e86
LETTERS TO THE EDITORS
Human parvovirus 4 in Brazilian patients with haemophilia, beta-thalassaemia major and volunteer blood donors S. N. SLAVOV,* S. KASHIMA,*† M. C. ROCHA-JUNIOR,*† A. C. SILVA-PINTO,* € I N G E R ‡ and D . T . C O V A S * § L . C . O L I V E I R A , * A . M . E I S - H UB *Regional Blood Center of Ribeir~ ao Preto, Faculty of Medicine of Ribeir~ ao Preto, University of S~ ao Paulo; †Faculty of Pharmaceutical Sciences of Ribeir~ ao Preto, University of S~ ao Paulo, Ribeir~ ao Preto, S~ ao Paulo, Brazil; ‡Institute of Virology, University of Bonn Medical Centre, Bonn, Germany; and §Department of Clinical Medicine, Faculty of Medicine of Ribeir~ ao Preto, University of S~ ao Paulo, Ribeir~ ao Preto, S~ ao Paulo, Brazil
Human parvovirus 4 (PARV4, human partetravirus) was identified in 2005 in a plasma sample from a patient with symptoms suggestive of acute HIV infection, but who was HIV negative [for review see 1]. In general, PARV4 is believed to be transmitted through the parenteral route. This is supported by the increased PARV4 DNA prevalence in clotting factor concentrates and high anti-PARV4 antibody rates in patients with haemophilia and injection drug users (IDUs), but insignificant anti-PARV4 IgG prevalences in the general population [1–3]. On the contrary, in Sub-Saharan Africa and Asia, the general population demonstrates high antibody rates [4], suggestive of alternative transmission modes. PARV4 has been demonstrated in Europe, Africa, Asia and the USA [1], as yet, its occurrence in Brazil and South America is completely unknown. One hundred and thirty-six plasma samples were collected during November 2011–April 2012. Of them, 28 were derived from patients with haemophilia (92.9% haemophilia A, 7.1% haemophilia B, all severe haemophilia), all treated at the Regional Blood Center of Ribeir~ ao Preto, Medical Faculty of Ribeir~ ao Preto, University of S~ ao Paulo, Brazil. Additionally, 40 patients with beta-thalassaemia major and 68 volunteer blood donors were included in the study. All patients and donors signed a written informed consent. All haemophilic patients (mean age, 22 years, range, 12 months–54 years; all male) were treated with commercial coagulation factor and activated prothrombin complex concentrates. Of them, 14.3% (4/28) were reactive for anti-HCV IgG and 7.1% (2/28) for anti-HIV-1/2 IgG. The patients with beta-thalassaemia major (mean age, 22 years, range, 12 months-45 years; Correspondence: Svetoslav N. Slavov, PhD, Centro Regional de Hemoterapia do HCFMRP-USP, Rua Tenente Cat~ao Roxo 2501, 41051-140, Ribeir~ao Preto, S~ao Paulo, Brazil. Tel.: +551621019300 (ext 9680); fax: +551621019309; e-mail: [email protected] Accepted after revision 15 September 2014 DOI: 10.1111/hae.12564 Haemophilia (2015), 21, e70--e121
57.5% male) were receiving chronic transfusion therapy with red cell concentrates (3 units month1) obtained from Brazilian donors. The patients showed 27.5% (11/40) seroprevalence of anti-HCV IgG, and no seropositivity for anti-HIV-1/2 IgG. The volunteer blood donors (mean age, 35 years, range, 18–60 years; 69% males) did not report signs of acute infection prior to blood donation and were non-reactive for anti-HIV1/2, anti-HCV, anti-HBc, anti-HTLV-1/2, anti-Treponema pallidum and anti-Trypanosoma cruzi IgG. None of the tested individuals used intravenous drugs. DNA was extracted from 140 lL EDTA plasma using the QIAamp Viral RNA Mini Kit (QIAGEN, S~ ao Paulo, Brazil) according to the manufacturer’s instructions. PARV4 DNA amplification and quantification was performed in a reaction volume of 25 lL by realtime PCR (GoTaqâ qPCR Master Mix; Promega, Madison, WI, USA) using a previously described primer pair [5] targeting a highly conserved 103 bp fragment located in the viral ORF2. The cycling conditions were 50°C for 5 min, 95°C for 15 min, and 45 cycles each consisting of 15 s at 95°C and 1 min at 60°C followed by a melting curve obtained by slow heating between 60 and 95°C with increment 0.1°C s1 and fluorescence collection at 0.1°C intervals. All samples were tested in duplicates. The estimated sensitivity of the real-time PCR was 1 copy/reaction and was calculated using a decimally diluted plasmid-based standard obtained by cloning of the PCR target sequence from a known PARV4 DNA-positive sample (GenBank EU546206) ao into pCRâ 2.1-TOPO vector (Life Technologies, S~ Paulo, Brazil). Because of the low PARV4 load in the PCR-positive study samples, the amplicons were cloned in pCRâ 2.1-TOPO vector and sequenced using vectorspecific M13 primers. Precautions to prevent PCR contamination including separate laboratory rooms were strictly adhered to. Statistical analysis was performed using the SAS v.9 Software (SAS Institute Inc., Cary, NC, USA). Positive results were obtained from four plasma samples (n = 4/136, 2.9%, 95% CI: 0.8–7.4%) collected from one haemophilic infant, two patients with beta-thalassaemia major and one blood donor © 2014 John Wiley & Sons Ltd
© 2014 John Wiley & Sons Ltd
2200 1600 2400 Pos/Neg Neg/Neg Neg/Neg 37 18 Not available 27 20 Not available 178 9 103 287 9 103 Not available Beta-thalassaemia major Beta-thalassaemia major None Male Male Male 21 35 23 TL27 TL28 D8 (blood donor)
*Platelets range (normal): 150 9 103–450 9 103 cells per mm3. † Aspartate aminotransaminase (IU L1), range (normal): 8–40 IU L1 (males). ‡ Alanine aminotransaminase (IU L1), range (normal): 10–50 IU L1 (males). § Anti-HCV IgG/anti-HIV-1/2 IgG.
41 38 426 9 103 11.8
Activated prothrombin complex concentrate, solvent-detergent-treated FVIII, recombinant FVIIa Packed red cell concentrate Packed red cell concentrate None Haemophilia A Male 2 H6
e87
10.5 9.1 Not available
2000 Neg/Neg
HCV/HIV§ ALT‡ AST† Platelets* (per mm3) Haemoglobin (g dL1) Treatment Disease Gender Age (years) Patient no.
Table 1. Demographic and clinical characteristics of the PARV4 DNA-positive individuals.
(3.6%, CI: 0.09–18.4%; 5%, CI: 0.6–16.9%; and 1.5%, CI: 0.04–7.9% within each group). All blood samples were characterized by a low PARV4 load (Table 1). The nucleotide sequencing of the four PCR products revealed typical PARV4 genome sequences. All positive individuals were Caucasian males (Table 1). The haemophilic child suffered from haemophilia A and started the replacement therapy at 8 months of age. Until the detection of PARV4 the child had received a total of 5000 IU of plasma-derived solvent/ detergent-treated factor VIII concentrate, 11 500 IU of activated prothrombin complex concentrate and 3120 IU of recombinant factor VII. Clinically, the PARV4-positive patients and the blood donor showed normal haematological parameters and were asymptomatic. Their liver enzyme levels were in the normal range. In the patients with beta-thalassaemia major splenomegaly was absent. In this pioneer study examining the occurrence of PARV4 in Brazilian individuals receiving either blood products or donating blood, a PARV4 viraemia rate in the range of 2–5% was determined. Comparison of our results with the data obtained by others showed a similarity to the frequency of PARV4 viraemia documented in the USA (blood donors, 2%; HIV-negative IDUs and/or men who have sex with men, 6%) [5]. However, the prevalence in Brazil was lower compared to that observed in the Southern France (blood donors, 24%) [6], but was not as low as in the UK [4,7] and Germany [8] (0%). Detection of PARV4 in our patients requiring frequent transfusion of blood derivatives suggests that the infection might be acquired parenterally, similarly to the proposed transmission routes in the USA and Europe. In support of this, in one patient with betathalassaemia major, PARV4 infection was detected along with HCV infection, which is in agreement with other studies describing frequent PARV4 occurrence in individuals exposed to blood-borne viruses [1–3]. Unfortunately, the applied clotting factors and red cell concentrates were not available to prove or disprove transfusion-transmitted infection. Although, PARV4 DNA has been detected both in patients receiving haemotherapy [1,9] and in clotting factors and plasma pools [1,5], a direct link between PARV4 infection and administration of distinct blood derivative, as has been shown for parvovirus B19, has not been demonstrated so far. PARV4 viraemia was detected in a haemophilic infant of only 2 years of age. Provided that infection was transmitted by transfusion, this result indicates that the risk for acquiring PARV4 infection exists even after a relatively short period of haemotherapy. In a recent study following PARV4 uninfected haemophiliacs over a 5-year period, nine of them (8.2%) became infected resulting in an estimated annual PARV4
PARV4 viral load (copies per mL plasma)
LETTERS TO THE EDITORS
Haemophilia (2015), 21, e70--e121
e88
LETTERS TO THE EDITORS
incidence of 1.7% [9]. While we detected PARV4 in the absence of clinical symptoms (including normal haematological and liver parameters), in that study, rash, lymphadenopathy and hepatitis were observed during the acute phase of PARV4 infection. These symptoms, however, could not be clearly attributed to PARV4 because of concomitant HIV or HCV infection. Of note, very recent studies on the PARV4 resistance to physicochemical treatments revealed that PARV4 is more resistant to viral inactivation strategies applied during the manufacture of plasma derivatives than human parvovirus B19, a well-known contaminant of plasma pools [10]. On the contrary, the detection of PARV4 in a young blood donor (23 years of age) who donated blood for the first time, never received haemotherapy and denied drug abuse, suggests that the parenteral route might not be a unique way for PARV4 acquisition in Brazil. One limitation of our study is that the number of individuals tested was relatively small. Further studies, including a survey in the general population, are needed to precisely ascertain the PARV4 prevalence and transmission routes in Brazil. Moreover, our results were obtained in a transfusion centre distantly located from the state capital (S~ ao Paulo) and large metropolitan
References 1 Delwart E. Human parvovirus 4 in the blood supply and transmission by pooled plasma-derived clotting factors: does it matter? Transfusion 2012; 52: 1398–403. 2 Sharp CP, Lail A, Donfield S et al. High frequencies of exposure to the novel human parvovirus PARV4 in hemophiliacs and injecting drug users, as detected by a serological assay for PARV4 antibodies. J Infect Dis 2009; 200: 1119–25. 3 Lahtinen A, Kivel€a P, Hedman L et al. Serodiagnosis of primary infections with human parvovirus 4, Finland. Emerg Infect Dis 2011; 17: 79–82.
Haemophilia (2015), 21, e70--e121
areas. Therefore, they cannot be extrapolated, neither to the extensive territory of the country nor to South America but they add to the current understanding of the global prevalence of this emerging virus. Further evaluation of the PARV4 seroprevalence and genotype distribution in different South American countries is urgently needed to assess the PARV4 importance for the safety of blood products.
Acknowledgements The study was supported by the Fundacß~ao de Amparo e Pesquisa do Estado de S~ao Paulo-FAPESP, Brazil (grant no. 2009/16623-1, CTC-1998/ 14.247-6 and INCTC-2008/57.877-3), and the Conselho Nacional do Desenvolvimento Cientıfico e Tecnol ogico, Brazil (INCTC-573.754/2008-0). We are also grateful to Edson Zangiacomi Martinez for his help in statistical analysis.
Author contributions SNS gathered data and authored the manuscript. SK, MCRJ, ACSP, LCO, AMEH and DTC conducted the study and analysed the data.
Disclosures The authors stated that they had no interests which might be perceived as a posing conflict or bias.
4 Sharp CP, Vermeulen M, Nebie Y et al. Epidemiology of human parvovirus 4 infection in Sub-Saharan Africa. Emerg Infect Dis 2010; 16: 1605–7. 5 Fryer JF, Delwart E, Hecht FM et al. Frequent detection of the parvoviruses, PARV4 and PARV5, in plasma from blood donors and symptomatic individuals. Transfusion 2007; 47: 1054–61. 6 Touinssi M, Brisbarre N, Picard C et al. Parvovirus 4 in blood donors, France. Emerg Infect Dis 2010; 16: 165–6. 7 Maple PA, Beard S, Parry RP et al. Testing UK blood donors for exposure to human parvovirus 4 using a time-resolved fluorescence immunoassay to screen sera and
Western blot to confirm reactive samples. Transfusion 2013. 53: 2575–84. 8 Eis-H€ ubinger AM, Drexler JF, Reber U et al. Absence of detection of novel human parvoviruses in German plasma donations. Transfusion 2010; 50: 266–7. 9 Sharp CP, Lail A, Donfield S et al. Virologic and clinical features of primary infection with human parvovirus 4 in subjects with hemophilia: frequent transmission by virally inactivated clotting concentrates. Transfusion 2012; 52: 1482–9. 10 Baylis SA, Tuke PW, Miyagawa E et al. Studies on the inactivation of human parvovirus 4. Transfusion 2013. 53: 2585–92.
© 2014 John Wiley & Sons Ltd
Copyright of Haemophilia is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
LETTERS TO THE EDITORS
Human parvovirus 4 in Brazilian patients with haemophilia, beta-thalassaemia major and volunteer blood donors S. N. SLAVOV,* S. KASHIMA,*† M. C. ROCHA-JUNIOR,*† A. C. SILVA-PINTO,* € I N G E R ‡ and D . T . C O V A S * § L . C . O L I V E I R A , * A . M . E I S - H UB *Regional Blood Center of Ribeir~ ao Preto, Faculty of Medicine of Ribeir~ ao Preto, University of S~ ao Paulo; †Faculty of Pharmaceutical Sciences of Ribeir~ ao Preto, University of S~ ao Paulo, Ribeir~ ao Preto, S~ ao Paulo, Brazil; ‡Institute of Virology, University of Bonn Medical Centre, Bonn, Germany; and §Department of Clinical Medicine, Faculty of Medicine of Ribeir~ ao Preto, University of S~ ao Paulo, Ribeir~ ao Preto, S~ ao Paulo, Brazil
Human parvovirus 4 (PARV4, human partetravirus) was identified in 2005 in a plasma sample from a patient with symptoms suggestive of acute HIV infection, but who was HIV negative [for review see 1]. In general, PARV4 is believed to be transmitted through the parenteral route. This is supported by the increased PARV4 DNA prevalence in clotting factor concentrates and high anti-PARV4 antibody rates in patients with haemophilia and injection drug users (IDUs), but insignificant anti-PARV4 IgG prevalences in the general population [1–3]. On the contrary, in Sub-Saharan Africa and Asia, the general population demonstrates high antibody rates [4], suggestive of alternative transmission modes. PARV4 has been demonstrated in Europe, Africa, Asia and the USA [1], as yet, its occurrence in Brazil and South America is completely unknown. One hundred and thirty-six plasma samples were collected during November 2011–April 2012. Of them, 28 were derived from patients with haemophilia (92.9% haemophilia A, 7.1% haemophilia B, all severe haemophilia), all treated at the Regional Blood Center of Ribeir~ ao Preto, Medical Faculty of Ribeir~ ao Preto, University of S~ ao Paulo, Brazil. Additionally, 40 patients with beta-thalassaemia major and 68 volunteer blood donors were included in the study. All patients and donors signed a written informed consent. All haemophilic patients (mean age, 22 years, range, 12 months–54 years; all male) were treated with commercial coagulation factor and activated prothrombin complex concentrates. Of them, 14.3% (4/28) were reactive for anti-HCV IgG and 7.1% (2/28) for anti-HIV-1/2 IgG. The patients with beta-thalassaemia major (mean age, 22 years, range, 12 months-45 years; Correspondence: Svetoslav N. Slavov, PhD, Centro Regional de Hemoterapia do HCFMRP-USP, Rua Tenente Cat~ao Roxo 2501, 41051-140, Ribeir~ao Preto, S~ao Paulo, Brazil. Tel.: +551621019300 (ext 9680); fax: +551621019309; e-mail: [email protected] Accepted after revision 15 September 2014 DOI: 10.1111/hae.12564 Haemophilia (2015), 21, e70--e121
57.5% male) were receiving chronic transfusion therapy with red cell concentrates (3 units month1) obtained from Brazilian donors. The patients showed 27.5% (11/40) seroprevalence of anti-HCV IgG, and no seropositivity for anti-HIV-1/2 IgG. The volunteer blood donors (mean age, 35 years, range, 18–60 years; 69% males) did not report signs of acute infection prior to blood donation and were non-reactive for anti-HIV1/2, anti-HCV, anti-HBc, anti-HTLV-1/2, anti-Treponema pallidum and anti-Trypanosoma cruzi IgG. None of the tested individuals used intravenous drugs. DNA was extracted from 140 lL EDTA plasma using the QIAamp Viral RNA Mini Kit (QIAGEN, S~ ao Paulo, Brazil) according to the manufacturer’s instructions. PARV4 DNA amplification and quantification was performed in a reaction volume of 25 lL by realtime PCR (GoTaqâ qPCR Master Mix; Promega, Madison, WI, USA) using a previously described primer pair [5] targeting a highly conserved 103 bp fragment located in the viral ORF2. The cycling conditions were 50°C for 5 min, 95°C for 15 min, and 45 cycles each consisting of 15 s at 95°C and 1 min at 60°C followed by a melting curve obtained by slow heating between 60 and 95°C with increment 0.1°C s1 and fluorescence collection at 0.1°C intervals. All samples were tested in duplicates. The estimated sensitivity of the real-time PCR was 1 copy/reaction and was calculated using a decimally diluted plasmid-based standard obtained by cloning of the PCR target sequence from a known PARV4 DNA-positive sample (GenBank EU546206) ao into pCRâ 2.1-TOPO vector (Life Technologies, S~ Paulo, Brazil). Because of the low PARV4 load in the PCR-positive study samples, the amplicons were cloned in pCRâ 2.1-TOPO vector and sequenced using vectorspecific M13 primers. Precautions to prevent PCR contamination including separate laboratory rooms were strictly adhered to. Statistical analysis was performed using the SAS v.9 Software (SAS Institute Inc., Cary, NC, USA). Positive results were obtained from four plasma samples (n = 4/136, 2.9%, 95% CI: 0.8–7.4%) collected from one haemophilic infant, two patients with beta-thalassaemia major and one blood donor © 2014 John Wiley & Sons Ltd
© 2014 John Wiley & Sons Ltd
2200 1600 2400 Pos/Neg Neg/Neg Neg/Neg 37 18 Not available 27 20 Not available 178 9 103 287 9 103 Not available Beta-thalassaemia major Beta-thalassaemia major None Male Male Male 21 35 23 TL27 TL28 D8 (blood donor)
*Platelets range (normal): 150 9 103–450 9 103 cells per mm3. † Aspartate aminotransaminase (IU L1), range (normal): 8–40 IU L1 (males). ‡ Alanine aminotransaminase (IU L1), range (normal): 10–50 IU L1 (males). § Anti-HCV IgG/anti-HIV-1/2 IgG.
41 38 426 9 103 11.8
Activated prothrombin complex concentrate, solvent-detergent-treated FVIII, recombinant FVIIa Packed red cell concentrate Packed red cell concentrate None Haemophilia A Male 2 H6
e87
10.5 9.1 Not available
2000 Neg/Neg
HCV/HIV§ ALT‡ AST† Platelets* (per mm3) Haemoglobin (g dL1) Treatment Disease Gender Age (years) Patient no.
Table 1. Demographic and clinical characteristics of the PARV4 DNA-positive individuals.
(3.6%, CI: 0.09–18.4%; 5%, CI: 0.6–16.9%; and 1.5%, CI: 0.04–7.9% within each group). All blood samples were characterized by a low PARV4 load (Table 1). The nucleotide sequencing of the four PCR products revealed typical PARV4 genome sequences. All positive individuals were Caucasian males (Table 1). The haemophilic child suffered from haemophilia A and started the replacement therapy at 8 months of age. Until the detection of PARV4 the child had received a total of 5000 IU of plasma-derived solvent/ detergent-treated factor VIII concentrate, 11 500 IU of activated prothrombin complex concentrate and 3120 IU of recombinant factor VII. Clinically, the PARV4-positive patients and the blood donor showed normal haematological parameters and were asymptomatic. Their liver enzyme levels were in the normal range. In the patients with beta-thalassaemia major splenomegaly was absent. In this pioneer study examining the occurrence of PARV4 in Brazilian individuals receiving either blood products or donating blood, a PARV4 viraemia rate in the range of 2–5% was determined. Comparison of our results with the data obtained by others showed a similarity to the frequency of PARV4 viraemia documented in the USA (blood donors, 2%; HIV-negative IDUs and/or men who have sex with men, 6%) [5]. However, the prevalence in Brazil was lower compared to that observed in the Southern France (blood donors, 24%) [6], but was not as low as in the UK [4,7] and Germany [8] (0%). Detection of PARV4 in our patients requiring frequent transfusion of blood derivatives suggests that the infection might be acquired parenterally, similarly to the proposed transmission routes in the USA and Europe. In support of this, in one patient with betathalassaemia major, PARV4 infection was detected along with HCV infection, which is in agreement with other studies describing frequent PARV4 occurrence in individuals exposed to blood-borne viruses [1–3]. Unfortunately, the applied clotting factors and red cell concentrates were not available to prove or disprove transfusion-transmitted infection. Although, PARV4 DNA has been detected both in patients receiving haemotherapy [1,9] and in clotting factors and plasma pools [1,5], a direct link between PARV4 infection and administration of distinct blood derivative, as has been shown for parvovirus B19, has not been demonstrated so far. PARV4 viraemia was detected in a haemophilic infant of only 2 years of age. Provided that infection was transmitted by transfusion, this result indicates that the risk for acquiring PARV4 infection exists even after a relatively short period of haemotherapy. In a recent study following PARV4 uninfected haemophiliacs over a 5-year period, nine of them (8.2%) became infected resulting in an estimated annual PARV4
PARV4 viral load (copies per mL plasma)
LETTERS TO THE EDITORS
Haemophilia (2015), 21, e70--e121
e88
LETTERS TO THE EDITORS
incidence of 1.7% [9]. While we detected PARV4 in the absence of clinical symptoms (including normal haematological and liver parameters), in that study, rash, lymphadenopathy and hepatitis were observed during the acute phase of PARV4 infection. These symptoms, however, could not be clearly attributed to PARV4 because of concomitant HIV or HCV infection. Of note, very recent studies on the PARV4 resistance to physicochemical treatments revealed that PARV4 is more resistant to viral inactivation strategies applied during the manufacture of plasma derivatives than human parvovirus B19, a well-known contaminant of plasma pools [10]. On the contrary, the detection of PARV4 in a young blood donor (23 years of age) who donated blood for the first time, never received haemotherapy and denied drug abuse, suggests that the parenteral route might not be a unique way for PARV4 acquisition in Brazil. One limitation of our study is that the number of individuals tested was relatively small. Further studies, including a survey in the general population, are needed to precisely ascertain the PARV4 prevalence and transmission routes in Brazil. Moreover, our results were obtained in a transfusion centre distantly located from the state capital (S~ ao Paulo) and large metropolitan
References 1 Delwart E. Human parvovirus 4 in the blood supply and transmission by pooled plasma-derived clotting factors: does it matter? Transfusion 2012; 52: 1398–403. 2 Sharp CP, Lail A, Donfield S et al. High frequencies of exposure to the novel human parvovirus PARV4 in hemophiliacs and injecting drug users, as detected by a serological assay for PARV4 antibodies. J Infect Dis 2009; 200: 1119–25. 3 Lahtinen A, Kivel€a P, Hedman L et al. Serodiagnosis of primary infections with human parvovirus 4, Finland. Emerg Infect Dis 2011; 17: 79–82.
Haemophilia (2015), 21, e70--e121
areas. Therefore, they cannot be extrapolated, neither to the extensive territory of the country nor to South America but they add to the current understanding of the global prevalence of this emerging virus. Further evaluation of the PARV4 seroprevalence and genotype distribution in different South American countries is urgently needed to assess the PARV4 importance for the safety of blood products.
Acknowledgements The study was supported by the Fundacß~ao de Amparo e Pesquisa do Estado de S~ao Paulo-FAPESP, Brazil (grant no. 2009/16623-1, CTC-1998/ 14.247-6 and INCTC-2008/57.877-3), and the Conselho Nacional do Desenvolvimento Cientıfico e Tecnol ogico, Brazil (INCTC-573.754/2008-0). We are also grateful to Edson Zangiacomi Martinez for his help in statistical analysis.
Author contributions SNS gathered data and authored the manuscript. SK, MCRJ, ACSP, LCO, AMEH and DTC conducted the study and analysed the data.
Disclosures The authors stated that they had no interests which might be perceived as a posing conflict or bias.
4 Sharp CP, Vermeulen M, Nebie Y et al. Epidemiology of human parvovirus 4 infection in Sub-Saharan Africa. Emerg Infect Dis 2010; 16: 1605–7. 5 Fryer JF, Delwart E, Hecht FM et al. Frequent detection of the parvoviruses, PARV4 and PARV5, in plasma from blood donors and symptomatic individuals. Transfusion 2007; 47: 1054–61. 6 Touinssi M, Brisbarre N, Picard C et al. Parvovirus 4 in blood donors, France. Emerg Infect Dis 2010; 16: 165–6. 7 Maple PA, Beard S, Parry RP et al. Testing UK blood donors for exposure to human parvovirus 4 using a time-resolved fluorescence immunoassay to screen sera and
Western blot to confirm reactive samples. Transfusion 2013. 53: 2575–84. 8 Eis-H€ ubinger AM, Drexler JF, Reber U et al. Absence of detection of novel human parvoviruses in German plasma donations. Transfusion 2010; 50: 266–7. 9 Sharp CP, Lail A, Donfield S et al. Virologic and clinical features of primary infection with human parvovirus 4 in subjects with hemophilia: frequent transmission by virally inactivated clotting concentrates. Transfusion 2012; 52: 1482–9. 10 Baylis SA, Tuke PW, Miyagawa E et al. Studies on the inactivation of human parvovirus 4. Transfusion 2013. 53: 2585–92.
© 2014 John Wiley & Sons Ltd
Copyright of Haemophilia is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
