Influenza. Even though influenza viruses usually cause URIs in adults, they are increasingly being recognized as an impor- tant cause of LRIs in children and perhaps the second most important cause after RSVs of hospitalization of children with an ARI (Neuzil and others 2002).Although influenza is consid- ered infrequent in developing countries, its epidemiology remains to be investigated thoroughly. The potential burden of influenza as a cause of death in children is unknown. Influenza virus type A may cause seasonal outbreaks, and type B may cause sporadic infection. Recently, avian influenza virus has caused infection, disease, and death in small numbers of indi- viduals, including children, in a few Asian countries
