The purpose of the study is to asses the various pathogens of bronchiolitis in children and its' clinical manifestations. Prospective study in 3 Medical centers in Northern Israel. Included will be about 200 infants and children < 2 years hospitalized with bronchiolitis. From each child sputum specimen will be obtained and processed for HUMP - PCR, Pertussis - PCR, RSV - ELISA, DFA, PCR, Influenza A, B, Parainfluenza 1,2,3 - DFA, PCR, Adenovirus - DFA. Epidemiological data will be obtained for every child by structured questioner. Clinical data will be daily obtained by scoring system.
Sputum specimens will be obtained from children < 2 years of age and processed by different mode for the HMPV, RSV, Pertussis, Influenza A, B, Parainfluenza 1,2,3, Adenovirus. Clinical and epidemiological data will also be obtained.