Influenza Infection

Influenza A and B viruses cause seasonal respiratory illness. After respiratory transmission, influenza virus attaches to and enters respiratory epithelial cells, replicates, and injures those cells. The host inflammatory response contributes to the abrupt systemic symptoms that distinguish influenza from a minor upper-respiratory illness: fever or chills, headache, myalgia, malaise, and marked fatigue often accompany cough and sore throat. Antigenic drift is the gradual change in influenza surface proteins. It can reduce recognition by antibodies from prior infection or vaccination and is one reason vaccine strains are reviewed each season. Antigenic shift is an abrupt major change in influenza A that can leave much of the population with little immunity. Most people recover without hospital care, but influenza can cause viral pneumonia, secondary bacterial pneumonia, respiratory failure, sepsis, neurologic complications, or worsening of chronic cardiac or respiratory disease. Older adults and immunocompromised people may not have a prominent fever, so severity is judged from oxygenation, work of breathing, circulation, hydration, mental status, and the direction of change rather than temperature alone. The RPN performs focused assessment, applies immediate nursing measures,...