Watch a Johns Hopkins expert answer frequently asked questions about measles, including the seriousness of the disease (0:15), why vaccination is important (1:01), whether one dose of the vaccination is enough (2:27), and if measles is worse for adults (3:42). Measles, also known as rubeola, is a viral illness that is very contagious. Symptoms include a distinct rash, fever, runny nose, cough, swollen lymph nodes and headache. The measles virus can be dangerous for children under 5 and can cause serious conditions in adults if not vaccinated properly. Learn more on what you need to know at http://ow.ly/JKqx1.