The virus that causes fifth disease (parvovirus B19) has been found in the respiratory secretions (saliva, sputum, or nasal mucus) of infected people before the onset of the rash, when they still appear to "just have a cold." Fifth disease transmission probably occurs from person to person by direct contact with those secretions, such as sharing drinking cups or utensils.
Fifth disease infections can occur year-round, but they are more common during winter and spring months.
(Click Fifth Disease Transmission for more information.)
When a person becomes infected with a parvovirus, the virus begins to multiply within the body. In most cases, symptoms begin after 4 to 14 days; however, it may take 20 days for symptoms to appear. The period between becoming infected and the start of symptoms is called the fifth disease incubation period.
Common symptoms are usually mild and can include:
- "Slapped cheek" rash on the face
- Lacy, red rash on the trunk, arms, and legs.
A few days before the characteristic rash appears, some people may have early symptoms that include:
- Low-grade fever
- Body aches
(Click Fifth Disease Symptoms for more information.)
Making a DiagnosisIn order to diagnose fifth disease, the doctor will ask a number of questions about a person's symptoms and history of medical conditions. He or she will also perform a physical exam. During the physical exam, a doctor can often diagnose this condition by seeing the typical fifth disease rash.
In cases in which it is important to confirm the diagnosis of fifth disease, a blood test may be done to look for antibodies (proteins that the body makes to fight viruses) to parvovirus.
(Click Diagnosing Fifth Disease for more information.)