Transfusion Transmitted Infections in Armed Forces: Prevalence and Trends

Background

This study presents data on the prevalence rate of infectious markers among voluntary and replacement donors in the blood transfusion service in Armed Forces from 2000 to 2004.

Methods

39,646 units of blood were collected from donors during the period from 2000 to 2004. All the samples were screened for hepatitis B surface antigen (HBsAg), human immunodeficiency virus (HIV) 1&2, hepatitis C virus (HCV), and by venereal disease research laboratory test (VDRL).

Results

24,527 (61.9%) were voluntary donations and 15,119 (38.1%) replacement donations. Prevalence of HBsAg had decreased, amongst voluntary donors from 1.67% to 0.77% but the positivity rate has not showed significant change. Seropositivity of HIV had decreased both in voluntary and replacement donors to 0.22% and 0.86% respectively. The seropositivity for anti-HCV showed steady decrease amongst voluntary donors from 0.46% to 0.20% in 2004, but in replacement donors, there was an increase in reactivity rate from 0.43% to 0.65%.

Conclusion

The increased seropositivity for HCV, HIV and HBsAg could be decreased by introduction of nucleic acid amplification testing (NAT) in minipools for HCV and HIV and introduction of anti-HBcAg (IgM) for hepatitis B virus (HBV) infection. But this may not be possible in near future in developing countries due to financial constraints. At present implementation of strict donor criteria and with use of sensitive laboratory screening tests it is possible to reduce the incidence of transfusion transmitted infections (TTI) in Indian scenario.Key Words: Transfusion transmitted infections, Human immunodeficiency virus, Hepatitis C virus, Hepatitis B virus     

Infectious disease markers in blood donors

Background: The infectious disease markers for which blood donors are screened include anti-human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), anti-hepatitis C virus (HCV), rapid plasma reagin (RPR) card test for syphilis and malarial parasites.     

Socio-demographic characteristics associated with HIV and syphilis seroreactivity among pregnant women in Blantyre,Malawi, 2000–2004

Objectives

We aimed to evaluate socio-demographic factors associated with HIV and syphilis seroreactivity in pregnant Malawians presenting for antenatal care in late third trimester of pregnancy.

Methods

Between December 2000 and March 2004 at Queen Elizabeth Central Hospital Blantyre, Malawi, we collected cross-sectional clinical and socioeconomic data from consenting women. HIV-1 status was determined using rapid HIV antibody tests and syphilis seroreactivity was determined using Rapid Plasma Reagin (RPR) and confirmed with Treponema pallidum hemagglutination assay (TPHA).

Results

Of 3,824 women screened for HIV, 1156 (30%) were HIV seropositive and 198 (5%) were RPR and TPHA seroreactive. In the multivariate analysis, HIV infection was positively associated with elevated socio-economic status, being formerly married, and age, but not with education level. HIV prevalence was lower in women of Yao ethnicity than in other women (OR: 0.78, 95%CI: 0.64 – 0.95). Increased maternal education was negatively associated with syphilis seroreactivity.

Conclusions

The seroprevalence of HIV and syphilis among women attending the antenatal ward in Blantyre remains unacceptably high. Demographic correlates of HIV and syphilis infections were different. Our results demonstrate the need for better strategies to prevent HIV and syphilis in women and calls for optimizing antenatal syphilis screening and treatment in Malawi.     

The Role of anti-HBc IgM in Screening of Blood Donors

Background

Transfusion transmitted hepatitis B has always been a dreaded disease, with incidence of increased transmission through donated blood. The screening test for hepatitis B infection is detection of HBsAg that does not rule out the risk of transmission of hepatitis B as the donor may be in the ‘window period’. During this period, detection of the antibody to the hepatitis B core antigen (anti-HBc) IgM type serves as a useful serological marker. The aim of this study was to screen blood donors for anti-HBc type IgM and anti - HBc Ag total for detection and to find their incidence amongst blood donors.

Methods

2552 voluntary blood donors were screened by the ELISA method for HBsAg and anti - HBc IgM and other mandatory screening markers. 704 of the test blood samples were also screened for anti-HBc total.

Result

Of the 2552 donor, 47 (1.84 %) cases were HBsAg positive. A total of 11 (0.43 %) blood units were reactive for HBcAg IgM and of these, 10 (0.39 %) were HBsAg negative and reactive for anti-HBcAg IgM. Of the 704 samples tested for anti - HBcAg total, 112 (15.9%) samples were reactive.

Conclusion

Screening of blood for anti-HBc total is practical in the western world as the incidence of HBsAg and anti-HBc is low in these countries and these positive blood units for anti - HBcAg total can be discarded. This may not be practical in India as the incidence of anti- HBcAg total is high in our population. It is recommended that all blood units should be tested for anti - HBc IgM for infectivity status of the blood donors in the window period and to discard blood if positive.Key Words: Window period, Hepatitis B surface antigen, Anti hepatitis B core antigen     

Hepatitis C Virus Infection in Haemodialysis Patients: “Wolf in Sheep's Clothing”

Background

170 million people are infected with the Hepatitis C virus (HCV) around the world. Approximately 50%-70% patients infected with HCV develop chronic liver disease. Haemodialysis patients constitute an especially important group with high HCV prevalence. Outbreaks of HCV infection in dialysis units have been documented. Detection of anti-HCV antibodies is a convenient and conventional mode of documentation. However, in this group, it has it''s own caveats.

Methods

48 patients who had undergone or were on haemodialysis (HD) and had undergone a minimum of 15 dialysis sittings were studied. HCV infection was documented both by anti-HCV antibody detection and HCV RNA testing. A comparative evaluation of results by both tests was done.

Results

Out of a total of 48 patients, HCV RNA was detected in 38 (79.16%) and anti-HCV antibodies in 13(27.07%). Out of 48 patients 10(20.83%) were negative for both parameters. 22.91% (11/48) of patients were positive for both HCV RNA and anti-HCV antibody. 56.25% (27/48) were HCV RNA positive but anti-HCV antibodies were not detectable in their sera. 2 patients (04.16%) had a positive anti-HCV antibody status despite HCV RNA being negative. In 20.83% (10/48) both parameters were undetectable.

Conclusion

Chronic liver disease (CLD), particularly due to HCV infection, is a major complication amongst haemodialysis (HD) patients. Without reliable assays for antigenemia and the inability of antibody tests to define viremia in all cases, the detection of viral nucleic acid is necessary for diagnosis of active HCV infection.Key Words: Hepatitis C virus, Haemodialysis     

High prevalence of hepatitis C virus-ribonucleic acid positivity in anti-hepatitis C virus negative renal transplant patients

Background

Hepatitis C virus (HCV) infection is common in renal transplant (RT) patients. Some of these patients remain anti-HCV negative despite presence of infection and these are identified by a positive HCV-ribonucleic acid (RNA) test.

Methods

We studied 404 RT patients for prevalence of HCV-RNA positivity in anti-HCV negative patients. Serum was tested for presence of anti-HCV antibodies using a third generation HCV micro-ELISA (enzyme-linked immunosorbent assay) test, which utilises a combination of HCV structural and nonstructural antigens. The RNA was extracted from patient serum for HCV viral quantification using Quiagen Ql Amp Viral RNA mini extraction kit. The HCV-RNA viral load was performed on Corbet Rotor Gene 3000 thermocycler using Taqman principle.

Results

About 308 patients were anti-HCV negative and 96 were anti-HCV positive, resulting in prevalence of overt HCV infection of 23.7%. A total of 130 anti-HCV negative patients tested positive for HCV-RNA making a prevalence of occult HCV infection of 42.2%. There was no significant difference in the rate of overt or occult HCV infection between males and females. Patients with HCV infection (whether overt or occult) had received more number of dialysis sessions (62.5 vs 32.2) and blood transfusions (2.78 vs 1.99) when compared to those without HCV infection (P=0.001). The mean duration on dialysis was also longer (8.15 months vs 4.53 months) in patients with HCV infection (P= 0.0001).

Conclusion

A direct test for HCV viraemia is important to accurately determine the epidemiology of HCV infection in RT patients who remain anti-HCV negative despite harbouring active HCV infection.Key Words: hepatitis C, real time PCR, renal replacement therapy     

Prevalence of Human T Cell Leukaemia Virus amongst Blood Donors

Background

Human T cell leukaemia virus (HTLV) I/II are retroviruses implicated in transfusion transmitted infection. Present study was undertaken to assess seroprevalence of HTLV in voluntary blood donors along with pattern of blood utilisation. Methods: A total of 258 healthy blood donors who were free from infectious markers in transfusion as per current transfusion guidelines were enrolled. They were screened for HTLV-I/II antibodies by commercially available enzyme immuno assay (EIA) and their blood utilisation data was analysed.

Result

Five (1.9%) donors were found seropositive for HTLV-I/II of which 1.2 % were first time and 0.9% were repeat donors. Blood utilisation data revealed 20.9% and 38.8% units were utilised within 5 and 6–14 days of collection respectively. 45.9% recipients were transfused with single blood unit. 42.9% recipients were immunosuppressed due to underlying disease. Conclusion: The high prevalence of HTLV in blood donors, coupled with single unit transfusion, use of fresh blood, non availability of acellular blood products and immunosuppression in recipients can lead to significant transfusion transmitted HTLV infection. We suggest judicious use of blood products and screening of blood donors in prevention of transfusion transmitted HTLV-I/II.Key Words: HTLV-I/II, Blood donors; Transfusion transmitted infection; Retrovirus     

Serological Evidence of Chronic Chlamydia pneumoniae Infection in Coronary Artery Disease

Background

Recent studies have suggested that Chlamydia pneumoniae infection could be involved in atherosclerosis and related clinical manifestations such as coronary artery disease, carotid artery stenosis and myocardial infarction.

Methods

Serum IgG, IgM and IgA antibodies to chlamydia genus specific antigen were measured by enzyme linked immunosorbent assay (ELISA) in 100 cases of angiographically demonstrated coronary artery disease (CAD) and 100 randomly selected healthy individuals as controls after matching for age and sex. All the samples positive for chlamydia genus specific IgG antibodies were then subjected to Chlamydia pneumoniae species specific IgG antibody ELISA.

Results

Seroprevalence of chlamydia genus specific IgG antibodies in control group was 59% with an increase in seropositivity with increasing age. The overall seroprevalence of IgG antibodies was 76% in CAD group and the prevalence was significantly high in all age groups as compared to controls. The odds ratio was 2.20 for seropositivity of chlamydia genus specific IgG antibodies in patients with myocardial infarction (MI) and/or angina than in control group. No significant association was observed for IgA and IgM anti-chlamydial antibodies. The odds ratio for prevalence of Chlamydia pneumoniae species specific IgG antibodies in CAD patients increased to 2.55 in comparison to age and sex matched controls.

Conclusion

Current study supports the reported association between C pneumoniae infection and CAD in Indian population.Key Words: Chlamydia pneumoniae, Coronary artery disease     

Prevalence of HIV seropositivity among patients with squamous cell carcinoma of the conjunctiva

Objective

To determine the prevalence of HIV seropositivity among patients with squamous cell carcinoma of the conjunctiva.

Methods

All patients with clinical and histopathological confirmation of squamous cell carcinoma seen during a ten year period (July 1999 to June 2009) were tested for HIV (Human Immunodeficiency Virus). The number of patients with squamous cell carcinoma of the conjunctiva who are HIV positive were counted.

Results

A total of thirty-three(33) eyes in thirty-two(32) patients were confirmed histopathologically to have conjunctival squamous cell carcinoma. Their ages ranged from 22 years to 66 years with a mean age of (38.6±11.8) years (SD). The male to female ratio was 1:1.5. Twenty four (75%) of these patients were HIV positive.

Conclusions

Squamous cell carcinoma is associated with the human immunodeficiency virus and is thus a marker for the disease in Benin City, Nigeria.     

Prevalence of malaria infection in Sarbaz,Sistan and Bluchistan province

Objective

To survey malaria prevalence in Sarbaz from April 2009 to October 2010.

Methods

Epidemiological data of 1 464 confirmed malarial patients were analyzed according to demographic status, sex, age, nationality, isolated species and residence place.

Results

The majority of patients were male 950 (64.8%) but 514 (35.2%) were female. 82.5% of patients were Iranian, 14% Pakistani immigrants, and 3.5% Afghan immigrants. Data collected showed that 90% of isolated species were Plasmodium vivax, 7.8% Plasmodium falciparum, and 2.2% Plasmodium malariae and mixed species.

Conclusions

Therefore, it is crystal clear that refugees should be prohibited by government and controlled by experts in health centers in order to campaign effectively with this life threating disease.     

Evaluation of a new chemiluminescence immunoassay for diagnosis of syphilis

Objective

To assess the sensitivity, specificity, and feasibility of a new chemiluminescence immunoassay (CLIA) in the diagnosis of syphilis.

Methods

At first, a retrospective study was conducted, using 135 documented cases of syphilis and 30 potentially interfering samples and 80 normal sera. A prospective study was also performed by testing 2, 071 unselected samples for routine screening for syphilis. CLIA was compared with a nontreponemal test (TRUST) and a treponemal test (TPPA).

Results

There was an agreement of 100% between CLIA and TPPA in the respective study. The percentage of agreement among the 245 sera tested was 100.0%. Compared with TPPA, the specificity of CLIA was 99.9% (1817/1819), the sensitivity of CLIA was 100.0% (244/244) in the prospective study. CLIA showed 99.5% agreement with TPPA by testing 2, 071 unselected samples. And CLIA seemed to be more sensitive than TPPA in detecting the samples of primary syphilis.

Conclusions

CLIA is easy to perform and the indicator results are objective and unequivocal. It may be suitable for large-scale screening as a treponemal test substituted for TPPA.     

Seroprevalence of Cytomegalovirus among Voluntary Blood Donors

Background

Primary cytomegalovirus (CMV) infection in immunocompetent host is self limiting infection, leading to latency of virus. However congenital CMV and CMV infections in immunocompromised patients are associated with high morbidity and mortality. Transfusion transmitted-cytomegalovirus (TT-CMV) infection in low birth weight neonate and immunocompromised transfusion recipients is being increasingly reported. Studies recommended transfusion of CMV free or CMV safe blood in prevention of TT-CMV. In this background, the study was undertaken to assess the CMV seroprevalence in blood donor.

Methods

A prospective study was conducted in which 431 voluntary blood donors were screened for CMV IgG and IgM by EIA (Enzyme Immuno Assay).

Result

A total of 379 (87.9 %) voluntary blood donors were seropositive for CMV IgG. There was no statistical difference of CMV seropositivity and age. Further, seven (1.6%) subjects were both CMV IgM and IgG seropositive.

Conclusion

High seroprevalence of CMV in our donor population is a threat to the blood safety. Strategies in reducing the risk of TT- CMV are discussed. Use of prestorage leucodepleted ‘CMV safe’ blood components along with judicious use of blood is recommended in prevention of TT-CMV in high risk recipients.Key Words: Cytomegalovirus, Transfusion transmitted infections, Blood donors, Leucodepletion     

Hepatitis B e Antigen Negative Chronic Hepatitis in Indian Patients : A Reality

Background

Hepatitis B e antigen negative chronic hepatitis (e⁻ CHB) with detectable levels of hepatitis B virus DNA (HBV DNA) in serum has been reported in cases from Asia. This study was undertaken to find out prevalence e⁻CHB and to correlate its presence with the clinical status and severity of the illness in cases of chronic liver disease in India.

Methods

All patients of infective hepatitis, who were hepatitis B surface antigen (HBsAg) positive by enzyme-linked immunosorbent assay (ELISA), were evaluated with liver function tests and HBeAg and antiHBe antibody studies. Polymerase chain reaction (PCR) test was carried out to detect HBV DNA qualitatively.

Result

Out of 2064 samples tested by ELISA, 429 (20.78 %) were HBsAg positive. HBV DNA (qualitative) was performed on all 429 patients and 74 (17.2%) were HBV DNA positive. Of these only 42 (56.75 %) tested positive for HBeAg. Overall, 8.3 % of HBeAg negative patients (32/384) were viraemic with evidence of chronic liver disease/clinical cirrhosis and alteration of transaminase levels, while three cases (0.84 %) HBeAg positive cases did not show presence of HBV DNA.

Conclusion

This study shows e⁻CHB prevalence rate of 8.3% in patients with HBV infection in India. Since HBeAg negative patients had detectable levels of HBV DNA as seen in HBeAg positive patients, benefit of antiviral therapy should be given to them. Population studies on e⁻ CHB cases are needed to determine its true prevalence, natural course and response to therapy.Key Words: Chronic hepatitis, Hepatitis B virus, Hepatitis B e antigen negative     

Prevalence of occult hepatitis B amongst Indian human immunodeficiency virus type 1 infected individuals—a pilot study

Background

The diagnosis of hepatitis B is routinely based on the detection of hepatitis B surface antigen (HBsAg) only. However, occult hepatitis B virus (HBV) infection (OBI), which is defined as infection with positive hepatitis B core antibody (anti-HBc) antibodies, positive DNA (deoxyribonucleic acid) PCR (polymerase chain reaction), and undetectable HBsAg, as well as anti-HBs antibodies in serum or plasma of HBV infected individuals, will remain undetected using this screening diagnostic approach of detecting HBsAg. The current study aims in studying the prevalence of the OBI amongst human immunodeficiency virus type 1 (HIV-1) infected individuals who have not been exposed to anti-retroviral therapy.

Method

Estimation of HBsAg, anti-HBs, and anti-HBc total antibody status amongst 100 HIV-1 infected study participants was carried out using enzyme-linked immunosorbent assay (ELISA) kits. Detection of HBV-DNA was carried out by in-house qualitative PCR. CD4 + T lymphocyte counts were analysed using Becton Dickinson''s (BD) FACSCount™ system.

Results

The median age of the HIV-1 infected study population was 35 years (range: 22–67), with the gender distribution being 53 males and 47 females. The mean CD4 T lymphocyte count of the study participants was 210/mm³. Overall, serological evidence of HBV infection was observed in 28% of the HIV-1 infected study participants. There was 5% seropositivity for HBsAg, of which 2% were additionally positive for HBV-DNA-PCR. “Anti-HBc alone” status was seen in 18% of study participants, this being statistically higher in those with CD4 T lymphocyte counts < 200/mm³. While there was a single specimen with co-positivity for anti-HBc total antibodies and HBV-DNA, 5% of the in the study population exhibited anti-HBs antibodies positivity, with one sample exhibiting dual positivity for HBsAg and anti-HBs antibodies.

Conclusion

Occult HBV infections may contribute to chronic liver damage, and associ-ated reactivation amongst immunocompromised individuals, HIV-1 in-fected being a subset of them. “Anti-HBc” testing followed by HBV-DNA detection by PCR can be utilised for such populations to detect OBIs. Early detection of hepatitis B viraemia will be important for deciding the antiviral therapeutic protocol so as to avoid evolution of antiviral resistance in the circulating HBV strains in HIV-1 infected individuals harbouring OBIs.Key Words: human immunodeficiency virus, occult hepatitis B     

Rank-based spatial clustering: an algorithm for rapid outbreak detection

Objective

Public health surveillance requires outbreak detection algorithms with computational efficiency sufficient to handle the increasing volume of disease surveillance data. In response to this need, the authors propose a spatial clustering algorithm, rank-based spatial clustering (RSC), that detects rapidly infectious but non-contagious disease outbreaks.

Design

The authors compared the outbreak-detection performance of RSC with that of three well established algorithms—the wavelet anomaly detector (WAD), the spatial scan statistic (KSS), and the Bayesian spatial scan statistic (BSS)—using real disease surveillance data on to which they superimposed simulated disease outbreaks.

Measurements

The following outbreak-detection performance metrics were measured: receiver operating characteristic curve, activity monitoring operating curve curve, cluster positive predictive value, cluster sensitivity, and algorithm run time.

Results

RSC was computationally efficient. It outperformed the other two spatial algorithms in terms of detection timeliness, and outbreak localization. RSC also had overall better timeliness than the time-series algorithm WAD at low false alarm rates.

Conclusion

RSC is an ideal algorithm for analyzing large datasets when the application of other spatial algorithms is not practical. It also allows timely investigation for public health practitioners by providing early detection and well-localized outbreak clusters.     

1992～2000年血友病甲患者HCV、HBV、HIV和梅毒感染情况调查分析

目的:了解血友病甲患者丙型肝炎病毒(HCV)、乙型肝炎病毒(HBV)、艾滋病病毒(HIV)及梅毒的感染情况。方法:对1992年～2000年山东省血液中心确诊和治疗的162例血友病甲患者进行了抗-HCV、HBsAg、丙氨酸氨基转移酶(ALT)、抗-HIV和梅毒抗体血清学检测,并随机选择1000例无偿献血者作为正常对照。结果:162例血友病甲患者抗-HCV、HBsAg和ALT阳性率分别为20.73％(33/162)、4.32％(7/162)和8.64％(14/162);无偿献血者抗-HCV、HBsAg阳性率和ALT异常率分别为3.00％(30/10000)、10.00％(100/1000)和2.00％(20/1000);血友病甲患者和无偿献血者抗-HIV和梅毒抗体阳性率均为0。结论:血友病甲患者抗-HCV阳性率和ALT异常率高于无偿献血者(x~2 分别为 82.04和21.65,P <0.05),BHsAg阳性率低于无偿献血者(x~2=6.72,P <0.05),血友病甲患者和无偿献血者均无HIV和梅毒阳性反应。     

HIV, HCV, and HBV co-infections in a rural area of Shanxi province with a history of commercial blood donation

Background:Unhygienic blood collection in the early 1990s led to blood‐borne infections in Central China.This study aimed to estimate human immunodeficiency virus (HIV) co‐infection with hepatitis C and B viruses (HCV and HBV) and their risk factors in a rural area of Shanxi Province with a history of commercial blood donation.Methods:A cross‐sectional study was conducted in 2004.All adult residents in the target area were invited to participate in the study.Face‐to‐face interviews were completed and blood ...     

Prevalence of Helicobacter pylori,cytomegalovirus, and Chlamydia pneumoniae immunoglobulin seropositivity in coronary artery disease patients and normal individuals in North Indian population

Background

In present day atherosclerosis is perceived as a chronic inflammatory vascular condition and infectious diseases are believed to contribute to its pathophysiology. In this context, the microorganisms which are believed to play a role in the pathophysiology include Chlamydia pneumoniae, cytomegalovirus (CMV), and Helicobacter pylori.

Method

A case control study (retrospective) was conducted over a two-year period. The study population was divided into two groups with 200 individuals in each group. The first group comprised cases of coronary artery disease (CAD) and the second comprised healthy controls selected from the general population after matching for age and sex. Enzyme-linked immunosorbent assay (ELISA) was done for immunoglobulin (IgG) antibodies to H. pylori, C. pneumonia, and CMV. They were also evaluated for conventional risk factors including hypertension, diabetes, obesity, and dyslipidaemia. Epi Info™ version 6 six software was used for analysis of data. Odds ratio, χ² for trend and multiple logistic regression analysis were used to find out statistically significant results.

Results

Seropositivity for H. pylori was present in 119 patients of CAD (59.5%) but it was present in only 76 controls (38%) (P = 0.001). There was a statistically significant association between seropositivity for H. pylori and CAD. There was no statistically significant association between C. pneumoniae and CMV seropositivity with CAD. Multiple logistic regression analysis was done with CAD as the outcome (dependent variable). The predictor covariates (independent) variables were seropositivity to H. pylori, C. pneumoniae, and CMV, hypertension, obesity, diabetes, and dyslipidaemia. It was found that seropositivity to H. pylori, hypertension, obesity, and dyslipidaemia were significant risk factors for CAD.

Conclusion

Our study shows an association between IgG antibody response to H. pylori and CAD. Multiple logistic regression analysis showed that this association was retained even on comparison with the other risk factors.Key Words: Chlamydia pneumoniae, coronary artery disease, cytomegalovirus, Helicobacter pylori     

Seroprevalence of human parvovirus B19 in healthy blood donors

Background

Human parvovirus B19 is an emerging transfusion transmitted infection. Although parvovirus B19 infection is connected with severe complications in some recipients, donor screening is not yet mandatory. To reduce the risk of contamination, plasma-pool screening and exclusion of highly viraemic donations are recommended. In this study the prevalence of parvovirus B19 in healthy blood donors was detected by ELISA.

Methods

A total of 1633 samples were screened for IgM and IgG antibodies against parvovirus B19 by ELISA. The initial 540 samples were screened for both IgM and IgG class antibodies and remaining 1093 samples were screened for only IgM class antibodies by ELISA.

Results

Net prevalence of IgM antibodies to human parvovirus B19 in our study was 7.53% and prevalence of IgG antibodies was 27.96%. Dual positivity (IgG and IgM) was 2.40%.

Conclusion

The seroprevalence of human parvovirus B19 among blood donor population in our study is high, and poses an adverse transfusion risk especially in high-risk group of patients who have no detectable antibodies to B19. Studies with large sample size are needed to validate these results.