Parvovirus B19 (Erythema Infectiosum, Fifth Disease)
Parvovirus B19 (B19) is a small, single-stranded DNA virus of the family Parvoviridae. There are three major genetic variants (1 to 3). B19 is a common infection in humans, most often associated with the childhood exanthem, erythema infectiosum, also known as fifth disease.
- B19 infections are ubiquitous worldwide, occurring most often in school-aged children.
- Humans are the only hosts.
- Incubation period is 4 to 14 days (up to 21 days).
- Attack rates: 15–60% of susceptibles (i.e., seronegative) will become infected upon exposure.
- Modes of transmission
- Contact with respiratory secretions
- Percutaneous exposure to blood or blood products (1011 virions/mL of serum in patients with hereditary hemolytic anemias)
- Vertical transmission from mother to fetus
Seroprevalence of B19 IgG antibodies
- >5 years old: 2–9%
- 5 to 18 years old: 15–35%
- Adults: 50%
- Elderly: 90%
- B19 transmission can be decreased through routine infection prevention practices, including hand hygiene and appropriate disposal of contaminated facial tissues.
- For hospitalized children with suspected aplastic crisis, immunocompromised patients with chronic infection and anemia, and patients with papular purpuric gloves and socks syndrome (PPGSS) secondary to B19, droplet precautions in addition to standard precautions are recommended.
- No additional preventive measures are needed for normal hosts with rash.
- Due to the potential risks to the fetus from B19 infections, pregnant health care workers should adhere to strict infection control procedures and avoid contact with immunocompromised hosts with B19 infection or those with aplastic crisis.
- Due to high prevalence of B19 in the community, routine exclusion of pregnant women from the workplace where B19 infections are suspected (e.g., schools, child care) is not recommended.
- Parvovirus B19 inhibits erythropoiesis by lytically infecting red blood cell (RBC) precursors in the bone marrow.
- It is associated with a number of clinical manifestations, ranging from benign to severe.
Commonly Associated Conditions
- Erythema infectiosum, or fifth disease, is the most common form of infection caused by B19 and occurs in up to 35% of school-aged children.
- Asymptomatic infection may occur in ~20% of children and adults.
- Transient aplastic crisis secondary to B19 infection may cause severe anemia in patients with hereditary hemolytic anemias or any condition that shortens the RBC lifespan, such as sickle cell disease or spherocytosis.
- Polyarthropathy syndrome (symmetric joint pain and swelling, typically of the hands, knees, and feet) is seen in up to 80% of adults, especially women. Arthralgias and arthritis occur infrequently in children. When present, arthritis in children most often involves the knees.
- Hydrops fetalis may develop after maternal B19 infection with intrauterine involvement (typically within the first 20 weeks of pregnancy).
- Chronic anemia/pure red cell aplasia due to persistent B19 infection has been reported in immunocompromised patients.
- PPGSS consists of painful and pruritic papules, petechiae, and purpura localized to the hands and feet and is often associated with fever.
- B19 is one of the most common viruses identified in cases of myocarditis, although its role in pathogenesis is unclear.
- Reports of neurologic manifestations (including meningitis, encephalitis, and peripheral neuropathy), hemophagocytic syndrome, hepatitis, and Henoch-Schönlein purpura have also been associated with B19 infection, although the precise role of the virus in these conditions is unclear.
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