Clinical manifestations of human parvovirus B19 infection can vary widely and may be atypical in solid organ transplant (SOT) recipients. However, disease is apparent when there is destruction of erythrocyte progenitor cells leading to severe acute or chronic anemia with lack of an appropriate reticulocyte response in the setting of active parvovirus B19 infection. Serology may not reliably establish the diagnosis. High-level viremia is more likely to be associated with symptomatic disease. Conversely, ongoing DNAemia after infection may not be clinically significant, if detected at low levels. Despite lack of robust data, intravenous immunoglobulin (IVIG) is frequently used for the treatment of SOT recipients with symptomatic parvovirus B19 infection. Although the optimal dosage and duration of IVIG is not known, most patients receive a total of 2 g/kg over a period of 2-5 days. A daily dose of 1 g/kg or more seems to be associated with higher incidence of toxicity. Application of standard and droplet isolation precautions remains the cornerstone for preventing human parvovirus B19 transmission. Additional research is needed to assess the efficacy of current and novel therapies and to develop a safe and effective parvovirus B19 vaccine.

Until recently, B19 virus was considered to be the only human pathogen of the genus erythrovirus. However, other non-B19 virus strains, such as V9, have now been isolated and are thought to cause infections clinically and serologically indistinguishable from those caused by B19 virus. Whereas B19 virus related isolates have a low genetic diversity of only 1-2%, nucleotide disparity of up to 12% was found for the new isolates, suggesting that non-B19 virus isolates may not be detectable using B19 virus specific PCR methods. To overcome this problem, we designed consensus primers and probes to enable the simultaneous detection of both B19 and non-B19 virus and subsequent discrimination of the two lineages by melting temperature (T(m)) analysis. A total of 196 clinical specimens, from 185 patients with a history of or an anamnesis resembling B19 virus infection, were analyzed using the consensus PCR test. Erythrovirus DNA was detected in 37 of these samples and was found to be B19 virus specific in each case, confirming previous results using B19 virus specific PCR. Although no non-B19 virus DNA was detected in any of the clinical samples tested in this study, more extensive studies are warranted. The routine use of erythrovirus consensus PCR in the diagnosis of B19 virus infection should provide valuable information on the epidemiology and clinical role of non-B19 virus isolates; its use in screening would increase the safety of blood products.

Human parvovirus B19 is the cause of a common childhood disease that usually has a mild and self-limited course. Complete viral replication and subsequent cell lysis are limited to early erythroid precursor cells expressing the globoside receptor. Individuals with shortened red blood cell half-lives and immunocompromised or immunosuppressed patients, as well as pregnant women and developing fetuses, are at risk for severe anemia and/or persistent infection from human parvovirus B19. Selection of the diagnostic test(s) to use to detect parvovirus B19 is patient dependent. Serological testing is most appropriate in immunocompetent individuals, including children and pregnant women, who have symptoms consistent with parvovirus B19 infection or a history of recent exposure. Conversely, a molecular amplification assay should be chosen to detect parvovirus B19 DNA in individuals lacking an adequate antibody-mediated immune response. In summary, it is critical that clinicians are educated about the most appropriate diagnostic test to detect parvovirus B19 infection in their patients because selecting an inappropriate or inaccurate test for parvovirus B19 can lead to misinformation and/or misdiagnosis.