title: Detection of human influenza virus in Yucatan, Mexico.
abstract: OBJECTIVE
  Influenza virus is the most common cause of Acute Respiratory Infections (ARI) world wide. In patients with chronic condition, infection by the influenza virus can cause complications such as pneumonia which may have fatal outcome. The aim of this work was to determine the frequency of human influenza virus in outpatients with influenza-like illness (ILI) and in those patients admitted to hospital with community acquired pneumonia (CAP) in Yucatan, Mexico (October 1998-July 1999).
  
  
  METHODS
  Throat swabs were collected from ILI and CAP patients and processed to detect respiratory viruses. All clinical samples were tested for seven respiratory viruses using a rapid indirect immunofluorescence test (IFI). Clinical samples with positive results for influenza virus by IFI were inoculated into chick embryo eggs and/or MDCK cells for viral isolation. All influenza virus isolates were typed using the WHO influenza Kit 1998-1999.
  
  
  RESULTS
  A total of 288 clinical samples were collected. Influenza virus type A was diagnosed in 29 clinical samples (10%), no other respiratory viruses were identified. Influenza virus was present with 8.9% (17 out of 189) in ILI patients, whereas with 12.12% (12 out of 99) in CAP patients. Influenza virus was detected from December to July. Six viral isolates were obtained and identified as influenza A (H3N2).
  
  
  CONCLUSIONS
  Human influenza virus is certainly a cause of ARI and pneumonia in Yucatan, Mexico. The results showed that influenza virus contributes to at least 8.9% of the ARI, and more importantly to 12% of CAP patients. Positive cases were present in a different pattern to temperate zones where the peak of incidence occurs during autumn and winter.
authors.affiliation: Laboratorio de Hematología, Centro de Investigaciones Regionales Dr. Hideyo Noguchi, Universidad Autónoma de Yucatán. talavera@tunku.uady.mx
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Ayora-Talavera
authors.forename: Renán A
authors.initials: RA
authors.lastname: Góngora-Biachi
authors.forename: Irma
authors.initials: I
authors.lastname: López-Martínez
authors.forename: William
authors.initials: W
authors.lastname: Moguel-Rodríguez
authors.forename: Humberto
authors.initials: H
authors.lastname: Pérez-Carrillo
authors.forename: Víctor
authors.initials: V
authors.lastname: Vázquez-Zapata
authors.forename: Diliana
authors.initials: D
authors.lastname: Bastarrachea-Vázquez
authors.forename: Armando
authors.initials: A
authors.lastname: Canto-Cab
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D002460:Cell Line; D002648:Child; D002675:Child, Preschool; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000821:virology; D004285:Dogs; D004847:Epithelial Cells / Q000821:virology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007223:Infant; D009980:Influenza A virus / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D007297:Inpatients; D007668:Kidney; D008297:Male; D008800:Mexico / Q000453:epidemiology; D008875:Middle Aged; D010045:Outpatients; D010614:Pharynx / Q000821:virology; D011024:Pneumonia, Viral / Q000453:epidemiology / Q000821:virology; D015995:Prevalence; D012621:Seasons; D014329:Tropical Climate; D014776:Virus Cultivation