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Fifth Disease (Erythema Infectiosum)
What is erythema infectiosum?
Erythema infectiosum is a viral illness caused by human parvovirus B19. It is also called fifth disease, derived from the assignment of numbers to the six most common childhood rash illnesses. In the United States, the prevalence of B19 antibodies ranges from 5% to 10% in children less than 5 years old to greater than 50% in adults.
What are the symptoms of erythema infectiosum?
The manifestation of B19 infection ranges from inapparent, asymptomatic infection to a two-phase illness. Mild symptoms consisting of a low grade fever, headache, and muscle aches may develop within a week after infection. Within roughly 10 days later, the characteristic slapped cheek rash develops. The rash may spread to the extremities. In adults, arthralgias and arthritis are the most common symptoms.
Are there any complications to B19 infections?
Generally, complete recovery is the rule. People with anemia such as sickle cell anemia are at risk for developing transient aplastic crisis (TAC). The aplasia generally lasts 7 to 10 days. Rash is often not present in children with TAC. If a woman is infected in the first half of pregnancy there is a risk of fetal infection. B19 infection in pregnancy can lead to hydrops fetalis (extensive edema of the fetus) and fetal death in less than 10% of infections. Infection in an immunocompromised person can lead to severe, chronic anemia.
How is B19 spread?
The virus is believed to be spread via respiratory secretions. It also can be spread from mother to fetus. Rarely, the virus is transmitted by blood and blood products (especially clotting factor treatments).
What is the incubation period for erythema infectiosum?
The incubation period varies person to person, ranging 4 to 20 days for the development of rash or aplastic crisis.
When is an infected person contagious?
For most people with rash illness alone, they are most contagious prior to onset of rash. After the onset of the rash, these people are probably no longer communicable. People with aplastic crisis are communicable up to one week after onset. Immunocompromised people may be contagious for weeks to months after infection.
Do people with B19 infections need to be treated?
The overwhelming majority of children and adults with B19 infections do not need treatment. The illness is usually self-limited and probably produces lifelong immunity. People with anemia and immunosuppression may be treatment. For people whose B19 infection led to TAC, blood transfusion and hospitalization may be necessary. For people with immunosuppression, intravenous immunoglobulin may be needed.
Are there any measures to prevent B19 infections?
Since the virus is shed before signs and symptoms of erythema infectiosum, it is impossible to identify and exclude people from day care or school. Handwashing is recommended to reduce transmission.
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