May I know how long fake measles last and how does it spread?

The fever of roseola lasts from 3 to 7 days, followed by a rash lasting from hours to a few days. My pd told me during the fever stage is highly contagious, only when it break into rash, then its not U can read more on http://m.kidshealth.org/en/parents/roseola.html?WT.ac=