Parvovirus and Leukopenia
abstract & commenatary
Synopsis: Parvovirus B19 (erythrovirus B19) may cause leukopenia as well as anemia.
Source: Barlow GD, McKendrick MW. Parvovirus B19 causing leucopenia and neutropenia in a healthy adult. J Infect 2000;40:192-195.
Parvovirus b19 (erythrovirus b19) causes an ever increasing variety of manifestations, though infection usually is a self limiting febrile process with evanescent rash and polyarthralgia. Erythroid aplasia is the hallmark of infection. Myeloid aplasia is uncommon; there are a small number of cases with neutropenia but such cases still remain reportable. In this report from Sheffield, UK, a 27-year-old flight attendant was sick for only 12 hours when she presented with malaise, global headache, lower back pain, and intestinal distress. She had three such previous illnesses, each resolving within 48 hours. On day 2, her temperature rose to 38.7° and the WBC was 1.9 with absolute neutrophils at 830. Initial antibody to many pathogens including Toxoplasma gondii, Mycoplasma pneumoniae, Chlamydia psittaci, and parvovirus B19 were negative.
Outpatient visits at one and three weeks, respectively, after discharge revealed persistent lethargy but blood counts had returned to normal. The tip of her spleen was palpable on each visit. Convalescent serum IgM and IgG antibody to parvovirus B19 were positive by RIA and ELISA. Parvovirus DNA as determined by PCR amplification was also positive.
The report includes analysis of 11 previous cases of leukopenia in healthy adults. Ten were females and the average age was only 31. WBCs ranged from 0.5 to 2.5. Four had hemoglobin less than 10. Six had a haemophagocytic syndrome.
Comment by Joseph F. John, MD
As Barlow and McKendrick note, parvovirus infection may have atypical manifestations including ITP, aplastic anemia, peripheral neuropathy systemic vasculitis, hepatitis, and myocarditis. B19 infection can mimic lupus or Kikuchi’s disease, presenting as histiocytic necrotising lymphadenitis. This is quite a virus, and it has a stealth-like character to its invasiveness.
From the composite case reports now available for parvovirus, it seems B19 is capable of affecting any stem cell lineage. A tip off to the diagnosis of B19 infection, then, simply is an unexplained thrombocytopenia, anemia, or, as in this patient, unexplained leukopenia associated with a rash and persistent malaise.
The use in making the diagnosis, especially in these young patients, is the probability of a subtle immune deficiency that may have future effect for the individual patient. As Barlow and McKendrick emphasize as they close the paper, it is likely that leukopenia and neutropenia secondary to parvovirus B19 infection are more common than appreciated. Most cases will remain subclinical and never require a physician’s intervention.