In a word, yes, fifth disease is contagious. Usually, a person infected with the parvovirus is contagious before the rash itself appears. This makes fifth disease different from the other rashes it's often confused with, since those conditions are infectious while the rash is present. Since the earlier symptoms of parvovirus are similar to those of a common cold, it's often difficult to prevent the infected person from spreading it to others [source: Center for Disease Control].
The parvovirus typically spreads when an infected person exhales airborne droplets containing the virus, then another person comes into contact with the droplets [source: Wisconsin Department of Health Services]. The good news about that is it's possible to prevent spreading infection by practicing good hygiene. When coming down with symptoms of the disease, be sure to frequently wash your hands and throw away used tissues right after use. This may seem like simple advice, but it is an easy way to prevent the spread of disease since your hands come into contact with many shared objects, particularly in public places [source: Mayo Clinic: Parvovirus].
Washing your hands might be easy, but if you've ever tried to get a kid to do it, you won't be surprised to learn how and where fifth disease usually spreads. While you're at it, check out the myths surrounding the rash and animals.