Rubella is a mild febrile rash illness caused by rubella virus. It is transmitted from person to person via droplets (the virus is present in throat secretions). It affects mainly, but not only, children and when pregnant women are infected, it may result in malformation of the foetus. Humans are the only reservoir of infection.
Measles is an acute illness caused by morbillivirus. The disease is transmitted via airborne respiratory droplets, or by direct contact with nasal and throat secretions of infected individuals.
Influenza is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. It can cause mild to severe illness, and at times can lead to death. The best way to prevent flu is by getting a flu vaccine each year.