Determining susceptibility to- and diagnosis of parvovirus infection in a pregnant woman exposed to a confirmed/suspected parvovirus infected individual, or presenting with signs or symptoms of parvovirus infection.
Indications for Testing
Pregnant woman exposed to a confirmed/suspected parvovirus infected individual to determine if they are susceptible to infection (nonimmune).
Pregnant woman who develops signs and symptoms of parvovirus infection.
Parvovirus screening should not be ordered as part of routine prenatal serology.
Parvovirus B19 is the causative agent of fifth disease (erythema infectiosum, slapped cheek syndrome), which usually produces a mild illness characterized by an intensive erythematous maculopapular facial rash in children. Parvovirus B19 has been shown to be the causative agent of a number of clinical conditions such as rash, arthralgia and fetal damage. Parvovirus B19 infection in adults, especially woman, may cause acute arthritis which can persist for some time. Infection can lead to life threatening anemia in immunocompromised patients and individuals with underlying haemolytic disorders such as sickle cell disease.
Seronegative woman are susceptible to ParvovirusB19 infection. The majority of pregnancies during which Parvovirus B19 infection occurs result in delivery of a healthy fetus at term. However, infection during pregnancy presents the risk of transmission to the fetus which may result in hydrops fetalis or intraurterine death due to infection of red blood cell precursors leading to fetal anemia whereby the hemoglobin levels fall to < 2g/dl. The rate of fetal death following maternal infection ranges between 1% and 9%.
Most outbreaks of parvovirus infection are acquired by direct contact with respiratory secretions and occur in the spring of the year. Close contact between individuals is responsible for infection in schools, daycare centers, and hospitals. Of note, symptoms associated with Parvovirus B19 infection only become apparent after the viremic (contagious) phase.
Both IgG and IgM may be present at or soon after onset of illness and reach peak titers within 30 days. Because IgG antibody may persist for years, diagnosis of acute infection is made by the detection of IgM antibodies.
The prevalence of parvovirus B19 IgG antibodies increases with age. The age-specific prevalence of antibodies to parvovirus is 2-9% of children under 5 years, 15-35% in children 5 to 18 years of age, and 30-60% in adults (19 years or older).
Parvovirus B19 infection is common in childhood, and by age 15 approximately 50% of children have detectable immunoglobulin G (IgG) against Parvovirus B19. Infection also occurs in adult life, and more than 80% of elderly people have detectable antibody. Women of child-bearing age in the United States and Europe have an annual seroconversion rate of approximately 1%. Studies in different countries (France, Germany, Japan, the United Kingdom, and the United States) show similar patterns, with a slightly higher prevalence in children from countries such as Africa and Brazil. Some isolated tribal populations have a much lower prevalence: 2% on Rodriquez Island, Africa, and 4% to 10% among the tribes around Belem, Brazil.
At least four different parvoviruses are known to infect humans. Parvovirus B19 (B19V) is the best characterized, and is classified as a member of the Erythrovirus genus, of which it is the type species. The other human viruses are the human adeno-associated viruses (AAVs, or dependoviruses), human bocavirus (HboV), and human parvovirus 3. The last two viruses have not officially been classified yet, but HboV is clearly a member of the Bocavirus genus, whereas human parvovirus 4 is markedly different from all other known viruses, and will probably become part of a new genus.
Parvoviridae are among the smallest known DNA-containing viruses that infect mammalian cells. The virions are nonenveloped particles about 22nm in diameter with icosahedral symmetry. The Parvoviridae are divided into two subfamilies Parvovirinae and Densovirinae, on the basis of their ability to infect vertebrate or invertebrate cells, respectively. The Parvovirinae are futher subdivided into five genera on the basis of their transcription map, their ability to replicate efficiently either autonomously or with helper virus, and their sequence homology. The five genera are: Parvovirus, Dependovirus, Erythrovirus, Bocavirus, and Amdovirus.
Reactive: A reactive result does not differentiate active/past infection. Reactive result in the absence of IgM indicates immunity.
Non-reactive: A non-reactive result does not exclude early active infection. If clinically indicated submit a follow-up specimen. No evidence of immunity.
Indeterminate: Specimen produced results near the cut-off (indeterminate), please submit a follow up specimen 2 – 4 weeks to resolve. Insufficient evidence of immunity.
Society of Obstetricians and Gynecologists of Canada. 2002. Parvovirus B19 infection in pregnancy. JOGC. 119:1-8.
Brown, K. E. 2010. Human Parvoviruses, Including Parvovirus B19 and Human Bocavirus, p. 2087-2095. In Mandell, D., Bennett, J. E., and Dolin, R. Principles and practice of infectious diseases, 7th ed., vol. 2. Churchill Livingstone, Elsevier, Philadelphia, PA.
Jordan, J. A. 2007. Human Parvoviruses, p. 1622-1623. In Murray, P. R., Baron, E. J., Jorgensen, J. H., Landry, M. L., and Pfaller, M. A. Manual of Clinical Microbiology, 9th ed., vol. 2. ASM Press, American Society for Microbiology, Washington, DC.
Biotrin. 2008. Parvovirus B19 IgG Enzyme Immunoassay Package Insert. Biotrin International Ltd. Dublin, Ireland.