The patient described had previously been healthy, and his two sons were found to have HS within one month. Combining his medical history and family history, it is highly suspected that HS is complicated. Finally, genetic testing was performed to confirm the diagnosis. The patient had positive IgM serology for B19 V, EBV and CMV. EBV viral capsid antigen IgG was positive suggesting previous EBV exposure. Thus, it can be concluded that the patient had B19 V infection which resulted in acute aplastic anemia following infection with EBV and CMV. His condition finally improved after anti-infection and anti-virus treatment, in addition to blood transfusion. His hemoglobin level increased to 118 g/L on his last visit.
Human parvovirus B19 is a small, single-stranded DNA virus and was the first human virus identified to be a member of the parvovirus genus. The virus displays remarkable tropism for human erythroid progenitor cells. In immunocompromised hosts unable to neutralize the antibody, B19 V replicates in erythrocyte precursors efficiently and preferentially, and this infection may persist and lead to pure red cell anemia and other comorbidities. It has been estimated that the peak incidence of infection occurs in children between the ages of 6 and 14 years. EBV infection also seems to share the same mechanism as B19 V in inducing bone marrow aplasia, but at present the clinical effect of an infection sustained by both viruses is unknown and there are no reports to suggest that CMV is associated with aplastic crisis or HS. Humoral immunity is the main defense in B19 V infection. Individuals infected with B19 V can produce specific antibodies, initially IgM and then IgG, and IgG can persist lifelong and protect against re-infection. ELISA is the most widely used diagnostic technique. And the earliest and most sensitive diagnostic method available is PCR, which can identify B19 V DNA in bone marrow aspirates or blood samples. The combined treatment of immunoglobulin infusion and symptomatic treatments including blood transfusion is effective in neutralizing B19 V and improving anemia, especially pure red cell aplastic anemia as reported previously. In this case, infection with B19 V was confirmed both by the detection of B19 V DNA using PCR and the presence of B19 V IgM by serology and the patient improved following antiviral treatment and erythrocyte infusion.
There have been several case reports of B19 V infection in patients with HS, but this is not frequently described and most of these cases were children or adolescents[9–11]. Yujin Kobayashi reviewed this infection in a series of adult patients. In his study, a total of 19 reports were included involving 22 cases between 1984 and 2010, only 6 patients were male, and all patients were young aged between 18 and 43 years. The only case of B19 V, EBV and CMV co-infection documented to date describes twins with previously unidentified HS. To our knowledge, this is the first report to describe a case with B19 V, EBV and CMV co-infection diagnosed in an adult male patient with HS in China. The infection only produced transient pure red cell aplastic anemia and the reason why there was no additive effect of the three viruses on the patient’s aplastic crisis is still unclear. We report this case in order to provide new data on the clinical diagnosis and treatment of this rare disease.