Biosecurity in Scandinavia

This article investigates the extent to which biosecurity measures are recognized and have been implemented in the Nordic countries, in the absence of formalized security standards and legislation. Two trials were undertaken: first, a broad combined biosafety and biosecurity questionnaire survey of the Nordic countries, and, second, a focused on-site audit of 22 facilities, with 94 laboratories, in Denmark. Both trials indicated that external security had been partially implemented but that little attention had been paid to internal security and the establishment of biosecurity. It was demonstrated that the backgrounds and identities of insiders were rarely checked and that they could have gained access to both pathogen inventory lists and freezers in many facilities. In 81% of pathogen-containing facilities, pathogens were not routinely and centrally accounted for. The authors recommend the establishment of a legal framework congruent with international standards and obligations; novel governmental national biosecurity authorities, requiring a fusion of both microbiological and technical expertise and legislative powers; and the formulation of a new code of conduct termed "Good Biosecurity Practice."

Microbial forensics for natural and intentional incidents of infectious disease involving animals

Microbial forensics is a relatively new scientific discipline dedicated to analysing microbiological evidence from a crime for attribution purposes. It builds on traditional microbiology and epidemiology but within a legal framework. Important motives for forensic investigations include interdiction of criminals, prosecution of justice, and ideally, deterrence of others from committing similar acts. Forensic capabilities in animal health should focus on building capacity for detection and reporting of increases in infectious disease morbidity and mortality among animals that might reflect a covert release of a pathogen. Suspicion should be raised when epidemiological patterns are different from those expected for the animal population and the pathogen in question. Existing capacities for the detection and reporting of epidemic and even endemic diseases should be an international priority for the prevention of catastrophic losses in animal and potentially in human life. The veterinary community needs to be more aware of the legal requirements related to forensic investigations so that veterinarians will be prepared to handle evidence properly within their own fields.

Randomized comparison of oxygen mask treatment vs. nasal continuous positive airway pressure in dengue shock syndrome with acute respiratory failure

Dengue hemorrhagic fever (DHF) is caused by dengue virus. Patients with DHF grade 3-4, termed Dengue Shock Syndrome (DSS), may develop acute respiratory failure after initial fluid resuscitation. Previously, these patients were treated with oxygen on a nasal cannula, or if necessary with tracheal intubation and mechanical ventilation. In the present prospective randomized study, we compared the effectiveness of oxygen treatment administered by a face mask vs. nasal continuous positive airway pressure (NCPAP). Morbidity, mortality, and supportive treatment was evaluated. Thirty-seven patients with DSS complicated by respiratory failure were enrolled. On admission and after 30 min of treatment, clinical and paraclinical data were obtained. Chest X-ray revealed pleural effusion in 92 per cent and showed interstitial oedema in 33 per cent. After 30 min of treatment the respiratory rate decreased significantly in the NCPAP group (p < 0.05), while SaO2 and PaO2 increased in both groups (p < 0.01). However, subsequently a significant difference of unresponsiveness to treatment between the oxygen mask group and the NCPAP group (13/19 vs. 4/18,p < 0.01) was noted. Complications of NCPAP or oxygen mask treatment were not documented. We conclude that NCPAP is useful in improving the management of acute respiratory failure in children with DHF/DSS in dengue-endemic areas.

Identification and characterization of a second novel human erythrovirus variant, A6

Parvovirus B19 (B19), currently the only accepted member of the Erythrovirus genus, is the only parvovirus known to be pathogenic in humans. Recently a viral sequence, tentatively termed V9 which showed 11% variability from the published B19 sequences, was described from a patient with aplastic crisis. To search for additional parvovirus variants, we used the new NS1/7.5EC PCR assay whose primers were designed from a conserved region of the B19/V9 sequence and encompasses an MfeI restriction enzyme site that would allow differentiation between B19- and V9-like sequences. Screening of 225 serum and bone marrow samples and 62 plasma pools identified one new atypical parvovirus sequence, A6, from an anemic HIV-positive patient. A6 exhibited 88% similarity to B19 and 92% to V9, compared to >98% correspondence between reported B19 isolates. Based on the genome similarity to B19, an RT-PCR for A6 capsid transcripts was developed and used to test for A6 infectivity of UT7/Epo/S1 cells. Despite high viral titers, A6 viral transcripts were not detected. Thus, although the prevalence of B19 variants probably is low, the true clinical significance remains unknown. Current PCR analyses are unlikely to detect novel variants without the design of specific primers to the A6/V9/B19 common sequences.

Human parvovirus B19

Parvovirus B19 (B19) was discovered in 1974 and is the only member of the family Parvoviridae known to be pathogenic in humans. Despite the inability to propagate the virus in cell cultures, much has been learned about the pathophysiology of this virus, including the identification of the cellular receptor (P antigen), and the control of the virus by the immune system. B19 is widespread, and manifestations of infection vary with the immunologic and hematologic status of the host. In healthy immunocompetent individuals B19 is the cause of erythema infectiosum and, particularly in adults, acute symmetric polyarthropathy. Due to the tropism of B19 to erythroid progenitor cells, infection in individuals with an underlying hemolytic disorder causes transient aplastic crisis. In the immunocompromised host persistent B19 infection is manifested as pure red cell aplasia and chronic anemia. Likewise, the immature immune response of the fetus may render it susceptible to infection, leading to fetal death in utero, hydrops fetalis, or development of congenital anemia. B19 has also been suggested as the causative agent in a variety of clinical syndromes, but given the common nature, causality is often difficult to infer. Diagnosis is primarily based on detection of specific antibodies by enzyme-linked immunosorbent assay or detection of viral DNA by dot blot hybridization or PCR. Treatment of persistent infection with immunoglobulin reduces the viral load and results in a marked resolution of anemia. Vaccine phase I trials show promising results.

Detection of parvovirus B19 NS1-specific antibodies by ELISA and western blotting employing recombinant NS1 protein as antigen

Human parvovirus B19 (B19) encodes a number of nonstructural proteins, including the major protein, NS1, and two structural proteins, VP1 and VP2. The use of denatured NS1 in enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) assay has provided an opportunity to study some of the immunologic properties of NS1, but the results have been equivocal and the diagnostic sensitivity poor, probably because of the absence of conformational epitopes. Various viral isolates and baculovirus vectors were employed to produce recombinant B19 NS1 under nondenaturing conditions for the first time. To assess the antigenicity of purified B19 NS1, the reaction patterns of 252 samples were compared by B19 NS1 and VP2 ELISA. In sera from individuals with past infection (VP2 IgG-positive), the use of this new antigen increased significantly the sensitivity of ELISA compared with WB (78% vs. 33%, P = 0.001), contradicting perpetuated claims that B19 NS1 IgG is detected primarily in patients with arthralgia or chronic infection. Previous reports of the absence of NS1 IgG during the initial phase of infection (< 6 weeks) were proved incorrect by the detection of NS1 IgG in 60% of samples from patients recently infected by B19. Including conformational epitopes in the ELISA increases the diagnostic sensitivity, although immunologically, a temporal (years) attenuation of NS1 antibodies appears to take place. This novel diagnostic tool may be useful as a supplement in case of borderline results by VP2 ELISA and for monitoring the efficacy of future capsid-based B19 vaccines.

Serologic study on parvovirus b19 infection in childhood acute lymphoblastic leukemia during chemotherapy: clinical and hematologic implications

PURPOSE

To present a first descriptive serologic study on the clinical and hematologic implications of parvovirus B19 (B19) infection in children with acute lymphoblastic leukemia from the time of initial admission until discontinuation of chemotherapy.

PATIENTS AND METHODS

Seventy-five patients were studied by polymerase chain reaction, enzyme-linked immunosorbent assay, sequencing, and immunodiffusion.

RESULTS

During the period of observation, 8% (4/48) of B19-seronegative patients seroconverted and infection triggered profound anemia and thrombocytopenia. B19-specific IgG disappeared in 26% (8/31) of B19-seropositive patients, and these patients were significantly younger and the B19 IgG titers were lower on admission compared with patients who continuously displayed B19 IgG. B19 DNA was detected in the seroconverting patients, and this helped in determining the time of infection, which coincided with a B19 epidemic in 75% (3/4) of patients. Patients typically presented with fever and myalgia; a rash, indicative of B19 infection, was observed in only one patient.

CONCLUSIONS

B19 infection was able to mimic a leukemic relapse or therapy-induced cytopenia and led to hospital admission, frequent blood sampling, renewed bone marrow aspirates, multiple transfusions of red blood cells or platelets, and cessation of maintenance chemotherapy for up to 3 weeks. The peculiar disappearance of B19-specific IgG, which could not be ascribed to a generalized low level of serum immunoglobulins, has not been previously reported. The results indicate that B19 should be assayed at diagnosis of leukemia to avoid subsequent diagnostic uncertainty, and during treatment in B19-seronegative patients exhibiting unexplained cytopenia.

Prevalence of parvovirus B19 and parvovirus V9 DNA and antibodies in paired bone marrow and serum samples from healthy individuals

Parvovirus B19 (hereafter referred to as B19) exhibits a marked tropism to human bone marrow (BM), and infection may lead to erythema infectiosum, arthropathy, hydrops fetalis, and various hematologic disorders. Recently, a distinct parvovirus isolate termed V9 with an unknown clinical spectrum was discovered. In contrast to the many studies of B19 serology and viremia, valid information on the frequency of B19 or V9 DNA in the BM of healthy individuals is limited. To develop a reference value, paired BM and serum samples from healthy subjects were tested for the presence of B19 and V9 DNA and specific antibodies. Immunoglobulin M (IgM) was not found in any of the serum samples. The prevalence of IgG showed a gradual and steady increase from 37% in children aged 1 to 5 years to 87% in people aged >50 years. When 190 well-characterized subjects were examined, B19 DNA was detected in the BM of 4 individuals (2.1%; 95% confidence interval, 0.58 to 5.3%) while none of the paired serum samples showed evidence of circulating viral DNA. V9 DNA was not found in any of the BM or serum samples. The finding of B19 DNA probably indicated a primary infection in one 7-year-old individual and reinfection or reactivation of persistent infection in the remaining three persons, aged 47 to 58 years. Serving as a benchmark for future studies, these findings are useful when interpreting epidemiologic data, performing BM transplantation, or considering clinical implications of parvovirus infection.

Baculovirus expression of erythrovirus V9 capsids and screening by ELISA: serologic cross-reactivity with erythrovirus B19

Diagnosis of erythrovirus B19 (B19) relies on serology and the detection of viral DNA. Recently, a distinct erythrovirus isolate termed V9, markedly different from erythrovirus B19 (> 11% nucleotide disparity), was isolated. Standard B19 PCR assays were inconclusive and serologic tests failed to categorize V9 as an acute B19-like infection. Sequencing, combined with PCR studies, have since demonstrated the need for specific and differentiated techniques when examining samples for possible B19 or V9 viremia. The antigenic properties of the V9 capsid proteins have not been characterized previously. To address this question, V9 VP1 and VP2 open reading frames were cloned and expressed in insect cells using a baculovirus vector. Large quantities of purified recombinant V9 capsid protein were produced and electron micrographs revealed self-assembly of V9 VP1/VP2 and VP2 capsids into empty icosahedral erythrovirus-like particles with a diameter of approximately 23 nm. Screening of a panel of 270 clinical samples for the presence of V9 IgM and IgG antibodies in ELISA showed 100% serologic cross-reactivity between B19 and V9 when comparing V9 VP2 capsids to a commercial B19 VP2 assay. This suggests that both a V9 and a B19 antibody response may be diagnosed equally well by ELISA using either V9 or B19 recombinant capsids as antigen source. Retrospectively, translation of the V9 sequence indicates that despite a significant genetic variation on the DNA level, the majority of the discrepant DNA sequence represents silent mutations leading to an amino acid sequence very similar to the known B19 strains (96-97% homology).

Parvovirus B19 and parvovirus V9 are not associated with Henoch-Schönlein purpura in children

BACKGROUND

Based on single case reports, parvovirus B19 (B19) has repeatedly been proposed as an etiologic agent in patients with Henoch-Schönlein purpura (HSP), perhaps causing vasculitis by direct invasion of vascular endothelial cells because of the tissue distribution of the cellular B19 receptor. A cohort of children with HSP and other vasculitic diseases was investigated and compared with healthy control children to assess the role of B19 as well as parvovirus V9 (a putative emerging B19-like virus).

PATIENTS AND METHODS

Serum samples from 36 children with HSP (n = 29) or other vasculitic diseases (n = 7) were examined, and 38 healthy bone marrow donors were used as controls. The presence of specific B19 and V9 IgM and IgG antibodies was determined with a recently developed enzyme-linked immunosorbent assay, and viral DNA was detected by a novel nested PCR.

RESULTS

Specific IgM was not present in any of the patient or control serum samples. B19 DNA was detected in one patient, a previously healthy 8-year-old boy diagnosed with HSP, whereas none of the controls was B19-positive. V9 was not detected in any of the clinical or control samples. It seems likely that B19 infection might have triggered the development of HSP in the B19-positive patient, because B19 viremia is otherwise uncommon.

CONCLUSIONS

Although causality is difficult to construe in single cases, the data indicate that B19 is not a common contributing factor in the pathogenesis of vasculitis and that this pathogen is only rarely associated temporally with HSP or vasculitic diseases in children.

Prospective case-control study of encephalopathy in children with dengue hemorrhagic fever

We present a prospective case-control study of 27 serologically confirmed dengue hemorrhagic fever (DHF) patients with severe central nervous system symptoms. Dengue associated encephalopathy accounted for 0.5% of 5,400 patients admitted with DHF. The mortality rate among children with encephalopathy was 22%, with the survivors experiencing a complete recovery. Liver enzymes and bilirubin were significantly elevated in the study group. In analysis of the cerebrospinal fluid (CSF), reverse transcriptase-polymerase chain reaction revealed dengue-3-specific RNA in one evaluated case. Dengue-specific immunoglobulin M was detected in CSF in 14 of 22 assessable patients, indicating a localized infection. Magnetic resonance imaging scans showed cerebral edema in the majority of patients, although encephalitis-like changes were less common. There was an equal distribution of primary and secondary infections. On the basis of previous reports and of the findings of our study, DHF probably encompasses an expanding clinical spectrum that infrequently involves encephalitis due to a direct neurotropic effect of dengue virus.

Novel PCR assay for differential detection and screening of erythrovirus B19 and erythrovirus V9

Diagnosis of erythrovirus B19 relies on serology and the detection of viral DNA. These techniques were believed to detect all field isolates because erythrovirus B19 has been known to undergo little genetic variation (1-2%). Recently, a distinct erythrovirus isolate termed V9, markedly different from erythrovirus B19 (>11% nucleotide disparity), was isolated from a child in France suffering from transient aplastic anemia. Standard PCR assays and serological tests failed to demonstrate an acute erythrovirus B19 infection. Subsequent sequencing of the erythrovirus V9 genome shows that the nucleotide discrepancies encompass the entire genome, indicating that standard erythrovirus B19 PCR assays will not reliably detect erythrovirus V9 DNA. As a tool for studying the epidemiological role and medical importance of this erythrovirus variant, a PCR assay is described that allows simultaneous detection of, and distinction between, erythrovirus B19 and the V9 isolate. Examination of 100 erythrovirus B19 IgM positive samples as well as plasma pools representing 100,000 Danish blood donor units for the presence of B19 and V9 DNA was performed. Despite the apparent absence of erythrovirus V9 in the clinical samples at present, the DNA sequence variability demonstrates that the erythrovirus group may be more divergent than thought previously and the child harboring this isolate may herald erythrovirus V9 as a possible emerging virus.

Transient pancytopenia preceding acute lymphoblastic leukaemia (pre-ALL) precipitated by parvovirus B19

A preleukaemic phase, typified by pancytopenia and bone marrow (BM) hypoplasia, is an uncommon but well-documented prelude to acute lymphoblastic leukaemia (pre-ALL) in children. Parvovirus B19 (B19) exhibits a marked tropism to human BM and replicates only in erythroid progenitor cells acting as a confounding, but treatable agent in immunocompromised patients. We present the first case of B19-associated pre-ALL characterized by severe and recurring transient pancytopenia in a child who developed ALL 5 months later. The advent of B19-specific IgG at the time of infection and the subsequent disappearance 1.5 years later has not previously been described. In this patient the observed cytopenias were probably the result of B19 acting in concert with the failing BM and B19 is possibly one of several factors capable of triggering the onset of pre-ALL.

Parvovirus B19 transmitted by bone marrow

We describe a case of symptomatic parvovirus B19 infection transmitted by bone marrow (BM). The infection caused prolonged anaemia, thrombocytopenia, arthralgia and erythema infectiosum in a 16-year-old girl with acute myeloid leukaemia receiving a BM transplant (BMT). The BM donor was a 19-year-old asymptomatic brother who had parvovirus B19 viraemia at the time of BM harvest. Sequencing of the VP2 gene from the patient and the donor showed a perfect match of DNA sequences, confirming the mode of transmission. Parvovirus B19 represents a potential complicating factor in patients undergoing BMT, but screening by polymerase chain reaction (PCR) of donor BM may reduce the risk of infection.

[Dengue fever and dengue hemorrhagic fever]

Dengue virus is transmitted by mosquitoes and causes dengue fever/dengue haemorrhagic fever throughout the tropical areas of the world. There is an increasing incidence of dengue infections. Because of increasing travel activity, infection among Danes travelling abroad as well as imported cases are expected to be seen more frequently. In this review we describe the clinical manifestations, diagnosis, pathogenesis, treatment and prevention of the disease.

[Thrombocytopenia caused by Parvovirus B19 infection in a child with acute lymphatic leukemia]

A three-year-old boy was diagnosed with acute lymphoblastic leukemia. Two years later, while on maintenance chemotherapy, the patient was readmitted due to thrombocytopenia. The thrombocytopenia was caused by parvovirus B19 infection as evidenced by the finding of specific DNA in serum and bone marrow samples. Previous reports have highlighted the role of parvovirus B19 as a haematological pitfall and the present case shows that this virus has the potential to mimic a leukemic relapse.

The role of parvovirus B19 infection in childhood acute lymphoblastic leukemia

The authors hypothesized that parvovirus B19 with its hematotropic effects has the potential to precipitate varying forms of cytopenia in patients prior to or at the diagnosis of acute lymphoblastic leukemia (ALL). Consequently, and in view of the increasing number of cases reported, this retrospective study evaluated, for the first time, the possible role of parvovirus B19 infection in pediatric patients suffering from ALL, by investigating the frequency and clinical relevance of this infection at the time of the malignant diagnosis or, when applicable, during a phase of pre-ALL. Furthermore, a review of reported parvovirus B19 infections in pediatric ALL patients is presented. The serum of 65 consecutive pediatric patients with a diagnosis of ALL was examined for possible parvovirus B19 infection employing the polymerase chain reaction and ELISA techniques. Specific IgG was demonstrated in 30% of the patients. One patient diagnosed with pre-ALL had evidence of parvovirus B19 DNA in the serum during pancytopenia 5 months prior to the onset of ALL. The results suggest that there is an insignificant chance of finding a parvovirus B19 infection in pediatric patients with ALL at the time of diagnosis. However, parvovirus B19 infection may infrequently serve as a prodrome to ALL.

Role of parvovirus B19 infection in childhood idiopathic thrombocytopenic purpura

Although parvovirus B19 exhibits a strong tissue-tropism for erythroid progenitor cells leading to anaemia, several case reports indicate that parvovirus B19 infection may also cause the development of thrombocytopenia. Despite recent studies, the frequency and clinical relevance of this association have remained questionable. Consequently, and in view of the paucity of evidence regarding a viral aetiology for idiopathic thrombocytopenic purpura (ITP), we examined the role of parvovirus B19 in 47 children with newly diagnosed ITP. Specific viral DNA indicating a current or recent parvovirus B19 infection was demonstrated in 6 of 47 patients (13%) employing the polymerase chain reaction technique. Our study suggests that children with ITP and associated parvovirus B19 infection are characterized by acute onset of profound thrombocytopenia. Among the parvovirus B19 positive children, duration of disease was brief in three children treated with immunoglobulin but chronic in the remaining three patients given high-dose steroids. Prospective studies are needed to confirm these initial observations. This virus should be considered as a possible aetiologic agent in some children with ITP.

Parvovirus B19 infection associated with myocarditis following adult cardiac transplantation

A 56-year-old woman underwent an uneventful cardiac transplantation due to dilated cardiomyopathy. One week later the patient developed clinical and histological signs of myocarditis. We report for the first time a case of myocarditis in an adult heart transplant recipient, possibly induced by parvovirus B19, as evidenced by the finding of specific IgM in serum and specific DNA in the myocardial cells. Furthermore, this is the first time parvovirus B19 DNA has been observed in the myocardium of an adult. In conclusion, parvovirus B19 should be recognized as a potential pathogen causing myocarditis in heart transplant recipients. In order to establish a definite and rapid diagnosis, a search for specific IgM should be supplemented with PCR investigations of serum and myocardial biopsies when available.

Parvovirus B19 infections in patients with chronic anemia

BACKGROUND AND OBJECTIVE

Parvovirus B19 has a marked tropism for erythroid progenitor cells and this may lead to chronic anemia in predisposed individuals. It was the purpose of the present study to investigate prospectively the frequency of parvovirus B19 infections in patients with a diagnosis of chronic anemia.

METHODS AND RESULTS

Evidence of parvovirus B19 infection was found in 13/43 (30%) patients by demonstrating viral DNA and/or specific IgM antibodies through the use of PCR and ELISA techniques. Parvovirus B19 infection was established in 4 of 7 patients with hemolytic anemia, in 2 of 3 patients with pure red cell aplasia, in 2 of 9 patients with myelodysplastic syndrome, and in 2 of 10 patients with aplastic anemia. In 8 of the 13 positive patients only parvovirus B19 DNA could be detected, while 4 patients tested positive for both parvovirus B19 DNA and specific IgM. In the remaining positive patient only specific IgM could be detected.

CONCLUSIONS

Since no predictive paraclinical or clinical features were observed we recommend that all cases of chronic anemia be tested for the presence of parvovirus B19 infection. Due to the discrepancies between DNA and IgM results, the diagnostic procedures should include a search for specific DNA by PCR methods if specific IgM has been found to be negative.

Parvovirus B19 infection and Diamond-Blackfan anaemia

It is the purpose of the study to report the frequency of parvovirus in children with a diagnosis of Diamond-Blackfan anaemia and to discuss the possible aetiological role of parvovirus in Diamond-Blackfan anaemia. We found parvovirus DNA in 3 of 11 bone marrow smears. Giant pronormoblasts showed low sensitivity (33%) and poor specificity (75%). The presence of giant pronormoblasts was associated with a very high myeloid:erythroid ratio, and may not be specific for parvovirus infection, but a feature of severely suppressed erythropoiesis. The three parvovirus-positive patients were the only children who experienced a remission, and who are free of medication. The seven surviving parvovirus-negative patients are all currently on steroid treatment.

Parvovirus: the expanding spectrum of disease

Treatment of parvovirus infections among immunocompromised hosts using immunoglobulin has provided the clinician with a useful therapeutic tool but has also highlighted the problems concerning chronic disease states. The discovery of the human parvovirus B19 in 1975 and subsequent studies of its effects in humans have identified this virus as the causative agent of a broad spectrum of diseases. Recent improvements regarding the development of sensitive PCR techniques and methods for cultivation have provided new insight into its pathogenic role, its virology and immunology, and the varied clinical manifestations. The current state of knowledge concerning parvovirus enabled us to divide the long list of diseases caused by this virus into three main categories: (1) disease found among normal hosts (asymptomatic disease, erythema infectiosum, arthropathy, hydrops fetalis), (2) hematologic diseases (aplastic crisis, chronic anemia, idiopathic thrombocytopenic purpura, transient erythroblastopenia of childhood, Diamond-Blackfan anemia) and, finally, (3) a heterogeneous group of diseases, in which the etiologic role of parvovirus is less clear and sometimes putative (neurologic disease, rheumatologic disease, vasculitic and myocarditic syndromes). In particular, arthropathy, hydrops fetalis and the hematologic disorders may be of pediatric concern. Consequently, it is of paramount importance that in all of these cases the clinician includes parvovirus as a differential diagnosis.

Parvovirus B19 infection associated with encephalitis in a patient suffering from malignant lymphoma

A parvovirus B19 infection was established in a 58-year-old woman undergoing treatment for malignant lymphoma. Clinically, the patient displayed a variety of neurologic symptoms that could not readily be explained by the mere presence of lymphoblastic cells within the central nervous system. This is the first time parvovirus B19 DNA has been detected in the cerebrospinal fluid of a patient suffering from encephalitis.

Chronic parvovirus infection mimicking myelodysplastic syndrome in a child with subclinical immunodeficiency

PURPOSE

We present a report of a child with subclinical immunodeficiency who became chronically infected with parvovirus resulting in pancytopenia and morphologic abnormalities in the bone marrow mimicking myelodysplastic syndrome (MDS).

PATIENTS

An 8-year-old boy presented with severe anemia, moderate thrombocytopenia and granulocytopenia. The patient showed hyper-immunoglobulin M (IgM) immunodeficiency but no increased susceptibility to infections. The bone marrow was hypercellular with dysplastic granulocytopoiesis and erythroblastopenia.

RESULTS

Treatment with cyclosporine and i.v. Ig resulted in temporary normalization of the hemoglobin level. For several years it was assumed that the patient had MDS. A diagnosis of parvovirus infection was initially rejected due to the lack of specific antibodies and the absence of giant pronormoblasts in the bone marrow. When the polymerase chain reaction technique became available, parvovirus DNA was detected from the entire disease course.

CONCLUSIONS

This case report expands our conception of the clinical spectrum of parvovirus infection and emphasizes that parvovirus must be considered as a differential diagnosis in MDS. We recommend performing a parvovirus DNA test despite negative serologic findings in patients with MDS, especially when associated with immunologic abnormalities.

Estimation of serum concentration of parvovirus B19 DNA by PCR in patients with chronic anaemia

Parvovirus B19 DNA was detected in serum samples from 10 out of 42 patients with chronic anaemia, the majority of whom suffered from aplastic anaemia, haemolytic anaemia, pure red cell anaemia or myelodysplastic syndrome. Nested PCR methods with sensitivities of 0.005-0.05 fg DNA were developed. In nine patients, B19 DNA could only be detected by nested PCR. Conventional PCR with a sensitivity of 50 fg B19 DNA could only detect B19 DNA in one patient. In the majority of B19-DNA-positive patients, the DNA concentration was estimated at 0.005-0.05 fg per 5 microliters serum.