title: [Endemic corridors: a useful tool for the epidemiological surveillance of influenza].
abstract: Epidemiological surveillance provides updated information about health problems which allows for the establishment of health policy guidelines. The methods for detecting the epidemic frequency of disease require the systematic collection of data on the occurrence of specific diseases. Influenza has cyclic seasonal peaks and its endemic baseline rates are useful for identifying outbreaks: the comparison between baseline and current data supplies epidemiological evidence related to an ongoing outbreak. The upper and lower incidence curves were traced for the data referring to IA detection in the nasopharyngeal aspirates from children hospitalized for acute lower respiratory tract infection from 1996 to 2002. The arithmetic mean and the 95% confidence interval for upper and lower limits of weekly incidence were calculated. The highest incidence was observed between weeks 25 and 32. When analyzing the prepared endemic corridor, it was observed that the highest detection in 2003 occurred between weeks 19 and 25, whereas two peaks occurred in 2004, the first starting at week 20, at a lower level than the normal epidemic peak, and the second at week 26.
authors.affiliation: Hospital de Niños Pedro de Elizalde, Av. Montes de Oca 40 (C1270AAN) Ciudad Autónoma de Buenos Aires, Argentina. mjrial@fibertel.com.ar
authors.forename: M J
authors.initials: MJ
authors.lastname: Rial
authors.forename: N
authors.initials: N
authors.lastname: Alarcón
authors.forename: C
authors.initials: C
authors.lastname: Ferrario
authors.forename: M
authors.initials: M
authors.lastname: Szefner
authors.forename: G
authors.initials: G
authors.lastname: Califano
mesh_terms: D001118:Argentina / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D011159:Population Surveillance / Q000379:methods*; D012141:Respiratory Tract Infections / Q000821:virology*; D012621:Seasons