title: Seasonality of viral respiratory infections in southeast of Brazil: the influence of temperature and air humidity.
abstract: Viruses are the major cause of lower respiratory tract infections in childhood and the main viruses involved are Human Respiratory Syncytial Virus (HRSV), Human Metapneumovirus (HMPV), Influenzavirus A and B (FLUA and FLUB), Human Parainfluenza Virus 1, 2 and 3 (HPIV1, 2 and 3) and Human Rhinovirus (HRV). The purposes of this study were to detect respiratory viruses in hospitalized children younger than six years and identify the influence of temperature and relative air humidity on the detected viruses. Samples of nasopharyngeal washes were collected from hospitalized children between May/2004 and September/2005. Methods of viral detection were RT-PCR, PCR and HRV amplicons were confirmed by hybridization. Results showed 54% (148/272) of viral positivity. HRSV was detected in 29% (79/272) of the samples; HRV in 23.1% (63/272); HPIV3 in 5.1% (14/272); HMPV in 3.3% (9/272); HPIV1 in 2.9% (8/272); FLUB in 1.4% (4/272), FLUA in 1.1% (3/272), and HPIV2 in 0.3% (1/272). The highest detection rates occurred mainly in the spring 2004 and in the autumn 2005. It was observed that viral respiratory infections tend to increase as the relative air humidity decreases, showing significant association with monthly averages of minimal temperature and minimal relative air humidity. In conclusion, viral respiratory infections vary according to temperature and relative air humidity and viral respiratory infections present major incidences it coldest and driest periods.
authors.affiliation: Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, Departamento de Biologia , Ribeirão Preto , Brasil.
authors.forename: Luiz Gustavo
authors.initials: LG
authors.lastname: Gardinassi
authors.forename: Paulo Vitor
authors.initials: PV
authors.lastname: Marques Simas
authors.forename: João Batista
authors.initials: JB
authors.lastname: Salomão
authors.forename: Edison Luiz
authors.initials: EL
authors.lastname: Durigon
authors.forename: Dirce Maria
authors.initials: DM
authors.lastname: Zanetta Trevisan
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Cordeiro
authors.forename: Mauricio Nogueira
authors.initials: MN
authors.lastname: Lacerda
authors.forename: Paula
authors.initials: P
authors.lastname: Rahal
authors.forename: Fátima Pereira
authors.initials: FP
authors.lastname: de Souz
keywords: HRSV; HRV; Relative Air Humidity; Temperature; Viral Respiratory Infections
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