About 50 percent of all adults have been infected sometime during childhood or adolescence with parvovirus B19, a virus that only infects humans. About 25 percent of people infected with this virus never develop any symptoms. Another 50 percent will only have flu-like symptoms, such as fever, excessive tiredness, headache, and muscle pain. The remaining 25 percent will have the classic symptoms of infection, including:
- Joint pain
- Joint swelling.
Many of the illnesses that parvovirus B19 can cause have been categorized into syndromes, such as:
- Fifth disease (erythema infectiosum or slapped cheek syndrome)
- Arthropathy (a condition that affects the joints)
- Chronic anemia in people with a compromised immune system.
Many of these conditions occur because parvovirus B19 causes problems with cells in the bone marrow.
(Click Parvovirus B19 to learn more about the effects of this virus.)