Severe aplastic anaemia after parvovirus infection in the absence of underlying haemolytic anaemia

[Pure red cell aplasia: Diagnosis, classification and treatment]

Pure red cell aplasia (PRCA) is a rare anemia characterised by profound reticulocytopenia caused by a marked reduction in bone marrow erythroblasts, without abnormalities in other blood lineages. Blackfan-Diamond anemia is an inherited ribosomopathy responsible for a hereditary form of PRCA. Acquired PRCA are separated in primary and secondary forms, including Parvovirus B19 infection, thymoma, lymphoproliferative disorders, autoimmune diseases (lupus) and drug-induced PRCA. The pathophysiology of PRCA is not fully understood and involves both humoral and T lymphocyte autoreactive cells. In Parvovirus B19-related PRCA, treatment is based on polyvalent immunoglobulins. Thymectomy for thymoma is mandatory but results in prolonged remission in a limited number of cases. The therapeutic strategy is based on expert opinion: corticosteroids in monotherapy provide few sustained responses. The choice of an additional immunosuppressant drug is guided by the presence of an underlying disease. In most cases, cyclosporine A is the first choice providing the best response rate but requires a concentration monitoring (150 to 250 ng/mL). The second choice is cyclophosphamide in large granular lymphocyte leukaemia. Sirolimus (mTOR inhibitor) seems to be a promising option especially in refractory cases. Transfusion independence is the main objective. If the patient receives numerous red blood cell transfusions (> 20 packs), iron overload assessment is crucial to initiate an iron chelation. A retrospective and prospective national cohort (EPIC-F) has been set up and is now available to include each case of PRCA to improve the knowledge of this disease and to optimize the therapeutic strategy.

Aplastic anemia induced by human parvovirus B19 infection in an immunocompetent adult male without prior hematological disorders: A case report

Introduction and importance

Parvovirus B19 (B19V) is a human pathogenic virus of clinical relevance. Human parvovirus B19 infection can be asymptomatic or frequently associated with erythema infectiosum, or joint symptoms in healthy adults. Aplastic anemia as a complication of human parvovirus infection is rare in healthy adults without prior hematological disorders.

Case presentation

We report a case of severe aplastic anemia in a 22-years-old immunocompetent adult male without any hematological dysfunction who presented with periumbilical pain, loose watery stools, and fever with chills and rigor. General examination, laboratory investigation, and peripheral blood smear revealed anemia with leucopenia and relative lymphocytosis, thrombocytopenia, and severe neutropenia. Bone marrow biopsy revealed hypocellular bone marrow with maturation arrest at the proerythroblast stage with intranuclear inclusions and no blast and hematopoietic cells replaced by mature adipocytes in marrow spaces. Parvovirus B19 infection was confirmed by viral serology and polymerase chain reaction.

Clinical discussion

Asymptomatic or mild infection occurs most often when B19 affects immunocompetent adults. However, this is the fourth case reporting severe aplastic anemia in immunocompetent adults and the first case reported in immunocompetent adult males. The patient was admitted for close monitoring and supportive management, which effectively improved the patient's clinical condition, and discharged with a strict follow-up schedule in an outpatient setting.

Conclusion

Thus, acute infection with this virus must be considered a cause of acquired aplastic anemia even in individuals without underlying disease.

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Erythema infectiosum, often known as the fifth disease is the most common manifestation in children, whereas, in healthy adults, most cases of infection are asymptomatic or associated with arthritis and myalgia.

•The virus causes infections worldwide that vary in severity depending on the age as well as the immunologic and hematologic status of the host.

•Parvovirus infection should be considered as one of the causes of sudden and severe aplastic anemia even in previously hematologically normal individuals with intact immunity.

•Patients should be treated symptomatically until their hematopoiesis restores, and regular follow-up is critical for detecting chronic anemia or recurrence and treating it promptly.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Spectrum of adult Parvovirus B19 infection according to the underlying predisposing condition and proposals for clinical practice

The virological diagnosis of Parvovirus B19 (PvB19) infection is currently based on sero-diagnosis, molecular methods or both, yet without clear recommendations. We retrospectively identified patients with polymerase chain reaction-positive PvB19 and/or positive serological assay between 2007 and 2013. Eighty-two adults with at least one diagnostic criterion of recent PvB19 infection (IgM antibodies, viral DNA in blood and/or in marrow) were included and classified into three homogeneous groups: 30 patients had no underlying predisposing condition, 25 a hereditary haemolytic anaemia, 27 an underlying immunodeficiency. The classical PvB19-related manifestations were less frequent in immunocompromised than in immunocompetent patients (arthromyalgia: 5 vs. 14; erythema: 4 vs. 17, respectively). Only 41·4% of patients with no underlying disease were anaemic. Bicytopenia and pancytopenia were observed mainly in immunocompromised patients. Classical pure red cell aplasia was observed in only 9 of the 27 marrow smears performed. Specific IgM were found in 93% of immunocompetent patients, whereas only 58% had detectable viral DNA in blood. IgM and DNA were present alone or together in all patients with hereditary haemolytic anaemia. In immunocompromised patients, the diagnosis was confirmed by marrow analysis in 91% of cases. We make some proposals based on this large series of PvB19-infected patients.

Generalized petechial eruption induced by parvovirus B19 infection

Parvovirus infection classically causes erythema infectiosum. During the past 2 decades, other unusual skin eruptions have been noted in association with parvovirus infection. Papular purpuric gloves and socks syndrome is one form of parvovirus infection described mostly in white, young adult patients. Recently, there have been reports of a few patients with acropetechial syndrome consisting of a papular purpuric gloves and socks syndrome-like presentation with additional involvement of the perioral and chin area, temporally associated with acute parvovirus B19 infection. We report a case of a 7-year-old boy with serologic evidence of acute parvovirus B19 infection who developed a generalized petechial eruption with lesions concentrated on his extremities and face. We also reviewed the literature and summarized the various cutaneous presentations of parvovirus infection.

Persistence of human parvovirus B19 in human tissues

Human parvovirus B19 infection causes various clinical symptoms, such as rash, arthropathy, anemias and fetal death, but it can also remain asymptomatic. The arthropathies and anemias can become chronic for several years, not infrequently resembling autoimmune syndromes. B19 replicates only in red blood cell precursors of bone marrow or fetal liver, resulting in high-titred short-lived viremia, but viral DNA is detectable also in cells of several other types. Recently B19 DNA has been found, by very sensitive amplification tests, in certain tissues not only of symptomatic but also of healthy individuals for several years or decades after B19 infection. The mere presence of B19 DNA in these tissues of a symptomatic patient (e.g. joints in chronic arthritis or skin in dermatomyositis) thereby does not prove that the present disease is caused by B19. The diagnosis has to be verified by other innovative means. How and why viral DNA persists in the tissues of healthy individuals is under investigation.

Successful treatment of severe aplastic anemia associated with human parvovirus B19 and Epstein-Barr virus in a healthy subject with allo-BMT

Several reports have noted pancytopenia associated with Human parvovirus B19 (PVB19) or Ebstein-Barr virus (EBV) infections in patients who have no history of immunodeficiency. To our knowledge, we report the first case of severe aplastic anemia associated with both EBV and PVB19 infections in a previously healthy 22-year-old man. He was admitted to our hematology service due to anemia and thrombocytopenia. He had no symptoms or signs of infections of these viruses. His bone marrow biopsy revealed a hypocellular marrow. Specific IgM and IgG antibodies to EBV and PVB19 were elevated. EBV and PVB19 virus genomes were detected by PCR in the bone marrow nucleated cells and the peripheral blood lymphocytes. Two months after treatment with prednisone, acyclovir, and intravenous immune globulin (IVIg), the genomes of both these viruses disappeared. However, his transfusion requirement for platelet suspensions and packed red blood cells persisted. The patient underwent allogeneic bone marrow transplant (allo-BMT) and has had an enduring complete hematological response for 8 months.

Toxoplasmosis and parvovirus B19

Pregnant women might well improve their chances for a successful pregnancy outcome by following the advice of W. C. Fields: avoid contact with small children and animals whenever possible. Failing widespread acceptance of this philosophy, management of T. gondii and parvovirus B19 infections continues to be a challenge for the foreseeable future.

Human parvovirus B19 and blood products

BACKGROUND AND OBJECTIVES

Human B19 parvovirus (B19), identified in 1975, was only recognised as the causative agent of fifth disease in 1983. The incidence of viraemia is low, around 1 in 1,000, but is sufficient to ensure that most plasma pools for fractionation contain some virus. While infection usually occurs in childhood and is benign, chronic infection sometimes occurs and may be of concern in certain patient groups.

MATERIALS AND METHODS

This review is based on a meeting held in March 1995, and addresses recent concerns regarding the potential transmission of B19 infection by pooled plasma products.

RESULTS

Recent data on the pathophysiology and assay of this virus are summarised along with possible approaches to donor screening, product screening, and virus removal. Only five cases of symptomatic infection have been reported in persons with haemophilia, but no technology for virus removal is established, and infection may be of concern in pregnant women, and in patients with enhanced red cell turnover or who are immunosuppressed, including those infected with human immunodeficiency virus, but only rarely in immunocompetent patients.

CONCLUSIONS

For the future, well-validated assays relevant to virus infectivity are required if blood donations, plasma pools, or plasma products are to be screened, and an in-process virus inactivation step for B19 would be highly desirable. In the interim, non-plasma or recombinant products or a selective transfusion policy might be used in patient groups in which B19 infection is of particular concern. Further clinical data on the prognosis and impact of B19 infection are needed to justify both such policies and the future adoption of new technologies designed to reduce any excess B19 infectivity arising from transfused products.

Parvoviruses and bone marrow failure

Parvovirus B19, the only known human pathogenic parvovirus, is highly tropic to human bone marrow and replicates only in erythroid progenitor cells. The basis of this erythroid tropism is the tissue distribution of the B19 cellular receptor, globoside (blood group P antigen). In individuals with underlying hemolytic disorders, infection with parvovirus B19 is the primary cause of transient aplastic crisis. In immunocompromised patients, persistent B19 infection may develop that manifests as pure red cell aplasia and chronic anemia. B19 infection in utero can result in fetal death, hydrops fetalis or congenital anemia. Diagnosis is based on examination of the bone marrow and B19 virological studies. Treatment of persistent infection with immunoglobulin leads to a rapid, marked resolution of the anemia.

B19 parvovirus

B19 parvovirus is pathogenic in man and causes a variety of clinical illnesses, among them several haematological diseases. Acute infection of a host with underlying haemolysis produces transient aplastic crisis; of the midtrimester fetus, hydrops fetalis; and of an immunocompromised patient, pure red cell aplasia. The target of B19 parvovirus infection is the human erythroid progenitor cell. Infection is cytotoxic due to expression of the viral nonstructural protein. The virus can be propagated in cultures of human bone marrow, blood, and fetal liver. Humoral immunity normally terminates infection, and commercially available immunoglobulin can be used to treat persistent infection. Recombinant capsids, produced in a baculovirus system, are suitable as a vaccine reagent.

Electron microscopic identification of parvovirus virions in erythroid and granulocytic-line cells in a patient with human parvovirus B19 induced pancytopenia

In this short report we describe a patient with human parvovirus B19 (HPV B19)-induced transient pancytopenia. Parvovirus virions were seen by electron microscopy in both erythroid and granulocytic precursors. Erythroid cells are not the only targets in these cases. We draw attention to this disorder so that physicians involved with hematological disorders and transplantation be more aware of this infection.

Viruses and the blood

Haematological syndromes attributed to viruses demonstrate geographical variations in incidence and great dependence on host factors. Severe haematological disease is the exception rather than the rule in dengue virus infection, and probably depends at least in part on the host immune response to the virus. The increased incidence of hepatitis-associated aplasia in east Asia may reflect distribution of an infectious agent, an environmental toxin, or genetic predisposition, but probably represents some combination of these factors. Agents with apparently universal distribution, such as parvovirus B19 and Epstein-Barr virus, are associated with bone marrow failure only in a very narrow range of hosts. These examples teach us that viral causes cannot automatically be excluded from the differential diagnosis of syndromes whose occurrence is rare or apparently sporadic. Further investigation of these syndromes should include more detailed characterization of host factors, particularly immunological characteristics, and possible infectious and toxic cofactors which are associated with morbidity.

An amplified ELISA for the detection of parvovirus B19 IgM using monoclonal antibody to FITC

A new M-antibody capture ELISA for the detection of specific IgM against parvovirus B19 is described. The test uses a monoclonal anti-fluorescein isothiocyanate (FITC) antibody conjugated to horseradish peroxidase to amplify the positive reactions. Serum samples (N = 823) submitted for B19 IgM assay were tested in parallel in the new ELISA and the standard B19 M-antibody capture radioimmunoassay (MACRIA) test. By both tests B19 IgM was detected in 38 (4.6%) samples, and not detected in 771 (94%) samples. One sample was positive in the ELISA test but negative in the RIA and of the 13 sera giving 'equivocal' results in the MACRIA, 6 were positive and 7 negative. If the RIA equivocal results were excluded, the ELISA showed 100% (38/38) sensitivity and 99.9% (771/772) specificity compared to the MACRIA test. The B19 IgM ELISA is a sensitive and specific test with better discrimination between anti B19 IgM positive and negative specimens than MACRIA.