B19 Antibodies Research Articles

Symptoms Associated with Parvovirus B19 Infection in Adults: A Pilot Study

The clinical features of parvovirus B19 infection in adult patients have not been well described. The aim of this prospective study was to clarify the clinical features of adult patients with parvovirus B19 infection in primary care settings. The study subjects were adults over age 18 years who had visited one primary care clinic over a period of one year. They were chosen if they had at least two of the following three symptoms: edema, joint pain, and rash, and if they had contact with children with erythema infectiosum. The diagnosis was confirmed if anti-parvovirus B19 antibodies were identified. The process of these symptoms was recorded until they resolved. Twenty patients met the inclusion criteria, and 14 (70%) patients were diagnosed with parvovirus B19 infection. The 14 adult patients consisted of two men and twelve women ranging from 33 to 63 years (median, 38 years). The patients consisted of two groups. In the first group, they presented with the first phase of infection showing symptoms such as malaise, muscle pain, and fever, and in the second phase presented with edema, rash, and joint pain that developed within two days of the first phase. In the second group, the first and second phases were clearly separated. Parvovirus B19 infection in adults can be efficiently diagnosed in primary care settings by observing clinical symptoms such as edema, joint pain, and rash, and by asking patients about their contact with children who have erythema infectiosum.

Persistent Anemia in a Patient with Diffuse Large B Cell Lymphoma: Pure Red Cell Aplasia Associated with Latent Epstein-Barr Virus Infection in Bone Marrow

We report a case of pure red cell aplasia (PRCA), which was initially suspected as a result of bone marrow involvement of diffuse large B cell lymphoma. Persistent anemia without an obvious cause was observed in a 47-yr-old man diagnosed with relapsed diffuse large B cell lymphoma. The bone marrow study showed only erythroid hypoplasia without the evidence of bone marrow involvement with lymphoma cells, thus PRCA was suggested. However, parvovirus infection was excluded as a potential cause of PRCA because of negative IgM anti-parvovirus B19 antibody and negative parvovirus PCR in the serum. Latent Epstein-Barr virus (EBV) infection of bone marrow was suggested by in situ hybridization with EBV-encoded small RNA (EBER) that showed a strong positive expression in bone marrow cells. Thus, PRCA was thought to be associated with latent EBV infection in bone marrow cells. Although the finding of unexplained anemia is a possible predictor of bone marrow involvement with lymphoma cells, PRCA as a result of a viral infection including EBV should be considered in lymphoma patients. This is the first report of the occurrence of PRCA associated with latent EBV infection in a patient with non-Hodgkin's lymphoma.

Parvovirus B19 infection in pregnancy: maternal and fetal viral load measurements related to clinical parameters

To correlate quantitative maternal and fetal parvovirus B19 (B19V) viral loads and antibody levels at intrauterine transfusion (IUT) as a predictor of fetal morbidity. Prospectively collected clinical data and quantitative B19V viral load and specific IgM and IgG values in fetal and maternal blood samples taken during IUT. Maternal IgM and IgG levels exceeded fetal antibody levels. Fetal viral load measurements correlated positively with maternal viral loads and exceeded maternal viral load 10(5)-fold (p < 0.0001). Maternal B19V IgM and fetal B19V viral load showed a positive correlation (r = 0.840, p = 0.007). No relation was found between fetal viral load and severity of fetal anemia derived from Doppler flow measurements in the middle cerebral artery. Maternal and fetal B19V viral load values are highly interrelated, suggesting continuous maternal and fetal viral replication or a fetal source of maternal viremia. Maternal B19V IgM values may predict the severity of fetal infection, but the severity of B19V induced fetal anemia cannot be predicted using fetal or maternal viral loads. Fetal ultrasound remains the gold standard for identifying fetal anemia in B19V infection.

Calcium-mediated Transient Phosphorylation of Tau and Amyloid Precursor Protein Followed by Intraneuronal Amyloid-β Accumulation

Intraneuronal accumulation of hyperphosphorylated protein tau in paired helical filaments together with amyloid-beta peptide (Abeta) deposits confirm the clinical diagnosis of Alzheimer disease. A common cellular mechanism leading to the production of these potent toxins remains elusive. Here we show that, in cultured neurons, membrane depolarization induced a calcium-mediated transient phosphorylation of both microtubule-associated protein tau and amyloid precursor protein (APP), followed by a dephosphorylation of these proteins. Phosphorylation was mediated by glycogen synthase kinase 3 and cyclin-dependent kinase 5 protein kinases, while calcineurin was responsible for dephosphorylation. Following the transient phosphorylation of APP, intraneuronal Abeta accumulated and induced neurotoxicity. Phosphorylation of APP on Thr-668 was indispensable for intraneuronal accumulation of Abeta. Our data demonstrate that an increase in cytosolic calcium concentration induces modifications of neuronal metabolism of APP and tau, similar to those found in Alzheimer disease.

Current epidemiological aspects of human parvovirus B19 infection during pregnancy and childhood in the western part of Germany

This investigation was undertaken to provide detailed information on the epidemiology of human parvovirus B19 (B19) infection during pregnancy and childhood in the western part of Germany. Between 1997 and 2004, 40,517 sera from pregnant women aged 17-45 years and 6060 sera from children and young adults were tested for B19 IgG and IgM in our laboratory. In pregnant women, both the history of a 'specific' (OR 7.7, 95% CI 5.2-11.4) and a 'non-specific' rash (OR 3.3, 95% CI 1.5-7.1) was predictive for B19 IgM positivity. The B19 IgG prevalence was 69.2% (4097/5924) in a subgroup of asymptomatic pregnant women screened for B19 antibodies. In children, the age-specific IgG-positivity rate increased from 12.2% (66/541) at 2 years of age to 71.9% (396/551) in those older than 10 years. In conclusion, the prevalence of B19 IgG in pregnant women from the western part of Germany is higher then previously reported. Contact with children aged 3-10 years is a major risk factor for exposure to B19. Pregnant women with the history of a 'non-specific' rash should also be evaluated for acute B19 infection.

Effects of transfusion on human erythrovirus B19‐susceptible or ‐infected pediatric recipients in a genotype 3–endemic area

Human erythrovirus (parvovirus) B19 is transmitted by transfusion of blood, blood components, and plasma derivatives and is resistant to most viral inactivation methods. B19 genotype 3 is prevalent in Ghana, and no related clinical information is available. This study assessed the transmission of B19 genotype 3 by transfusion and the potential effect of transfused B19 antibodies in viremic recipients. Immunological aspects of B19 genotype 3 infection in children mainly transfused for acute malarial anemia were examined. Molecular and serologic methods adapted to genotype 3 were developed and used. Among 114 donor-recipient pairs from Ghana, two donations contained B19 DNA and specific antibodies, and no evidence of transmission was found. B19 immunoglobulin G (IgG)-containing whole blood was transfused to 14 B19 DNA-positive recipients. Three recipients with detectable levels of IgG to B19 failed to clear viremia 1 to 2.3 months after transfusion. Ten recipients without IgG to VP2 before transfusion cleared the virus but failed to develop an immune response to B19 within 1 to 2 months after transfusion. Only 1 patient who received little specific IgG by transfusion produced detectable antibodies. Low levels of B19 genotype 3 DNA associated with specific IgG are not infectious by transfusion. Viral clearance and apparent down regulation of immune response to B19 may be related to removal of the viral antigens by transfused antibodies and/or immunomodulatory effect of transfusion.

Prevalence of anti-human parvovirus B19 IgG antibody among blood donors in Jilin province

To investigate the prevalence of the parvovirus B19 infection among the blood donors in Jilin province to provide the basic data to evaluate the epidemics of B19 virus in China. Indirect ELISA was used to detect IgG antibody against parvovirus B19 in the sera from blood donors. In a total of 184 serum samples, IgG antibody was detected in 55.43% samples, antibody positive rate in female was significantly higher than that in male (P<0.05) and the positive rate peaked at 35-45 years age group. These data illustrate that the prevalence of the B19 antibody in blood donors of Jilin province was high, and it is therefore necessary to detect the B19 DNA to ensure the blood safety.

Incidence of parvovirus B19 infection among an unselected population of pregnant women in the Netherlands: A prospective study

Objective To evaluate seroprevalence of anti-parvovirus B19 IgG immunoglobulins and the rate of seroconversion in seronegative pregnant women. Design Prospective assessment of anti-parvovirus B19 IgG immunoglobulins in an unselected population of pregnant women booked for antenatal care from 1998 to 2000. Setting Maternity departments of an academic hospital and four affiliated teaching hospitals in the Netherlands. Subjects Two thousand five hundred and sixty seven pregnant women. Main outcome measures Seroprevalence of anti-parvovirus B19 IgG immunoglobulin in the first trimester of pregnancy and subsequent seroconversion in those women who were tested negative for parvovirus B19 antibodies in the first trimester of pregnancy. Results The estimated seroprevalence of anti-parvovirus B19 IgG immunoglobulins among the study population is 70% (95% CI: 68–71) in the first trimester of pregnancy. Seven hundred and seventy nine women tested negative for parvovirus B19 antibodies in the first trimester of pregnancy. Paired testing in these women confirmed 18 seroconversions. Based on these findings the estimated incidence of maternal parvovirus B19 infection in this population among seronegative Dutch women is 2.4% (95% CI: 1.4–3.7). Conclusion Maternal infection with parvovirus B19 is relatively common. However, it is argued that in the Netherlands routine assessment of parvovirus antibodies in pregnant women is not warranted as there is a low risk of adverse fetal outcome and measures to prevent the parvovirus B19 infection and its consequences are very limited.

Exposure of hematologic patients to parvovirus B19 as a contaminant of blood cell preparations and blood products

Patients with hematologic malignancies often require blood products, and parvovirus B19 is known to be transmitted by this route. Primary infection with parvovirus B19 shows a wide variety of disease manifestation. In immunocompromised patients, symptoms are severe and viral clearance is delayed or missing. A total of 2123 blood products given to all patients of a hematologic ward over a period of 6 months were retrospectively examined for the presence of parvovirus B19 DNA by an in-house real-time polymerase chain reaction (PCR; TaqMan). Patients who had received B19 DNA-positive blood products were further investigated serologically and by PCR for the presence of parvovirus B19 antibodies and DNA. Twenty-one (1%) of 2123 blood products tested positive for the presence of B19 DNA (2% of pooled products, 0.7% of single-donor products, and 17.6% of allogeneic peripheral blood progenitor cells), the median viral load was 700 genome equivalents per mL. During the study period, 114 patients were treated on the ward, and 14 (12%) of them received B19 DNA-positive blood components. None of them developed symptoms of an acute B19 infection, although one had a short low-level viremia. Although B19 DNA was detected in 1 percent of blood products given to hematologic patients, the exposure of 12 percent of patients did not result in symptomatic infections.

Infections par des virus transmissibles par le sang chez des hémophiles en Tunisie

In this work, we proposed to evaluate prevalences of hepatitis B and C viruses and Parvovirus B19 among 70 Tunisian haemophiliacs treated with clotting factors imported from Europe and/or locally produced cryoprecipitate; among them 6 (8.6%) are known HIV positive patients. HBs antigen, anti-HBc antibodies and anti-Parvovirus B19 antibodies were detected in 7.1%, 52.9% and 91.8%, respectively. HCV prevalence, defined as positive ELISA with positive Immunoblot and/or PCR was 50.0%. Prevalences of these viral infections in haemophiliacs are higher than prevalences detected among general population and in the control group of the study. HCV infection is less frequent in haemophiliacs born after 1985, the year of introduction of the inactivation procedures in the production of coagulation factors concentrates; it decreases more considerably after 1994, date of introduction of systematic screening of HCV among blood donors. In contrast, despite the inactivation of the factors concentrates and the systematic screening of the blood donations against HBs antigen, since 1973, the risk of HBV infection contamination remains high in the Tunisian haemophiliacs. The introduction in 1995 of hepatitis B vaccination in the national schedule of new-born vaccination may resolve in the future the problem of HBV infection in haemophiliacs and in the other categories of the Tunisian population.

Parvovirus B19 viral loads in relation to VP1 and VP2 antibody responses in diagnostic blood samples

Background: Human parvovirus B19 infection is characterised by high peak viral load levels followed by episodes of prolonged viremia. The risk of transmission of parvovirus B19 by blood or blood products has been increasingly recognised and parameters that can predict the risk of transmission are subject of interest. Objectives: This study aimed to study correlations between B19 viral DNA loads and antibody responses to the viral antigens VP1 and VP2 in clinical serum samples. Study design: A panel of 1610 serum samples from patients clinically suspected from acute B19 infection were analysed. Antibodies were measured by the parvovirus anti-VP1 immuno-fluorescence assay (IFA) and the anti-VP2 enzyme immunoassay (EIA) from Biotrin. B19 viral loads were measured by a real-time PCR using the external WHO standard for DNA quantification. Results: Positive IgM responses were found in 154 (9.6%) of the 1610 sera tested. Based on the PCR results in a subset of 312 sera, the anti-VP2 EIA IgM showed a better combination of sensitivity/specificity (91%/94%) compared to the anti-VP1 IFA (66%/97%). B19 DNA levels in the sera strongly correlated with the levels of IgM antibodies, all sera with high viral loads (>10 6 IU/ml) having VP2 EIA IgM ratios above 3.0. Conclusions: The B19 VP2 IgM ELISA is superior to the B19 VP1 IgM IFA if verified by PCR. Anti-VP2 IgM antibodies in sera are indicative for the presence B19 DNA and can be used to predict high levels of B19 DNA in diagnostic sera.

Parvovirus B19 transmission by a high‐purity factor VIII concentrate

Parvovirus B19 (B19) is known to cause a variety of human diseases in susceptible individuals by close contact via the respiratory route or by transfusion of contaminated blood or blood products. In this study, whether a case of B19 transmission was causally related to the infusion of implicated lots of a solvent/detergent (S/D)-treated, immunoaffinity-purified factor VIII concentrate (antihemophilic factor [human][AHF]) was investigated. Anti-B19 (both immunoglobulin M [IgM] and immunoglobulin G [IgG]) and B19 DNA (by a nucleic acid testing [NAT] procedure) were assayed in two implicated product lots, a plasma pool, and a recipient's serum sample. Analysis of the partial B19 sequences obtained from sequencing clones or direct sequencing of the samples was performed. Only one of the two implicated lots was B19 DNA-positive. It contained 1.3 x 10(3) genome equivalents (geq or international units [IU]) per mL. The negative lot was derived from plasma screened for B19 DNA by NAT in a minipool format to exclude high-titer donations, whereas the positive lot was mostly from unscreened plasma. This high-purity AHF product had no detectable anti-B19 IgG. A 4-week postinfusion serum sample from a recipient, who received both lots and became ill, was positive for the presence of B19 antibodies (both IgM and IgG) as well as B19 DNA. The B19 sequences from the positive lot, its plasma pool, and the recipient's serum sample were closely related. These findings and the recipient's clinical history support a causal relationship between the implicated AHF product and B19 infection in this recipient. The seronegative patient became infected after receiving 2x10(4) IU (or geq) of B19 DNA, which was present in this S/D-treated, high-purity AHF product.

Acute Chest Syndrome Is Strongly Associated Parvo Virus B19 Seroconversion in Patients with Hemoglobin SC Disease.

Parvovirus B19 replicates principally in human erythrocyte precursors resulting in temporary cessation of erythropoiesis. In patients with sickle hemoglobinopathies, parvovirus B19 infection has been associated with acute chest syndrome and may lead to transient aplastic crisis. Evidence of prior infection with parvovirus B19 is found in 50 to 60% of adults. Infection appears to be followed by lifelong immunity. The objectives of the Study of Seroprevalence and Incidence of Parvovirus B19Infection in Children with Sickle Hemoglobinopathies are to determine the prevalence of parvovirus B19 antibodies in children less than 16 years old; determine the rate of parvovirus B19 seroconversion; and determine whether parvovirus B19 seroconversion is associated with the occurrence of aplastic crisis or acute chest syndrome. Between April 2000 and June 2002 a total of 1039 children from eight Comprehensive Sickle Cell Centers (CSCC) were enrolled in the study and 898 had at least one follow up visit. Participants ranged in age from <1 month to 16 years at enrollment (mean age 7.2, + 4.5 years), 47% were female, 53% were male. 67% had homozygous Hb SS disease, 24% had Hb SC disease, 6% had Hb SB+ disease, 3% had Hb SB0 disease, and <1% had other S sickle cell disease. The seroprevalence of parvovirus B19 in the cohort was 35%. Prevalence varied significantly by age, ranging from a low of 8% for children 1–2 years of age to 69% for children 13+ years of age (p<0.0001). The greatest increase in seroprevalence occurred between 6 and 7 years of age. Adjusted for age, there were no significant differences in seroprevalence by gender, clinical center, geographic area of residence (northeast, southeast, midwest, and west) sickle hemoglobinopathy, number of siblings, hemoglobin level, reticulocyte %, or among recipients of treatment with transfusion or hydroxyurea. Parvovirus B19 seroconversion was strongly associated with an increased risk of aplastic crisis in both SS (odds ratio of 29, 95% CI (11.3, 74.4)) and SC patients (odds ratio of 110, 95% CI (9.6, 1270.4)), even when controlling for age. Seroconversion was associated with an increased risk of acute chest syndrome in SC patients, (odds ratio of 6.4, 95% CI (1.9, 21.9)) but did not reach statistical significance in SS patients.These data show a clear causal relation between parvovirus B19 seroconversions and acute chest syndrome in subjects with hemoglobin SC disease and confirm the previously known association aplastic crisis.

Report of a collaborative study to calibrate the Second International Standard for parvovirus B19 antibody

A collaborative study was undertaken to assess the suitability of a replacement for the First International Standard for parvovirus B19 IgG, human serum and to calibrate it in IU. The proposed standard, which is a pool of sera from 16 US blood donors, was assayed along with the First International Standard, a coded duplicate of the proposed standard and a plasma sample from a single blood donor. Nine laboratories from eight countries participated in the studies and five different assay kits were used. Two kits contained VP1 + VP2, one kit contained VP1 only and two kits, one of which was used by five participants contained VP2 only. Differences in detection of the proposed standard and the individual plasma were observed with assay kits containing different antigens, VP1, VP2 or VP1 + VP2. However, since VP1 is a minor capsid protein and on its own does not assemble into virus like particles and the dominant response in individuals appears to be against VP2, it was considered reasonable to utilize only the data from kits containing VP2 antigen for the calibration of the proposed standard. The results of this study demonstrated that the proposed standard coded 01/602 was suitable to serve as the replacement International Standard for parvovirus B19, serum IgG, and this preparation was established as the Second International Standard for parvovirus B19 antibody, plasma human, with an assigned unitage of 77 IU per ampoule by the Expert Committee on Biological Standardisation of the World health Organisation in February 2003.

Differential Transmission of Parvovirus B19 in a Twin Gestation: A Case Report

Maternal infection with parvovirus B19 during pregnancy can cause aplastic anemia in the fetus. Severe anemia may lead to nonimmune hydrops or fetal demise. In the case reported, the demise of one twin was diagnosed by ultrasonography in an asymptomatic 21-year-old para 1-0-2-1 African American at the gestational age of 25 weeks. The deceased twin (A) was grossly hydropic with anasarca, ascites, pleural and pericardial effusions, and a thickened placenta. Parvovirus B19 DNA was found in the amniotic fluid of Twin A using the polymerase chain-reaction technique. Serial scans of Twin B showed normal growth and no evidence of hydrops. The pregnancy was managed expectantly until 29 weeks when delivery was indicated by maternal disseminated intravascular coagulation. Maternal IgM antiparvovirus B19 antibodies were detected at the time of delivery. Antiparvovirus B19 IgM antibodies were not present in Twin B. These serologic studies suggest a recent acute maternal infection and refute such an infection in Twin B. We present a case of differential transmission of parvovirus B19 in a twin pregnancy with in utero death of the infected twin and subsequent maternal disseminated intravascular coagulation.

Differential Transmission of Parvovirus B19 in a Twin Gestation: A Case Report

Maternal infection with parvovirus B19 during pregnancy can cause aplastic anemia in the fetus. Severe anemia may lead to nonimmune hydrops or fetal demise. In the case reported, the demise of one twin was diagnosed by ultrasonography in an asymptomatic 21-year-old para 1-0-2-1 African American at the gestational age of 25 weeks. The deceased twin (A) was grossly hydropic with anasarca, ascites, pleural and pericardial effusions, and a thickened placenta. Parvovirus B19 DNA was found in the amniotic fluid of Twin A using the polymerase chain-reaction technique. Serial scans of Twin B showed normal growth and no evidence of hydrops. The pregnancy was managed expectantly until 29 weeks when delivery was indicated by maternal disseminated intravascular coagulation. Maternal IgM antiparvovirus B19 antibodies were detected at the time of delivery. Antiparvovirus B19 IgM antibodies were not present in Twin B. These serologic studies suggest a recent acute maternal infection and refute such an infection in Twin B. We present a case of differential transmission of parvovirus B19 in a twin pregnancy with in utero death of the infected twin and subsequent maternal disseminated intravascular coagulation.

Human parvovirus B19 in young male patients with hemophilia A: associations with treatment product exposure and joint range-of-motion limitation.

To evaluate the risk of human parvovirus B19 (B19) transmission in recombinant antihemophilic factor, the seroprevalence among 798 two- to seven-year-old boys with hemophilia was compared. Also, data collected on joints were used to assess relations between B19 serostatus and joint range-of-motion (ROM) limitation. Staff at US hemophilia treatment centers collected data on product exposures and ROM of 10 joints and provided blood specimens as part of blood safety surveillance. Blood was tested for immunoglobulin G anti-B19. Associations between B19 seropositivity and treatment products and joint ROM limitations were examined in multivariate analyses. Compared to children who received no product, the odds of B19 seropositivity were 0.8 (p = 0.5), 1.9 (p = 0.05), and 7.6 (p < 0.001) for those children who received recombinant antihemophilic factor only, both recombinant antihemophilic factor and plasma-derived factor, and plasma-derived factor only, respectively. Children who were anti-B19 positive had an average 8 degrees less overall ROM (p = 0.002) than those who were B19 antibody negative after adjustment for other risk factors. The risk of B19 transmission by recombinant antihemophilic factor is low. Previous B19 infection is associated with ROM limitations in very young male patients with hemophilia. Virus inactivation techniques effective against B19 and other nonenveloped viruses are needed.

Circulating cytokines and chemokines in acute symptomatic parvovirus B19 infection: negative association between levels of pro-inflammatory cytokines and development of B19-associated arthritis.

The aim of the study was to characterise the profile and clinical correlates (arthritis, rash, and fatigue) of cytokines, chemokines, and other mediators in symptomatic acute parvovirus B19 infection. Serum was examined from cases of acute B19 infection (as defined by serum anti-B19 IgM positivity) (n = 84), and in normal persons (n = 43) for B19 markers (serum B19 antibodies and DNA), rheumatoid factor (RF), and antinuclear antibody (ANA). A panel of cytokines/chemokines was measured in duplicate using the Bioplex Protein Array system (BioRad Hemel Hempstead, UK). These included interleukin-1 beta (IL-1 beta), IL-4, IL-5, IL-6, IL-8, IL-13, tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), macrophage chemoattractant protein-1 (MCP-1), granulocyte-monocyte colony stimulating factor (GM-CSF), transforming growth factor-beta1 (TGF-beta 1), endothelin-1 (ET-1), and neopterin. Acute symptomatic infection was characterised by specific IgG positivity (83%), serum B19 DNA positivity (96%), and raised levels of IL-4, IL-6, IL-8, TNF-alpha, IFN-gamma, MCP-1, GM-CSF, TGF-beta 1, and ET-1. Patients with acute B19-associated arthritis were found to have lower levels of IL-6, TNF-alpha, and GM-CSF than patients without arthritis, while those with rash had lower levels of TGF-beta 1. It is concluded that cytokine levels following acute symptomatic infection with parvovirus B19 indicate a state of immune activation. The profile of circulating mediators may provide insights into the possible pathogenesis of particular clinical manifestations of this infection.

Development of a new 10% liquid, triple virus reduced intravenous immune globulin product, new generation IGIV

Rationale While immune globulin products after introduction of dedicated virus inactivation steps have an excellent safety record, patient concerns around transmission of particularly viruses still exist, and are fueled by newly emerging viruses. Methods To address these concerns, the manufacturing process of this new liquid IGIV contains three dedicated virus reduction steps: (1) a three component solvent-detergent (SD) treatment, (2) a 35 N nanofiltration step, and (3) a prolonged incubation period at low pH and elevated temperature. Results (1) SD treatment resulted in complete inactivation of all the lipid-enveloped viruses tested, already after only 1 minute of the 60 minutes treatment, and also at drastically reduced concentrations of the SD reagents. (2) Nanofiltration effectively removed lipid-enveloped viruses. Also, HAV and parvovirus B19, viruses which are smaller than the nominal pore size of the filter used, were reproducibly and robustly removed by antibody-enhanced nanofiltration which occurred at a wide range of HAV and B19 antibody concentrations. (3) Incubation at low pH and elevated temperature effectively inactivated lipid-enveloped viruses, and resulted in significant levels of inactivation for non-lipid enveloped viruses, including parvoviruses. Inactivation was shown to depend on a combination of low pH and elevated temperature. Conclusions The incorporation of three dedicated and mechanistically different virus reduction steps for this new liquid immunoglobulin product results in unprecedented safety margins.

Parvovirus B19 infection in medical students during a hospital outbreak.

From March to May 2002, a parvovirus B19 (B19) outbreak was identified at a general hospital that serves as a teaching facility for the Universidad Autónoma de San Luis Potosí, Mexico. Medical students attending the hospital presented with symptoms suggestive of B19 infection. Previous studies have suggested that apparent hospital-related B19 outbreaks may be a reflection of B19 infection in the community. A study was undertaken to assess whether exposure to the hospital was a risk factor for B19 infection and to determine to what extent medical students were infected during this outbreak. The incidence of B19 infection in medical students attending the teaching hospital during the outbreak (n=211) was determined and compared to students not attending the hospital (n=96). To assess if a community-wide outbreak had occurred, 80 blood donors were also evaluated for the presence of B19 antibodies. Acute B19 infection was identified in 40 of 119 (33.6%) susceptible students attending the hospital and in 20 of 47 (42.6%) susceptible students not attending the hospital. The frequency of acute infection among susceptible blood donors was lower (9.5%) than in students, but higher than the rate expected during non-epidemic periods. Most infections (68.3%) were asymptomatic. Symptoms reported by infected subjects were not specific for B19 infection. Only 11.7% of subjects with acute infection fulfilled the clinical surveillance definition used to detect cases during the outbreak. In conclusion, hospital exposure was not associated to increased risk of B19 infection among medical students. Medical students may be at increased risk for acquiring and transmitting B19 infection during outbreaks.