Measles is a highly contagious virus that lives in the nose and throat mucus of an infected person. It can spread to others through coughing and sneezing. Also, measles virus can live for up to two hours on a surface or in an air space where the infected person coughed or sneezed. If other people breathe the contaminated air or touch the infected surface, then touch their eyes, noses, or mouths, they can become infected.
Measles is a disease of humans; measles virus is not spread by any other animal species.
Measles is so contagious that if one person has it, 90% of the people close to that person who are not immune will also become infected.