Acute lower respiratory tract infections (ALRTI) such as pneumonia and bronchiolitis are major causes of mortality and morbidity in children under 5 years of age. The main microbial agents responsible for ALRTI are either bacterial agents ( Streptococcus pneumoniae, Haemophilus influenzae type b, Mycoplasma pneumoniae ) or viruses (respiratory syncytial virus (RSV, also known as human orthopneumovirus), Myxovirus influenzae, Myxovirus parainfluenzae, adenovirus) [1]. More recently, other viruses (rhinovirus, metapneumovirus, coronavirus, bocavirus) have been implicated in ALRTI; their identification has been facilitated by new molecular biology techniques such as real-time PCR. To our knowledge, these emerging viruses have never been the subject of epidemiologic studies in our country.