A Pilot Study of Influenza Viruses Isolated From Immunocompromised Children and Adolescents

The purpose of the proposed study is to gather critical information that may be useful in designing effective prevention and treatment strategies for control of seasonal influenza and an influenza pandemic. In particular, the critical questions are related to the virus' ability to adapt to efficient replication and spread in humans. Influenza is a contagious respiratory illness caused by influenza A and B viruses. Influenza infections result in about 230,000 hospitalizations and 36,000 deaths annually in the United States. Children with cancer are more likely to have serious influenza and complications than those who have no underlying medical problems. They are also more likely to have prolonged influenza illnesses and to shed influenza viruses from their noses for long periods of time (sometimes for months). Recent studies suggest that influenza viruses may also be carried and shed from the gastrointestinal tract. New types of influenza viruses emerge frequently through mutations that occur when the viruses replicate. These mutations allow the virus to escape from killing by the immune system and are, in large part, responsible for seasonal epidemics of influenza that occur in the fall or winter months. It is possible that viruses can mutate when they are carried in the respiratory or gastrointestinal tracts for long periods, potentially giving rise to viruses that spread more easily to other persons, cause more severe disease, lead to new influenza epidemics or make the viruses resistant to drugs used to treat influenza. Researchers at St. Jude Children's Research Hospital want to learn about how influenza viruses mutate in immunocompromised children. They will investigate how long children with cancer carry influenza viruses in their nose, throat and gastrointestinal tract and the characteristics of any mutations that are found in these viruses.