An infection that causes a rash and inflammation of the joints
Fifth disease, also known as erythema infectiosum or slapped cheek disease, is caused by a strain of parvovirus (strain B19). It mainly affects children, in whom it typically causes a mild illness, with a fever that is often unnoticed. It is rare in adults but may cause severe joint pain. Parvovirus is usually transmitted in airborne droplets from the coughs and sneezes of infected individuals but it may occasionally be transmitted through a blood transfusion or from mother to fetus. Infection causes a brief halt in red blood cell production, so can have serious effects in people with anaemia.
Many children do not develop symptoms; in others they may appear within 7–18 days of infection:
Bright red rash on the cheeks that may spread to the trunk and limbs.
In rare cases, mild inflammation of the joints (see Arthritis).
Adults are likely to develop more severe symptoms that may include:
Rash on the palms and soles.
Severe inflammation and pain in the joints of the knees, wrists, and hands.
Some people develop a form of arthritis that can last for up to 2 years.
In people with reduced immunity, the infection may become long-term and can cause anaemia. Many pregnant women are immune to the virus. However, for women who are not immune, contracting the infection during the first 20 weeks of pregnancy increases the risk of miscarriage and of the baby developing hydrops fetalis, a serious condition in which there is anaemia, heart failure, and tissue swelling.
If the parvovirus infection cannot be diagnosed from symptoms a blood test may detect antibodies against the virus. One attack of parvovirus infection provides lifelong immunity.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.