Fifth disease, also known as "Erythema Infectiosum" is usually a mild illness caused by a virus. It usually occurs in cluster or outbreaks in late winter or early spring.

Most students can remain in school if there is not fever and they feel well. They are no longer contagious by the time the rash appears. It can be more serious for the immuno-suppressed person and women in their first half of pregnancy. It is highly recommended that any pregnant woman who has been exposed to Fifth's Disease contact their physician. Up to 10% of women who contact this illness during the first half of their pregnancy may miscarry or have a still-born child. Immuno-suppressed students/adults should also contact their physician. About 50% of adults are immune to this disease so your physician may want to do testing to see if you have the anti-body.

The illness is characterized first by a headache, body ache, sore throat, low-grade fever and chills -- all mimicking the signs and symptoms of the common cold. These symptoms usually last a few days and then no symptoms occur for about a week. Suddenly, a bright red rash appears on the cheeks giving a 'slapped-face' appearance and sometimes a 'lacy' rash will appear on the arms and legs. The rash lasts for about a week and then fades in and out. The incubation period is 4-20 days. Adults are less likely to have a rash but more likely to develop joint pain.

The best prevention is frequent hand washing; disposal of used facial tissues; covering coughs; and covering sneezes because the disease spreads by respiratory droplets.

http://kidshealth.org/parent/infections/bacterial_viral/fifth.html