Basics
Description
Parvovirus B19 (B19) is a small, single-stranded DNA virus of the family Parvoviridae. There are three major genetic variants (1 " 3). B19 is a common infection in humans, most often associated with the childhood exanthem, erythema infectiosum, or fifth disease.
Epidemiology
- B19 infections are ubiquitous worldwide, occurring most often in school-aged children.
- Humans are the only hosts.
- Incubation period is 4 " 14 days but can be as long as 21 days.
- Modes of transmission
- Contact with respiratory secretions
- Percutaneous exposure to blood or blood products (1,011 virions/mm of serum in patients with hereditary hemolytic anemias)
- Vertical transmission from mother to fetus
Incidence
Attack rates: 15 " 60% of susceptibles (i.e., seronegative) will become infected upon exposure.
Prevalence
- Seroprevalence of B19 IgG antibodies
- >5 years old: 2 " 9%
- 5 " 18 years old: 15 " 35%
- Adults: 30 " 60%
- Elderly: 90%
General Prevention
- B19 transmission can be decreased through routine infection control 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 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, day care) is not recommended.
Pathophysiology
- Parvovirus B19 inhibits erythropoiesis by lytically infecting 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.
- Papular purpuric gloves and socks syndrome (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-Sch Άnlein purpura have also been associated with B19 infection.
Diagnosis
Diagnosis depends on recognition of typical symptoms and the results of laboratory testing.
History
- Erythema infectiosum (fifth disease)
- Characterized by an erythematous facial rash with a distinctive "slapped cheek " appearance, often accompanied by circumoral pallor
- A symmetric, macular, often lace-like rash occurs on the trunk, spreading outward to the rest of the body and extremities. The rash is often pruritic and may intensify with exposure to sunlight, heat, or exercise. It occasionally involves the palms and soles. Rarely, the rash can be papular, vesicular, or purpuric. It may last for ~7 days, but can persist >20 days.
- A brief, mild prodrome of systemic symptoms, including headache, sore throat, myalgias, and low-grade fevers, often precedes the appearance of rash by 7 " 10 days.
- The child is usually well-appearing and remains active and playful.
- Aplastic crisis
- Prodromal symptoms in B19-infected children with sickle cell disease or other hereditary hemolytic anemias are nonspecific and consist of fever, malaise, and headache. Rash is usually absent.
- Symptoms are usually self-limited, lasting 7 " 10 days.
- Severe anemia, CHF, stroke, and acute splenic sequestration have also been associated.
- Chronic anemia/pure red cell aplasia
- In immunocompromised patients, B19 infection may persist for months, leading to chronic anemia with B19 viremia.
- Low-grade fever and neutropenia may accompany anemia.
Physical Exam
Fifth disease
- An erythematous facial rash with a "slapped cheek " appearance, often associated with circumoral pallor
- Truncal, macular, lacy-appearing rash spreading to the arms, buttocks, and thighs
- Often pruritic and may become more intense with exercise or heat exposure
- Occasionally can be found on the palms and soles, and rarely can be papular, vesicular, or purpuric
Diagnostic Tests & Interpretation
Lab
- There is no practical in vitro system for isolation or culture of the virus.
- Antibodies
- Detection of parvovirus B19-specific IgM or IgG antibodies as determined by EIA or radioimmunoassay
- The presence of B19-specific IgM antibodies is diagnostic in patients with symptoms of erythema infectiosum or aplastic crisis. IgM- and IgG-specific antibodies are detected in 90% of such patients by 3 " 7 days of illness.
- B19-specific IgG antibodies persist for life, whereas specific IgM antibodies begin to decrease 30 " 60 days after onset of illness.
- Polymerase chain reaction (PCR) techniques
- B19 DNA can be detected by PCR in serum for up to 9 months following the initial viremic phase. B19 DNA has also been shown to persist in solid tissues following primary infection, even in healthy individuals. Thus, identification of B19 DNA does not necessarily signify acute infection.
- Immunocompromised patients with chronic marrow suppression may be unable to produce B19-specific IgG or IgM antibodies. In such cases, PCR for B19 viral DNA is the diagnostic method of choice.
- PCR may also be used to detect virus in the fetus.
- Hematocrit and reticulocyte count in patients with aplastic crisis
- Laboratory studies reveal reticulocytopenia, usually with counts of <1%. During the illness, the patient 's hematocrit may fall as low as 15%.
Differential Diagnosis
B19 infection should be considered in all patients with arthritis or viral exanthems with a consistent history and exam.
Treatment
General Measures
- There is no specific antiviral therapy for B19 infection.
- Most patients require supportive care only. However, transfusions may be required for treatment of severe anemia in patients with aplastic crisis.
- IV immunoglobulin (IVIG) therapy has been given with some success to patients with chronic marrow suppression secondary to B19 infection.
- The mainstay of treatment for an infected fetus is delivery, but intrauterine transfusions may be lifesaving.
Ongoing Care
Follow-up Recommendations
Expected course of illness
- The rash of erythema infectiosum in a child or adult may last up to 20 days. It may, at times, fade and/or intensify, depending on sunlight exposure, exercise, or body surface temperature changes (e.g., bathing).
- During aplastic crisis secondary to B19, the reticulocyte count usually remains low (often <1%) for ~8 days before spontaneous recovery.
Prognosis
- The prognosis is quite good for all manifestations of B19 infections.
- Most patients recover spontaneously and require only supportive care.
Complications
- Parvovirus B19 during pregnancy
- 30 " 50% of pregnant women are susceptible to B19 infection.
- Fetal loss, intrauterine growth retardation, or hydrops fetalis may result from maternal infection with B19 during pregnancy. Fetal death occurs in 2 " 6% of cases.
- B19 has not been proven to cause congenital anomalies.
- The greatest risk for B19 infection affecting the fetus exists in the first 20 weeks of gestation.
- The risk of fetal death after exposure, if antibody status is unknown, is <1.5%.
- There is no indication for elective abortion in cases of maternal infection.
- Arthritis/arthropathy
- Although most cases of polyarthritis resolve within 2 weeks, persistent symptoms for months to even years (rarely) have been reported.
Additional Reading
- Douvoyiannis M, Litman N, Goldman DL. Neurologic manifestations associated with parvovirus B19 infection. Clin Infect Dis. 2009;48(12):1713 " 1723. [View Abstract]
- Molina KM, Garcia X, Denfield SW, et al. Parvovirus B19 myocarditis causes significant morbidity and mortality in children. Pediatr Cardiol. 2013;34(2):390 " 397. [View Abstract]
- Lamont RF, Sobel JD, Vaisbuch E, et al. Parvovirus B19 infection in human pregnancy. BJOG. 2011;118(2):175 " 186. [View Abstract]
- Smith-Whitley K, Zhao H, Hodinka RL, et al. Epidemiology of human parvovirus B19 in children with sickle cell disease. Blood. 2004;103(2):422 " 427. [View Abstract]
- Young NS, Brown KE. Parvovirus B19. N Engl J Med. 2004;350(6):586 " 597. [View Abstract]
Codes
ICD09
- 057.0 Erythema infectiosum (fifth disease)
ICD10
- B08.3 Erythema infectiosum [fifth disease]
SNOMED
- 34730008 erythema infectiosum (disorder)
FAQ
- Q: When may children with B19 infection return to school?
- A: Children are contagious only during the prodromal phase of illness, which is often unrecognized. Once the rash appears, they are no longer infectious and may return to school or day care.
- Q: What can be done to reduce risk of fetal infection?
- A: Because B19 infections during pregnancy may result in fetal death, and B19 infections often occur in community outbreaks, fetal risks following maternal exposure to persons with recognized B19 infection are a frequent concern. Risk to the fetus appears to be greatest if the infection occurs prior to the 20th week of gestation. Among pregnant women of unknown antibody status, the risk of fetal death after exposure to B19 is estimated to be <1.5%. Routine exclusion of pregnant women from the workplace when B19 infection is suspected is not recommended. However, pregnant teachers who are at risk for infection may consider a leave of absence during community outbreaks of B19.