Parvovirus B19 outbreak in a children's ward

First report on severe septic shock associated with human Parvovirus B19 infection after cardiac surgery

Background

Human Parvovirus B19 (PB19) is a single-stranded DNA virus. Septic shock from viremia is rare with PB19; however, this infection can progress to life-threatening conditions. We report the first case of severe septic shock associated with a PB19 infection after cardiac surgery.

Case Presentation

A 50-year-old Chinese woman received elective double metal valve replacement, including the aortic valve and the mitral valve, under cardiopulmonary bypass (CPB) and suffered severe septic shock on postoperative day (PD) 30. Through the detection of PB19-specific nucleic acids in blister fluid and serum samples via metagenomic next-generation sequencing (mNGS), positive serum PB19 IgM and no other proven infection, acute PB19 infection was confirmed. After five days of combined treatment, no further fever or abdominal discomfort was noted, and the patient’s circulation gradually became stable without vasoactive medications.

Conclusion

PB19 may be an unrecognized cause of septic shock, rash, fever of unknown origin or multiple systemic signs and symptoms, especially in immunosuppressed and immunocompetent critically ill patients. Investigations for viral aetiology are needed.

Serological Markers of Viral Infections (Rubella Virus, Human Cytomegalovirus and Arboviruses) among Symptomatic Pregnant Women in Rural and Urban Areas of Mwanza, Tanzania

Viral infections have been associated with poor pregnancy outcomes. We investigated the magnitude of rubella virus (RV), dengue virus (DENV), Zika virus (ZIKV) and human cytomegalovirus (HCMV) among symptomatic pregnant women in rural and urban areas of Mwanza. A cross-sectional study was conducted between July 2017 and April 2018 in Mwanza. A rapid immunochromatographic test was done to detect ZIKV IgM and IgG as well as DENV IgM and IgG antibodies. A multiplex_RT-PCR was also done to detect the viral RNA genome. Enzyme immunoassays were done to detect RV and HCMV. Out of 171 participants, 1 (0.6%) was found to be seropositive for ZIKV_IgM antibodies, while 5 (2.9%) were ZIKV_IgG seropositive. DENV seropositivity was 9 (5.3%) and 3 (1.8%) for IgM and IgG, respectively, with all being PCR negative. Two participants (1.2%) were RV_IgM seropositive. 100% were HCMV_IgG seropositive and none was HCMV_IgM seropositive. Among 70 women with high HCMV_IgG titters, 10 (14.3%) had a low avidity index, indicating recent infections. Residing in rural areas (p = 0.044) and advanced age (p = 0.024) independently predicted ZIKV/DENV seropositivity. A substantial proportion of pregnant women had markers for viral infections. There is a need for introducing routine screening and monitoring pregnancy outcomes of positive cases to establish the relationship of these viruses and adverse pregnancy outcomes in endemic areas.

Oral fluid: Non-invasive alternative for parvovirus B19 diagnosis?

BACKGROUND

Infections with parvovirus B19 (B19V) have been associated with a wide range of disease manifestations of which erythema infectiosum (fifth disease) in children is most common. Clinical signs following infection of children with B19V can be similar to measles and rubella. Laboratory detection of B19V infections is based on detection of B19V-specific IgM antibodies by enzyme immunoassay (IgM-EIA) and/or B19V DNA by quantitative PCR (qPCR) on blood samples. The need for invasive sampling can be a barrier for public health diagnostics.

OBJECTIVES

To evaluate the use of a dual target B19V-qPCR directed against the NS1 and VP2 of B19V on oral fluid samples as a non-invasive alternative for laboratory diagnosis of B19V infections in children below 12 years of age with exanthema.

STUDY DESIGN

Oral fluid and serum samples were collected from 116 children with exanthema. All serum samples were tested by IgM-EIA/IgG-EIA, while all oral fluid and 56 serum samples were tested by B19V-qPCR.

RESULTS

B19V-specific IgM antibodies were detected in 25 of 116 children in the study. B19V DNA was detected in oral fluid in 17 of the 25 children who were IgM positive, as well as two children who were IgM-equivocal or negative. The child with the equivocal IgM had a high quantity of B19V DNA in oral fluid (7 log IU/ml), compatible with an acute B19V infection. The IgM-negative child was IgG-positive and 4 log IU/ml B19V DNA was detected in the oral fluid sample, suggesting an acute infection and a falsely negative IgM. Sample size calculations indicated that oral fluid samples for qPCR should be collected from 2 to 3 children during outbreaks of exanthema to achieve similar sensitivity as IgM-EIA for one child (≥0.9) to confirm or exclude B19V.

CONCLUSIONS

Results indicate that oral fluid samples are a suitable public health alternative for detection of B19V infections, potentially lowering the barriers for sampling.

Incidence and progression of Parvovirus B19 infection and molecular changes in circulating B19V strains in children with haematological malignancy: A follow up study

The present study was planned to estimate the incidence of human Parvovirus B19 infection and understand its progression in children suffering with hematological malignancy. The circulating B19V genotypes and viral mutations occurring in strains of B19V over one-year period were also studied. Children with malignancies were enrolled consecutively and were followed up for one-year period. Serum sample was collected at the time of enrolment and each follow up visit and was tested for anti B19V IgG and IgM as well as for B19V DNA. At least one B19V DNA positive sample from each patient was processed for sequencing. For patients positive for B19V DNA >1 time and at least 6 months apart, last positive sample from the same patient was also sequenced to study the nucleotide change over time. We have found very high incidence of B19V infection (100%) in the study population. All the patients tested positive for at least one B19V infection parameter (either antibodies or DNA) at least once, over one year of follow up. Cumulative percent positivity of anti B19V IgG, anti B19V IgM and B19V DNA was 85.3%, 45.2% and 72.1% respectively. Genotype 3b was reported, with occasional nucleotide change over one year period. DNA clearance was delayed in spite of appearance of IgG antibodies. Appearance of IgM class of antibodies was either delayed or absent. To conclude, children with haematological malignancies have high incidence of B19V infection with late and short lived serological response and persistence of DNA for long duration.

Human parvovirus B19 nosocomial outbreak in healthcare personnel in a paediatric ward at a national tertiary referral centre in Thailand

BACKGROUND

Nosocomial outbreaks of parvovirus B19 (pB19) have been reported, but they rarely occur among healthcare personnel (HCP). Susceptibility among pregnant HCP was the major concern.

METHODS

An outbreak of pB19 among HCP is described in a paediatric ward with a cross-sectional serologic study in all HCP and patients exposed to the outbreak. Acute infection was diagnosed by polymerase chain reaction or positive anti-parvovirus B19 IgM.

FINDINGS

Among 48 HCP (three pregnant) and 22 patients included in the outbreak serologic study, 11 (23%) HCP and two (9%) patients had acute infection. Of these, six HCP and no patients were symptomatic. Clinical manifestations included itchy rash (100%) and joint pain following resolution of rash (67%), with median rash duration of four days. Forty percent of HCP and 50% of patients had positive anti-parvovirus IgG, indicating previously immune status. HCP with acute infection and HCP who were susceptible without infection were younger than HCP with previous immunity (mean age 32.2 vs 40.5 years, respectively; P = 0.003). The attack rate was 38% among HCP and 18% among patients who were susceptible, respectively. The outbreak ended within two weeks following strict droplet precaution and segregation of symptomatic HCP.

CONCLUSION

Parvovirus B19 infection may cause nosocomial outbreak with high attack rate among HCP. Outbreak control with droplet precaution was highly effective.

Genotype 3b of human parvovirus B19 detected from hospitalized children with solid malignancies in a North Indian tertiary care hospital

Human parvovirus B19 (B19V) infection is known to cause serious consequences in immuno-compromized individuals. The present cross sectional study was designed to estimate the prevalence and genotype distribution of B19V in children receiving chemotherapy for solid malignancies at a tertiary care hospital in North India during October 2013 to May 2015. Serum samples from all the patients were tested for anti-B19V IgM and IgG antibodies and for B19V-DNA as soon as received. Samples testing positive for B19V-DNA were subjected to viral load estimation and to genotype determination by sequencing. Total 96 children were enrolled of which 9 (9.3%), 32 (33.3%), and 25 (26%) tested positive for anti-B19V IgM, anti-B19V IgG, and B19V-DNA, respectively. The viral load of B19V-DNA positive children ranged from 5.5 × 10(2) to 3.5 × 10(12) copies/ml. Accordingly children were divided into three groups: group I, with acute infection (n = 25); group II, previously exposed (n = 27), and group III, negative for B19V infection or with inappropriate antibody response (n = 44). B19V positivity was significantly associated (P-value < 0.0001) with a history of blood transfusion in the past 6 months, severe anemia (hemoglobin levels <6 gm%) and thrombocytopenia (platelets <150,000/cu.mm.). Sequence analysis of 21 of 25 DNA positive samples showed that all of them were Genotype 3b that clustered into three groups. All the sequences within each cluster were identical. The nucleotide identity of the sequences suggests a nosocomial outbreak of B19V during the study period. Children on chemotherapy for solid tumors should be routinely screened for B19V infection by both serology and PCR. J. Med. Virol. 88:1922-1929, 2016. © 2016 Wiley Periodicals, Inc.

Parvovirus B19

Primary parvovirus B19 infection is an infrequent, but serious and treatable, cause of chronic anemia in immunocompromised hosts. Many compromised hosts have preexisting antibody to B19 and are not at risk. However, upon primary infection, some patients may be able to mount a sufficient immune response to terminate active parvovirus B19 infection of erythroid precursors. The most common consequence of B19 infection in the compromised host is pure red-cell aplasia, resulting in chronic or recurrent anemia with reticulocytopenia. Anemia persists until neutralizing antibody is either produced by the host or passively administered. Parvovirus B19 should be suspected in compromised hosts with unexplained or severe anemia and reticulocytopenia, or when bone-marrow examination shows either giant pronormoblasts or absence of red-cell precursors. Diagnosis is established by detection of B19 DNA in serum in the absence of IgG antibody to B19. In some cases, IgG antibody is detected but is not neutralizing. Anti-B19 IgM may or may not be present. Therapy includes any or all of the following: red-cell transfusion, adjustment in medications to restore or improve the patient’s immune system, and administration of intravenous immunoglobulin (IVIG). Following treatment, patients should be closely monitored, especially if immunosuppression is unchanged or increased. Should hematocrit trend downward and parvovirus DNA trend upward, the therapeutic options above should be revisited. In a few instances, monthly maintenance IVIG may be indicated. Caregivers should be aware that B19 variants, though rarely encountered, can be missed or under-quantitated by some real-time polymerase-chain reaction methods.

Use of ward closure to control outbreaks among hospitalized patients in acute care settings: a systematic review

BACKGROUND

Though often used to control outbreaks, the efficacy of ward closure is unclear. This systematic review sought to identify studies defining and describing ward closure in outbreak control and to determine impact of ward closure as an intervention on outbreak containment.

METHODS

We searched these databases with no language restrictions: MEDLINE, 1946 to 7 July 2014; EMBASE, 1974 to 7 July 2014; CINAHL, 1937 to 8 July 2014; and Cochrane Database of Systematic Reviews, 2005 to May 2014. We also searched the following: IndMED; LILACS; reference lists from retrieved articles; conference proceedings; and websites of the CDCP, the ICID, and the WHO. We included studies of patients hospitalized in acute care facilities; used ward closure as a control measure; used other control measures; and discussed control of the outbreak(s) under investigation. A component approach was used to assess study quality.

RESULTS

We included 97 English and non-English observational studies. None included a controlled comparison between ward closure and other interventions. We found that ward closure was often used as part of a bundle of interventions but could not determine its direct impact separate from all the other interventions whether used in parallel or in sequence with other interventions. We also found no universal definition of ward closure which was widely accepted.

CONCLUSIONS

With no published controlled studies identified, ward closure for control of outbreaks remains an intervention that is not evidence based and healthcare personnel will need to continue to balance the competing risks associated with its use, taking into consideration the nature of the outbreak, the type of pathogen and its virulence, mode of transmission, and the setting in which it occurs. Our review has identified a major research gap in this area.

Seroprevalence of immunoglobulin G antibody to parvovirus B19 in Ontario

The prevalence of antibody to parvovirus B19 was assessed in two populations. In a group of 494 residents from Ontario and the Maritimes, virus-specific immunoglobulin (Ig) M antibody, a marker of acute infection, was found throughout the year but was most prevalent during the late winter and early spring months. The overall prevalence of IgG antibody in this group was 30.3%. In an effort to examine age-specific prevalence in this population, a second group of sera from 210 pediatric patients at The Hospital for Sick Children, Toronto, Ontario and from Red Cross blood donors was tested for the presence of B19-specific IgG, and of these, 31.4% of the samples were positive. This prevalence varied from 3.3% in the under five-year-old age group to 66.7% in the 35- to 45-year-old age group. Eighty per cent of sera from females of this group were seropositive. This study provides insight into the prevalence of parvovirus B19 IgG antibody in the population.

[Seroprevalence of antibodies against infectious pathogens relevant to pregnancy among healthcare workers]

Healthcare workers (HCWs) are exposed to infectious diseases throughout the course of their work. The concerns of pregnant HCWs are considerable because certain otherwise mild infections may affect fetal development. We studied 424 pregnant HCWs at the University Hospital Frankfurt between March 2007 and July 2011. Serological tests were carried out for varicella zoster virus (VZV), measles, mumps, rubella (MMR), cytomegalovirus (CMV) and parvovirus B19. Our overall seroprevalence data with regard to VZV, MMR, CMV and parvovirus B 19 corresponded to the general population. However, physicians demonstrated lower seroprevalence towards the two non-vaccine-preventable diseases (CMV: 37.5% [KI 27.4-48.5]; parvovirus B19: 69.3% [KI 58.6-78.7]) compared with nurses (CMV: 53.4% [KI 46.1-60.6], parvovirus B19: 75.1% [68.4-81.1]). It was striking that, only one in five of the study population showed IgG antibodies against all of the six pregnant-relevant viral diseases tested, of the physicians as few as one in six. A routine exclusion from the workplace due to non-immunity would mean that it would not be possible to employ the majority of pregnant staff in healthcare and childcare.

Cluster of parvovirus infection among hospital staff working in coronary care units

BACKGROUND

Parvovirus B19 is associated with erythema infectiosum in children or arthralgia and arthritis in adults. The virus is relatively conserved and nucleotide identity is expected in viruses that are epidemiologically related. Here, we describe the first cluster of parvovirus infection among hospital staff documented in Taiwan.

METHODS

Active surveillance was conducted in coronary care units (CCUs) at a 2200-bed teaching hospital for 1 month in 2007. A case defined clinically as occurring in a patient or staff in CCUs with new onset of fever or rash. Serum was tested for parvovirus B19 IgM and IgG by immunoblotting and DNA by nested polymerase chain reaction. When viremia was detected, nucleotide sequences were analyzed and compared with those of two clinical isolates. The attack rate was defined as the cumulative incidence of acute infection in CCU staff and patients during the study period.

RESULTS

Among 57 staff and 15 patients, five nurses met the clinical case definition. Three had acute infection as demonstrated by viral DNA and IgM. The attack rate was 5.3% for the staff and zero for patients. Seroprevalence rate was lower in staff than in patients (26.3%vs. 53.3%). The isolates collected from three cases were highly similar to a community isolate, and they varied with each other by 2-6 nucleotides. The isolate collected from a nurse was identical to that from her friend 3 weeks apart and was concordant with mutual transmission. A sequence with 45 nucleotide variations was identified from a staff member with chronic infection who was negative for IgM and had only weak IgG anti-VP1 reaction with immunoblotting. We did not find any patient as the source of infection.

CONCLUSION

We identified a cluster of parvovirus infection that was caused by three circulating strains which did not support the hypothesis of transmission of a single strain in CCUs.

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.

Parvovirus B19 infection in pediatric solid-organ and bone marrow transplantation

The clinical significance of parvovirus B19 infection in pediatric solid-organ and bone marrow transplanted patients is unclear. The overall prevalence of parvovirus B19 infection in these patients is about 1-2% during the first year after transplantation. The most common symptom is anemia, but leukopenia and thrombocytopenia have also been observed. Rare cases of hepatic dysfunction, myocarditis, vasculitis and respiratory failure have also been reported. Whereas serology is of limited value around the time of transplantation, it is recommended that a search for B19 DNA is included in first-line investigations in any transplanted patient with unexplained anemia. Specific antiviral therapy is not available, however, intravenous immunoglobulin produces rapid improvement in most cases. Although relatively rare, the severe complications following parvovirus B19 infection in the transplant setting can be avoided by early diagnosis and treatment.

Nosocomial spread of viral disease

Viruses are important causes of nosocomial infection, but the fact that hospital outbreaks often result from introduction(s) from community-based epidemics, together with the need to initiate specific laboratory testing, means that there are usually insufficient data to allow the monitoring of trends in incidences. The most important defenses against nosocomial transmission of viruses are detailed and continuing education of staff and strict adherence to infection control policies. Protocols must be available to assist in the management of patients with suspected or confirmed viral infection in the health care setting. In this review, we present details on general measures to prevent the spread of viral infection in hospitals and other health care environments. These include principles of accommodation of infected patients and approaches to good hygiene and patient management. They provide detail on individual viral diseases accompanied in each case with specific information on control of the infection and, where appropriate, details of preventive and therapeutic measures. The important areas of nosocomial infection due to blood-borne viruses have been extensively reviewed previously and are summarized here briefly, with citation of selected review articles. Human prion diseases, which present management problems very different from those of viral infection, are not included.

Nosocomial outbreak of parvovirus B19 infection in a renal transplant unit

BACKGROUND

Parvovirus B19 (B19) infection is known to cause chronic infection leading to anemia in immunocompromised patients. Although nosocomial B19 infections in immunocompetent patients have been documented, no outbreaks in immunocompromised patients have been previously reported. Whether transmission can occur from a patient with chronic infection is also unknown.

METHODS

An outbreak of B19 infection in a renal transplant unit was investigated by molecular analysis of the virus strains and a case-control study.

RESULTS

Three patients had genetically identical virus strains suggesting the occurrence of nosocomial transmission. The index case transmitted infection many weeks after the onset of her clinical symptoms. Other patients at risk of acquiring infection were those most intensively immunosuppressed. Viral load in the serum correlated with the hematological response. A rebound in the viral load was associated with clinical relapse and the failure of i.v. immunoglobulin therapy.

CONCLUSION

Nosocomial transmission of B19 can occur from immunocompromised patients even when they are in the chronic stage of the infection. The clinical and virological response to i.v. immunoglobulin therapy is variable and depends on the overall level of immunosuppression of the patient.

Infectious diseases

Approximately 5% of the general population develops a skin infection each year, leading to a significant number of outpatient visits to the primary care physician. Bacteria, infestations, fungi, yeasts, and viruses are organisms that present with a myriad of cutaneous findings that pose a challenge to the investigating clinician. This article provides a contemporary review of these skin infections, with particular emphasis on clinical features, and a concise, updated review on therapies.

A school outbreak of parvovirus B19 infection investigated using salivary antibody assays

An outbreak of parvovirus B19 infection at a primary school was investigated using saliva samples. Antibody capture immunoassays for salivary B19 IgG and IgM were developed using a recombinant B19 antigen and monoclonal antibody to B19 virus. Evaluation of the salivary IgG assay using paired serum and saliva samples from 43 staff at St Thomas' Hospital showed that it had a sensitivity of 100% and a specificity of 95%. Evaluation of the salivary B19 IgM assay using 87 paired blood and saliva samples from a study of general practitioner rubella notifications showed it had a sensitivity of 60% and a specificity of 98%. Using the salivary assay the level of B19 IgG within 2 weeks of the start of the outbreak ranged from 5-33% in children and 29% in staff. By detecting salivary B19 IgM and/or B19 IgG seroconversions, attack rates of 8-50% in children in different classes and 47% in staff were observed. Household transmission was also studied and an attack rate of 45% was recorded in 11 susceptibles. After the outbreak, the level of B19 IgG in children with the highest attack rates was 60-70%, similar to that seen in adults in the UK. This study highlights the risk of B19 infection in an institutional setting and shows that saliva samples are a useful alternative to blood.

Parvovirus B19 outbreak in a rehabilitation hospital

A nurse (index case) at a rehabilitation hospital was diagnosed with acute parvovirus B19 infection. A 2-year-old male patient was identified as the source patient. The epidemiological investigation focused on 15 individuals with symptomatic disease or risk factors for complications of parvovirus B19 infection. Serologic testing confirmed parvovirus B19 infection in the index case and source patient and identified a second health care worker who possibly contracted acute parvovirus B19 infection through nosocomial transmission. Parvovirus B19 infection can cause serious complications in pregnant women, persons with chronic hemolytic anemia, and persons with immunodeficiencies. Measures to control the transmission of parvovirus B19 infection should be part of the infection control plan at rehabilitation hospitals.

Parvovirus B19 infection

Human parvovirus B19, discovered in 1974, is a single-stranded DNA virus which causes erythema infectiosum, arthralgia, aplastic crisis in patients with red cell defects, chronic anaemia in immunocompromised patients, and fetal hydrops. Seroprevalence in developed countries is 2-10% in children less than 5 years, 40-60% in adults more than 20 years, and 85% or more in those over 70 years. The virus may be transmitted by the respiratory route and by transfusion of infected blood and blood products. After an incubation period of six to eight days, viraemia occurs, during which reticulocyte numbers fall dramatically resulting in a temporary drop in haemoglobin of 1 g/dl in a normal person. Clearance of viraemia is dependent on development of specific antibody to the B19 structural proteins, VP1 and VP2. The red cell receptor for the virus is blood group P antigen. Diagnosis in immunocompetent persons depends on detection of specific IgM in serum. Diagnosis in immunocompromised persons depends on detection of B19 antigen or DNA in serum. There is no specific treatment for B19 infection; however, human normal immunoglobulin may be used as a source of specific antibody in chronically infected persons. A recombinant parvovirus B19 vaccine is under development.

A synthetic parvovirus B19 capsid protein can replace viral antigen in antibody-capture enzyme immunoassays

To establish a renewable source of parvovirus B19 antigens for diagnostic tests, gene sequences for the viral capsid proteins, VP1 and VP2, were cloned into baculovirus expression vectors and the recombinant viruses used to infect Sf9 insect cells. Cell lysates examined by immunoblotting demonstrated reactive proteins corresponding to the expected sizes of native VP1 (83 kDa) and VP2 (58 kDa). The VP2 protein was produced efficiently in quantity and self-assembled into empty capsids as shown by density equilibration in a CsCl step gradient. The VP2 protein was purified and used as an antigen in antibody-capture enzyme immunoassays for the detection of B19 IgG and IgM antibodies. Compared to a standard antibody-capture EIA based on whole viral antigen, the VP2-EIA gave a sensitivity of 100% and specificity of 97% in detection of B19 IgM in 138 patients suspected of B19 infection. No IgM-positive specimens were missed. IgG detection yielded a sensitivity of 100% and specificity of 96% in the same population. Recombinant VP2 capsid proteins expressed in baculovirus-infected insect cells can substitute for serum-derived B19 virus in standard antibody-capture EIA for the detection of B19 IgG and IgM with comparable results.

Parvovirus B19 outbreak on an adult ward

In November and December 1992, an outbreak of parvovirus B19 infection occurred among patients and staff on an adult mixed surgical ward at a large hospital in London. Three patients and 15 staff members were serologically confirmed as acute cases. The attack rate among susceptible members of staff was 47%. In those infected, arthralgia (80%) and rash (67%) were the most common symptoms. Of six susceptible in-patients on the ward, three became infected. One of the in-patients who had carcinoma of the mouth was viraemic for more than 10 days with marrow suppression resulting in the postponement of chemotherapy until intravenous immunoglobulin was given and he was no longer viraemic. Control measures taken included closure of the ward to new admissions, transfer of only immune staff to the ward, and restriction of the ward nursing staff to working only on that ward. Although no specific exposure was conclusively identified as a risk factor, there was a suggestion of an increased risk of acquiring parvovirus B19 infection among those staff who did not adopt strict hand washing procedures after each physical contact with a patient (RR = 2.33; P = 0.07). Knowledge of parvovirus B19 among interviewed health care workers was poor: only 42% reported knowing about parvovirus B19 and only 38% could name a patient category at risk of a severe outcome following infection. This is the first report of a nosocomial outbreak affecting an adult ward and of possible transmission of parvovirus B19 infection from staff to in-patients. Hospital control of infection teams should include parvovirus B19 in their outbreak containment plans.

A recombinant immunoblot and ELISA for detection of acute parvovirus B19 infection

Laboratory diagnosis of parvovirus B19 (B19) infection has been hampered by the limited availability of B19 virus. Recombinant viral proteins are now available for use as antigen in serological assays. We compared detection of anti-B19 IgM by "mu-capture assay" using viral B19 particles to a recombinant (rec.) immunoblot and a rec. enzyme-immunoassay (ELISA) using viral structural proteins as antigens expressed in E. coli. The rec. immunoblot was 94.3% sensitive and 96.4% specific for anti-B19 IgM, and the sensitivity of the rec. ELISA was 94.3% and the specificity, only 72.7%. There was an agreement between the "mu-capture assay" and the rec. immunoblot in 87.8% and the rec. ELISA in only 74.4%. For detection of anti-B19 IgG in patients with acute B19 infection, the rec. immunoblot was 94.3% and the rec. ELISA 85.7% sensitive. The rec. immunoblot is more reliable for detection of acute B19 infection than the rec. ELISA.

Use of recombinant human parvovirus B19 antigens in serological assays

AIMS--To compare the sensitivity, specificity, and practicality of recombinant proteins in serological tests for the detection of human parvovirus B19 IgG and IgM. METHODS--Indirect enzyme linked immunosorbent assays using B19 structural proteins expressed in Escherichia coli were developed for the detection of B19 specific IgG and IgM (rELISA-G and rELISA-M). Cells infected with baculovirus expressing B19 structural proteins were also used in an indirect immunofluorescence assay for IgG and IgM antibodies (IFA-G and IFA-M). Antibody capture radioimmunoassays for IgG and IgM (GACRIA and MACRIA) were used as comparative assays. RESULTS--Twenty nine pools of intravenous immunoglobulin were clearly positive for B19 IgG by rELISA-G and contained low IgG titres by GACRIA. From 113 samples tested by all methods, sensitivities of 92% (77/84) and 97% (68/70) were obtained for ELISA and immunofluorescence, respectively, when compared with GACRIA. One hundred and sixteen samples from patients presenting with rash or arthralgia were compared by MACRIA, rELISA-M, and IFA-M. Sensitivities of both recombinant tests were more than 95%. Despite pretreatment to remove IgG or rheumatoid factor, false positive results were a problem in the rELISA-M but were not seen with the IFA-M. CONCLUSIONS--The limited supply of native antigen has severely restricted the wide application of serology for parvovirus B19. The use of recombinant antigens permitted the introduction of local screening tests which had many advantages, including quicker results and relief of the burden on the Reference Laboratory. The use of rELISA-M for sensitivity and IFA-M for specificity and confirmation proved a useful and practical combination for diagnosis of recent infection with B19, and rELISA-G allowed the immune response to be determined in selected populations.

Parvovirus B19 as a cause of chronic anemia in rhabdomyosarcoma

BACKGROUND

Several reports have been published of anemia due to infection by parvovirus in patients receiving chemotherapy for leukemia. However, parvovirus B19 has not been previously identified as a cause of chronic anemia in children with solid tumors.

METHODS

A child with rhabdomyosarcoma developed chronic anemia, with need for regular blood transfusions during chemotherapy. An infectious etiology was sought.

RESULTS

B19 viremia and an absent antibody response was present during the period of chronic anemia during chemotherapy. After completion of chemotherapy, the viremia cleared, IgM and IgG antibody to B19 virus were detected, and the anemia resolved.

CONCLUSIONS

Parvovirus must be considered as a cause of anemia in patients undergoing chemotherapy for solid tumors as well as leukemia.

Characterization of a nested polymerase chain reaction assay for detection of parvovirus B19

The characterization and application of a nested polymerase chain reaction (PCR) assay for the detection of human parvovirus B19 DNA is described. The assay was evaluated with 149 diagnostic serum samples (collected up to 150 days after the onset of symptoms) previously tested by dot blot hybridization for B19 DNA and by class-specific capture radioimmunoassays for the detection of B19 immunoglobulin M (IgM) and IgG. B19 DNA was detectable by the PCR in 70% of the sera. There was a statistically significant association between the detection of B19 DNA by PCR and high B19 IgM values (P < 0.005), low B19 IgG values (P < 0.05), and a short interval between onset of symptoms and serum collection (P < 0.005). Serial serum samples, throat swabs, and peripheral blood mononuclear cells collected from 10 individuals during an outbreak of parvovirus B19 were also tested by the nested PCR. B19 DNA was detectable in the throat swabs at the time of the clinical illness and in the peripheral blood mononuclear cell fraction up to the end point of the study 6 months after infection. The location of the B19 DNA could not be determined in cytocentrifuge preparations of peripheral blood mononuclear cells with nonisotopic in situ hybridization and immunolabelling.

Identification and use of a neutralising epitope of parvovirus B19 for the rapid detection of virus infection

A conserved neutralising epitope was confirmed as the site of specific activity for the monoclonal antibody R92F6. This monoclonal antibody was used to detect B19 viral antigen in serum samples after SDS-PAGE and Western blotting. Twenty samples from the United Kingdom, Ireland, Japan, and the United States were positive with this technique. Serum samples from various control groups were negative.