Respiratory viral threatsHayden, Frederick GCurrent Opinion in Infectious Diseases: April 2006 - Volume 19 - Issue 2 - p 169–178 doi: 10.1097/01.qco.0000216628.51563.b1 Respiratory infections Abstract Author Information Purpose of review To assess new information from peer-reviewed publications in 2005 regarding emerging respiratory viral threats. Recent findings The expanding epizootic of avian A/H5N1 influenza and increasing number of human cases heighten concern regarding the threat of pandemic influenza. Studies of the 1918 pandemic virus have shown the potential for direct interspecies transmission from an avian host. In the absence of an effective vaccine, antiviral agents could provide an important response measure. Inadequate supplies and potential antiviral resistance are limiting factors. Seasonal influenza heavily affects infants and young children, who also serve to foster transmission at the community level, findings that indicate the need for broader immunization strategies in pediatric populations. Like avian influenza, the severe acute respiratory syndrome coronavirus was a zoonotic infection, perhaps derived from related coronaviruses in bats. Molecular diagnostic techniques have led to the recent identification of several new coronaviruses and a respiratory parvovirus. It has also helped to define the impact of previously described ones such as human metapneumovirus and rhinoviruses, which account for the majority of asthma exacerbations and frequent lower respiratory tract illnesses. Summary Progress has been made in development of possible specific interventions for influenza and possibly severe acute respiratory syndrome coronavirus, but effective antivirals and vaccines for most other respiratory viruses are currently lacking. University of Virginia School of Medicine, Charlottesville, Virginia, USA Correspondence to Frederick G. Hayden, MD, University of Virginia School of Medicine, Department of Internal Medicine, Box 800473, Charlottesville, VA 22908, USA Tel: +434 924 5059; fax: +434 924 9065; e-mail: firstname.lastname@example.org © 2006 Lippincott Williams & Wilkins, Inc.