Influenza is an acute infectious disease of the respiratory tract caused by the influenza virus which occurs in three types: A, B and C. The most significant threat to humans arises from the influenza A viruses.
Gripp on äge hingamiselundite nakkushaigus, mida põhjustavad kolme tüüpi gripiviirused – A, B ja C. Inimesele kõige ohtlikumad on A-tüüpi gripiviirused.