2010, an average annual hospitalization rate appeared as 91.6‰ (79.2‰ -99.3‰). Among the total hospitalization eases, respiratory diseases accounted for 54.2%, while both influenza and pneumonia accounted for 38.1%. The average annual influenza- associated-excess-hospitalization rates due to influenza and pneumonia appeared as 1.28‰ (95% CI:0.29‰ -4.84‰), while 2.18‰ (95% CI:0.61‰ -6.79‰) due to respiratory diseases. In 2009, A (H1N1) pdm induced influenza pandemic caused 993 excess hospitalizations due to influenza/pneumonia and 1 042 excess hospitalizations due to respiratory diseases, with rates as 1.14‰ and 1.20‰ respectively.

CONCLUSIONBoth seasonal and pandemic A(H1N1)pdm influenza caused considerable burden on hospitalization in children aged 0-14 years inWuxi.

Adolescent ; Child ; Child, Preschool ; China ; epidemiology ; Female ; Hospitalization ; statistics & numerical data ; Humans ; Infant ; Infant, Newborn ; Influenza, Human ; epidemiology ; Male