Clinical Study On Community-acquired Adult Infection Of Influenza Virus

Background: The influenza virus is one of the most common respiratory virus, itis divided into A, B and C three types, and influenza virus A is divided into severalsubtypes.At present, many infected with human influenza virus subtypes have beenfound, such as H1N1, H3N2, H5N1, and so on.Influenza virus’s host is numerous andwidely distributed in nature(birds, pigs, people, horses, and marine mammals are thehost).By a variety of ways,including air droplets and direct contact, influenza virus canspread from person to person, animal infection can also be transmitted to humans,people are generally susceptible, and the influenza virus is easy to mutate through theform of antigenic drift and antigenic shift.In the human history, the influenza virusoutbreaks frequently and dangerously, there are four pandemics in the20th century, andjust more than10years time after entering the21st century, the global epidemic of theinfluenza virus are two times (avian influenza H5N1and novel H1N1).Therefore, thedetection, monitoring and prevention of influenza virus is essential. Currently, themethods for detection of influenza virus are:(1) viral cultures: It is considered the "goldstandard",traditional viral culture method can obtain strains and provide a basis forfurther research, but its culture period is longer, and it often requires a few days or evena few weeks.It isn’t suitable for the needs of early diagnosis and outbreak responsediagnostic, it is difficult to achieve the requirements of rapid detection andidentification when influenza outbreaking.(2) serological test: It can detect the specificantibodies IgM and IgG and antibody levels, but it’s often used for epidemiological andretrospective diagnosis.(3) immunofluorescence assay: There are direct immunoflu-orescence assay and indirect immunofluorescence assay. This method has a shortdetection period, good sensitivity and specificity, but the sample requires higher, and itneeds expensive fluorescent microscope, and is best observed and analysed by professionals.(4) enzyme immunoassay: It’s an important technology in theimmunoassay markers, it’s easy to operate and fast.(5) gold immunochromatographyassay: simple operation, a short period of time (usually10-30minutes) to get theresults,it can detect influenza virus rapidly in the clinically.(6)polymerase chainreaction: it is one of the widely used molecular biology detection techniques, goodspecificity, but easily contaminated. Now there are RT-PCR (real-time PCR) and othertechnologies.In our country, the influenza virus is widely popular as a seasonalepidemic, Dalian is located in northeast of China, winter is the peak season of influenzavirus.Objective: To describe the clinical features of adult community-acquired influenzavirus infection.Methods: The experimental group of62cases and the healthy control group of33cases are using gold immunochromatography assay(GICA) to detect influenza virusantigen from throat swab (Flu-antigen method) and enzyme-linked immunosorbentassay (ELISA) to detect specific IgM antibody (Flu-IgM method) of the influenza virusin the serum.Results:(1) In62patients,gold immunochromatography assay to detect influenzavirus antigen is positive (Flu-antigen method) in13cases, the positive rate of20.97%;enzyme-linked immunosorbent assay to detect influenza virus antibody IgM (Flu-IgMmethod) is positive in17cases, the positive rate of27.4%. Same period in parallel withthe healthy control group: Flu-IgM method is positive in1case,3.03%. Flu-antigenmethod has no positive cases.Compare Flu-antigen to Flu-IgM method,the sensitivityof Flu-antigen method is66.7%and the specificity is98.7%, P <0.01. The positiveresults of the two methods are significantly higher than the corresponding healthycontrol group, P <0.05.(2) Flu-antigen method positive results:25.0%of acuteexacerbation of chronic bronchitis, was significantly higher than the healthy controlgroup, P <0.05. Flu-IgM method positive results:25.0%of acute exacerbation of chronicbronchitis,38.5%of CAP,27.8%of AECOPD are significantly higher than the healthycontrol group, P <0.05.(3)≧65years of age,16.7%of Flu-antigen method ispositive,27.8%of Flu-IgM method is positive. Contrast≧65years of age and <65years of positive results, Flu-antigen method P>0.05; Flu-IgM method0.05<P<0.1.76.9%of Flu-antigen method positive results have underlying disease.66.7%ofFlu-IgM method positive results have underlying disease.Conclusions:(1) Influenza virus infection is associated with the underlying disease;(2) The influenza virus is an important pathogen of respiratory infection, andmany respiratory diseases are related to influenza virus infection.