Epidemiological Investigation Of Influenza In Children And Clinical Application Of Rapid Influenza Virus Detection

Part 1 Application of fluorescent immunoassay lateral flow technology in pathogen diagnosis in children with influenza-like illnessObjective:To evaluate the clinical application value of the fluorescent immunoassay lateral flow technology in detecting influenza virus.Methods:578 nasopharyngeal swabs were collected from children with influenza-like illness(ILI)from November 2015 to February 2016 and were detected for influenza virus A and B antigens by Sofia influenza A+B FIA(fluorescent immunoassay lateral flow technology).The results were compared with that of direct immune-fluorescence assay and the samples with inconsistent results by the two methods were verified by RT-PCR.Result:The results indicated that influenza virus antigen detection by Sofia influenza A+B FIA was highly consistent with the results of direct immune-fluorescence assay.The sensitivity and specificity for detecting influenza virus A were 100%and 96.53%,the specificity raised to 99.6%after verified by RT-PCR because 16 of 18 inconsistent samples were positive by RT-PCR.For influenza B the sensitivity and specificity were 97.83%and 97.04%,and raised to 98.4%and 99.8%after verified by RT-PCR with 15 of 17 inconsistent samples were positive by RT-PCR.Compared with influenza virus B,more children were infected with influenza virus A that course more serious clinical symptom.Conclusion:Influenza is a significant cause of children respiratory infections.Sofia Influenza A+B FIA is a rapid and easy antigen-detecting assay for influenza virus A and B,which has high concordance rate with direct immune-fluorescence assay that can be used for screening and diagnosis of influenza virus A and B.Part 2 Epidemiological investigation of influenza virus infection in children in HunanObjective:To study the distribution and clinical characteristics of influenza virus infection in children in Hunan Province to provide evidence for the prevention and treatment of influenza.Methods:2715 cases of suspected influenza patients enrolled in the study group in 7 hospitals of Hunan Province,;all patients were collected clinical data,including gender,age,exposure history,epidemiology of influenza vaccination history,clinical symptoms and laboratory data.All the children were selected to collect nasopharyngeal swabs.The 7 research centers before the start of the study were to train the nasopharyngeal swabs,and fill in the data.Before the specimen was collected,the consent of the family members of the children and the approval of the hospital ethics committee were obtained.Results:1.Among 2715 cases of suspected influenza,influenza virus was detected in 1386 cases(51%),influenza A virus was detected in 305 cases(n=22%),influenza B virus was detected in 1077 cases(77.7%),influenza A virus and influenza B virus were detected in in 4 cases(2).Boys accounted for 61.5%(853/1386),girls accounted for 38.5%(533/1386),Chi 2=38.344,P=0.000,influenza virus was detected in boys more than that in girls.2.less than the 6 months age(<6m)52 cases(positive rate 20.7%),6 months age to 1 year(6m?)83 cases(positive rate 20.9%),196 cases of children aged 1?2 years(ly?)(detection rate 44.6%),639 cases of children aged 2?6 years(2y?)(detection rate 70.6%),416 cases were detected(6?14 years(6y?14y)old children 57.3%).After statistical analysis,suggesting that there are differences in the age distribution.3.619 cases(44.7%)of children with acute respiratory infection symptoms or fever symptoms before the onset of contact.144 children had been vaccinated against influenza,flu unvaccinated children are more likely to be infected with influenza.4.All influenza positive children had fever,855 influenza A cases and 853 influenza B cases had cough.There were influenza A 152 cases(51.2%)and influenza B 613 cases(59.3%)suffer nasal congestion and runny nose.613 cases suffer sore throat(influenza A 49 cases(16.5%),influenza B 249 cases(24.1%)).There were influenza A 7 cases(2.4%),influenza B 20 cases(1.9%)suffer wheezing and short of breath.Febrile convulsion was found in 11 influation A cases and 10 influation B cases and vomiting and/or diarrhea were found in 21 influation A cases and 36 influation B cases.Compare with those of influenza B,the white blood cell and neutrophil count in the children with influenza A were higher,but there was no significant difference between the two groups.Conclusion:1.Influenza virus is one of the important pathogens of respiratory tract infection in children in Hunan.Boys are more likely to be infected with influenza than girls;2 to 6 years of age and children aged between 6 and 14 are more likely to become infected with influenza;2.The symptoms of influenza A cases had more complex symptoms than those of influenza B.Influenza A cases have higher white blood cell count and neutrophils.3.Flu unvaccinated children are more likely to be infected with influenza.Part 3 A preliminary study on the disappearance time of influenza virus antigenObjective:To investigate the antigen clearance time,time to symptom disappearance,and the association between them using immunofluorescence assay for dynamic monitoring of influenza virus antigen in children with influenza.Methods:A total of 1063 children suspected of influenza who visited the Hunan People's Hospital from March to April,2016 were enrolled The influenza A/B virus antigen detection kit(immunofluorescence assay)was used for influenza virus antigen detection.The children with positive results were given oseltamivir as the antiviral therapy and were asked to re-examine influenza virus antigen at 5,5-7,and 7-10 days after onset.Results:Of all children suspected of influenza,560(52.68%)had an influenza virus infection.A total of 215 children with influenza virus infection were followed up.The clearance rate of influenza virus antigen was 9.8%(21 cases)within 5 days after onset.The cumulative clearance rate of influenza virus antigen was 32.1%(69 cases)within 5-7 days,and 98.1%(211 cases)within 7-10 days after onset.Among these children,6 children(2.8%)achieved the improvement in clinical symptoms within 3 days after onset.The cumulative rate of symptom improvement was 84.7%(182 cases)within 3-5 days after onset,and almost 100%achieved the improvement after 5 days of onset.Conclusions:The time to improvement in symptoms after treatment is earlier than antigen clearance time.Almost all of the children achieve influenza virus antigen clearance 7-10 days after onset.Therefore,it is relatively safe for children to go back to school within 7-10 days after onset when symptoms disappear.