The first four are scarlet fever, measles, rubella or German measles, and roseola. Next came Erythema infectiosum commonly known as fifth disease or 'slapped-cheek' because of the fiery red rash that erupts on the cheeks. Fifth disease is caused by parvovirus B19. It's a common infection, and by age 15 about 50 percent of children have had it. Infection also occurs later in life so that by old age over 90 percent of people are immune.
Fifth disease can be mild or serious depending on one's health and immune status.
In healthy children, infection is usually mild and brief, often causing no symptoms at all. The rash can wax and wane over a few weeks time and may reappear after exercise. In adults, especially women, about half of those infected experience joint pain and stiffness as with arthritis. Outbreaks of fifth disease are more common in late winter, spring and early summer. The virus lives in respiratory secretions in the nose and throat and is spread by close contact.