title: Genetic and clinical assessment of 2009 pandemic influenza in southern China.
abstract: BACKGROUND
  South China has a proven role in the global epidemiology of previous influenza outbreaks due to its dual seasonal pattern. We present the virologic, genetic and clinical characterization of pandemic H1N1 influenza infection (pH1N1) in Shantou and Nanchang, cities in southern China, during the second wave of the 2009-2010 pandemic.
  
  
  METHODS
  Nasopharyngeal swabs were collected from 165 individuals with influenza-like illness (ILI) who presented to the hospitals in Shantou and Nanchang. Laboratory diagnosis and characterization was performed by real-time PCR, virus isolation in embryonated chicken eggs, and sequencing.
  
  
  RESULTS
  pH1N1 activity was sustained in three different temporal patterns throughout the study period. The overall positivity rate of pH1N1 was 50% with major distribution among young adults between the ages of 13 and 30 years. High fever, cough, expectoration, chest pain, myalgia, nasal discharge and efficient viral replication were observed as major clinical markers whereas a substantial number of afebrile cases (17%) was also observed. Rate of hospitalization and disease severity (39%) and recovery (100%) were also high within the region. Furthermore, severe complications were likely to develop in young adults upon pH1N1 infection. Genetic characterization of the HA and NA genes of pH1N1 strains exhibited homogenous spread of pH1N1 strains with 99% identity with prototypic strains; however, minor unique mutations were also observed in the HA gene.
  
  
  CONCLUSIONS
  The study illustrates the detailed characteristics of 2009 influenza pandemic in southern parts of China that might help to strategize preparedness for future pandemics and subsequent influenza seasons.
authors: Division of Immunology, International Institute of Infection and Immunity, Shantou University Medical College, 22 Xinling Road, Shantou, Guangdong 515041, China. afarooqui@jidc.org
authors: Amber
authors: A
authors: Farooqui
authors: Yanchang
authors: Y
authors: Lei
authors: Pusheng
authors: P
authors: Wang
authors: Jianyun
authors: J
authors: Huang
authors: Jie
authors: J
authors: Lin
authors: Guishuang
authors: G
authors: Li
authors: Alberto J
authors: AJ
authors: Leon
authors: Zhen
authors: Z
authors: Zhao
authors: David J
authors: DJ
authors: Kelvin
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000473:pathology / Q000821:virology*; D008297:Male; D008969:Molecular Sequence Data; D009305:Nasopharynx / Q000821:virology; D009439:Neuraminidase / Q000235:genetics; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D012720:Severity of Illness Index; D014764:Viral Proteins / Q000235:genetics; D014776:Virus Cultivation; D055815:Young Adult
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D012367:RNA, Viral; D014764:Viral Proteins; C487630:NA protein, influenza A virus; D009439:Neuraminidase