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.

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.

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.

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]. / Denguefeber og dengue haemorragisk feber.

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.

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.

[Thrombocytopenia caused by Parvovirus B19 infection in a child with acute lymphatic leukemia]. / Trombocytopeni forårsaget af parvovirus B19-infektion hos et barn med akut lymfatisk leukaemi.

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.

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.