Human Brucellosis: Risks and Prevalence among Iranian Blood Donors Residing in Endemic Areas.

BACKGROUND: Brucellosis is a common zoonotic infection worldwide. Transmission can be occasionally observed via transfusion or transplantation. This study was designed to survey the seroprevalence of anti-Brucella antibody in blood donors in different endemic provinces. MATERIALS AND METHODS: A total of 14,706 blood donors from the 5 most prevalent provinces were studied by standard tube agglutination (STA) and any positive subjects were further confirmed by 2-mercaptoethanol agglutination test (2-ME). Significant titres were 80 for STA and 40 for 2-ME. RESULT: A total of 63 (0.43%) serum samples were STA-positive. Of these, the 2-ME test was reactive in 42 samples. The 2-ME test was reactive in 31 samples with a low titre. However, concomitant STA ≥80 and the titre of ≥40 for the 2-ME test were found in 11 subjects (0.075%), mostly resident in urban areas. Exposure to manure products was identified as a significant risk factor (p = 0.0128). Conclusion : The observed data show a somewhat noticeable prevalence among Iranian blood donors, bringing attention to the importance of pre-donation screening via a questionnaire which supplies answers about occupational history, and any history of exposure or past infections. Further studies to evaluate the frequency and related risk factors in certain populations, in conjunction with implementing stricter regulations in blood donor selection in endemic areas, may be necessary.

Human parvovirus B19 in patients with beta thalassemia major from Tehran, Iran.

BACKGROUND: Due to the tropism of human parvovirus B19 to erythroid progenitor cells, infection in patients with an underlying hemolytic disorder such as beta-thalassemia major leads to suppression of erythrocyte formation, referred to as transient aplasia crisis (TAC), which may be life-threatening. We investigated the prevalence of parvovirus B19 among patients with beta thalassemia major attending the Zafar Adult Thalassemia Clinic in Tehran, Iran. METHODS: This cross-sectional study was performed to determine the presence of parvovirus B19 DNA in blood samples and parvovirus B19 genotypes in plasma samples of patients with thalassemia major. The population consisted of 150 patients with beta-thalassemia major who attended the Zafar clinic in Tehran. Specimens were studied using a real-time polymerase chain reaction assay. RESULTS: The prevalence of parvovirus B19 in our study population was 4%. Of 150 patients with thalassemia, six (4%) were positive for B19 DNA. There was no significant correlation between blood transfusion frequency and B19 DNA positivity. Finally, phylogenetic analysis of human parvovirus B19 revealed genotype I in these six patients. CONCLUSION: In this study, acute B19 infections were detected in patients with beta thalassemia major. Screening of such high-risk groups can considerably reduce the incidence and prevalence of B19 infection; thus, screening is required for epidemiologic surveillance and disease-prevention measures.

Trends in Sero-Epidemiology of Human Immunodeficiency Virus in Voluntary Blood Donations in Iran, 2008-2013.

BACKGROUND: Various strategies are implemented to increase blood safety. However, there is always a small amount of residual risk. The amount of risk is associated with the incidence and prevalence of infection in the community. Since increases in the prevalence and changing the pattern of HIV transmission have been observed in the community, monitoring of HIV prevalence among general population and blood donors is necessary. This study aimed to determine the prevalence of HIV in Iranian blood donations. Demographic status and donation type were also investigated in HIV positive blood donors. METHODS: In the time frame of this study (2008 - 2013), the records of 11,504,231 donations were analyzed and all relevant data were extracted from the central database of the Iranian Blood Transfusion Organization. Demographic characteristics and type of donations were investigated. Descriptive and analytical statistics were used to summarize the obtained data. RESULTS: A total of 421 blood donations were HIV sero-positive. Trends in HIV prevalence from 2008 to 2013 per 100000 donations were found as follows: 3.8, 4.3, 3.8, 3.8, 3, and 2.9, respectively. The average prevalence was 3.6 per 100000. The prevalence rate showed a fluctuation from 3.8 to 2.9 per 100000. Gradual reduction has occurred in HIV sero-prevalence but the difference is not statistically significant. The risk of HIV sero-positivity was higher in single and female blood donors. The prevalence of HIV was much higher among donations from first-time than from regular and lapsed donors. CONCLUSIONS: The low prevalence rate of HIV in Iranian blood donations suggests the effectiveness of current safety strategies. However, implementing new strategies or improving the existing ones are advisable.

Seroprevalence and geographical distribution of human T-lymphotropic virus type 1 among volunteer blood donors in endemic areas of Iran.

BACKGROUND: Human T-cell lymphotrophic virus type 1 (HTLV-1) has a worldwide distribution and it is endemic in some regions of Iran. One of the most important routes of HTLV-1 transmission is via transfusion of contaminated blood components. The risk of transmission through asymptomatic blood donors, particularly in endemic areas should be considered and appropriately managed. The main objective of this study was to determine the seroprevalence and description the geographic distribution of HTLV-1 among voluntary blood donors in Iran. METHODS: This retrospective study carried out using the data obtained from the main database of the seven blood transfusion centers of Iranian Blood Transfusion Organization between 2009 and 2013. The presence of anti-HTLV-1/2 antibodies were primarily assessed using Enzyme-linked Immunosorbent Assay. The Ab Kit assay, contain antigens for the screening of antibodies to HTLV type 1 and 2. So, it is expressed as HTLV 1/2 assay. Samples that were positive by the western blot confirmatory test were considered as definite positive HTLV-1 or HTLV-2 cases. The main socio-demographic variables were; age, gender, donation history and marital status. Descriptive and analytical statistics were used to summarize the gathered data. The chi-Square Statistical test was used to test the association between groups, P-value of less than 0.05 was considered significant. RESULTS: A total of 1864489 blood donations were evaluated. There were 1840 confirmed HTLV-1 positive donations (0.098%). None were positive for anti-HTLV-2. The overall HTLV-1 prevalence was 98.7 per 100,000 donations during the 5 year period. Seroprevalence was higher among females, married and older blood donors. The overall seropositivity among first time, regular and lapsed donors was, 0.29% (290/100000), 0.001% (1/100000) and 0.02% (20/100000) respectively. A significant difference was observed between regular and the first time (p <0.0001) and also between lapsed and regular blood donors (p <0.0001). Most of the HTLV-1 seropositive blood donors (175 per 100,000) were from northeastern regions. We observed a gradual decline in overall HTLV-1 prevalence during the course of the study, the prevalence rate decreased from 0.13% (130/100000) in 2009 to 0.07% (70/100000) in 2013. CONCLUSIONS: The Seroprevalence of HTLV-1 among Iranian blood donors in the regions of our study still is considerable, but there is an obvious declining prevalence over the course of present study. Blood transfusion centers should continually evaluate the residual risk of infection in the country, especially in endemic areas.

Platelet Septic Transfusion Reactions in Patients With Hemato-Oncological Diseases.

BACKGROUND & OBJECTIVE: Bacterial, contamination of blood components are a significant risk for transfusion reactions. Inherently, platelet concentrates (PCs) are vulnerable to bacterial contamination, due to the storage condition of processed PCs at room temperature, which provide very suitable conditions for the proliferation of microorganisms.The current study aimed at investigating the transfusion associated septic reaction rate in patients with hemato-oncological diseases in Imam Khomeini Hospital, Tehran, Iran, and identifying the contaminating bacteria. METHODS: A total of 3056 adult patients of the Cancer Center of Imam Khomeini Hospital in Tehran transfused with PCs were studied based on the clinical symptoms of septic transfusion reaction from June 1, 2010 to May 31, 2011. Patient presented with the criteria of reaction and the residual components were evaluated for bacterial contamination by Bac T/Alert system. RESULTS: Patients with leukemia or lymphoma transfused with random-donor PCs were evaluated the signs and symptoms of transfusion reaction occurred only in 12 (%0.4) cases. Automated cultivation found 3 positive blood cultures. Among these a male recipient was categorized as possible septic transfusion reaction and Citrobacterfreundii was isolated from blood sample. CONCLUSION: Appropriate clinical utilization of PCs transfusion, and ongoing vigilance to recognize, investigate, promptly treat, and report all suspicious transfusion reactions are necessary to manage the transfusion complication including transfusion-transmitted infections (TTI).

The Prevalence of SEN Virus and Occult Hepatitis B (OBI) Virus Infection Among Blood Donors in Ahvaz City.

BACKGROUND: The SEN virus (SENV) is a prevalent blood borne pathogen that has a worldwide incidence. SENV is comprised of eight genotypes; genotypes H and D are frequently associated with the pathogenesis of non-A - E hepatitis and post-transfusion hepatitis in blood donors and hepatitis patients. So far, no SENV pathogenesis has been reported in the liver biopsies of SENV carriers, but the frequency of SENV and its related genotypes requires further molecular epidemiology studies in different regions of the world. Occult hepatitis B infection (OBI) is another global public health problem that is primarily transmitted via blood transfusions. Therefore, the identification of OBI among blood donors is key to preventing the spread of this disease. The relationship between SENV and OBI requires further evaluation. OBJECTIVES: The aim of this study was to determine the prevalence of SENV-D and SENV-H in blood donors in Ahvaz city with a particular focus on co-infection with OBI. PATIENTS AND METHODS: This study had a cross-sectional design and included 184 healthy consecutive blood donors who visited a blood transfusion center in Ahvaz city from October-November 2013. The sera of all blood donors negative for HBsAg, anti-HCV antibody, and anti-HIV antibody were tested for SENV-D and SENV-H using nested polymerase chain reaction (PCR). In addition, tests for HBV DNA (PCR), HBcIgG (ELISA), liver function (aspartate transaminase and alanine transaminase), and alkaline phosphatase were carried out. RESULTS: Liver function tests in the healthy blood donors were within the normal range. The incidence rates of SENV-D and SENV-H in the 184 total blood donors were 10 (5.4%) (95% confidence interval (CI): 2.1% - 9.0%) and 32 (17.4%) cases (95% CI: 12.0% - 23.0%), respectively. SENV-H/D co-infection occurred in 2 (1.1%) patients. The sera of 8/184 (4.3%) were positive for anti-HBc antibody but negative for HBV DNA. CONCLUSIONS: Regardless of the presence of nonpathogenic SENV, 44/184 (24%) blood donors tested positive for both SENV-D and SENV-H. Although 4.3% of blood donors were positive for HBcIgG but negative for HBV DNA, the presence of OBI cannot be ruled out unless their liver biopsies show negative for HBV DNA.

Prevalence of Toxoplasma gondii among Iranian Blood Donors: A Narrative Review Article.

BACKGROUND: Toxoplasmosis is a common parasitic disease. There is likelihood of exposure to Toxoplasma gondii in blood donors during the periods of life. Currently, laboratory screening of blood donors for T. gondii is not routinely available. The objectives of this review were to study the effects of T. gondii on blood safety and to approach for risk reduction in blood recipients. METHODS: A literature search was performed using Cochrane library, PubMed, Scopus, Google scholar IranMedex, SID and Magiran without time limitation. All studies, which had reported the prevalence of T. gondii in Iranian blood donors in both English and Farsi languages, were evaluated and reviewed. The contents of the transfusion medicine text books related to this issue were reviewed. Searching keywords were "Blood Donors" or "Blood Transfusion" and "Toxoplasma" or "Toxoplasmosis" and Iran. RESULTS: In order to study the prevalence of T. gondii in Iranian blood donors, six studies have been reviewed. IgG and IgM antibodies varied between 12.3% to 52.8% and 0% to 5.47%. Some of these studies have suggested to doing the screening for all blood donors. However, based on parasitological and epidemiological evidences, there is little chance for parasite transmission by blood transfusion. CONCLUSION: By considering the moderate prevalence, difficulty in the differentiation between recent and past infections, and cost-effectiveness, it is not possible and rational to perform screening of donated blood. To reduce the risk of parasite transmission, leukofilteration method is recommended.

Prevalence of antibody to Hepatitis B core antigen and Hepatitis B virus DNA in HBsAg negative healthy blood donors.

BACKGROUND: Hepatitis B virus is one of the most important blood born viruses. Although the sensitivity of screening tests has been considerably increased, transmission may still occur due to window period or occult hepatitis B infections (OBIs). This study was aimed at evaluating the prevalence of the anti-HBc and identifying the HBV DNA in HBsAg negative blood donors. METHODS: The Blood samples from 2031 HBsAg-negative blood donors were divided into three aliquots and tested for anti-HBc, anti-HBs and HBV DNA. Serologic screening including anti-HBc and anti-HBs was performed. As a confirmatory test, all positive results for anti-HBc were retested with another kit. Two positive results were considered for anti-HBc positivity. All HBsAg negative selected donations were tested by PCR assay on pooled specimens (five samples per pool), plasma samples found to be HBsAg negative but anti-HBc positive were selected for a single-unit specimen Real-Time assay. RESULTS: The study population had a mean age of 33.25 ± 10.09 years were mainly composed of males (94.8 %). The seroprevalance rate was 4.9 % for Anti-HBc and 31.9 % for HBsAb. The majority (58.6 %) of Anti-HBc positive cases were regular blood donors with 42-49 years being the largest age group (41.4 %). Neither individual NAT nor pooled NAT test detected any HBV DNA. CONCLUSION: However, Screening of anti-HBc Ab is proposed as a method to identify previous contact with HBV, but there is controversy in literature data regarding the cost-benefit of exclusion of positive anti-HBc Ab in blood donors. Our data does not suggest HBc-Ab test as a screening tool in the study setting.

Variations in Intraplatelet Phospho-VASP Expression Due to Pre-analytical Sample Preparations, Illustration of a Quality Control Issue in Platelet Pharmacology.

Intraplatelet vasodilator-stimulated phosphoprotein (VASP) analysis is a commonly used laboratory approach for monitoring of the anti-platelet therapy with adenosine diphosphate (ADP) receptor blocking agents; however, it's testing in clinical laboratory needs a high level of experience and proficiency. The ability to recognize how the pre-analytical variations can change the results would be helpful for the interpretation of data from intraplatelet VASP analysis. The aim of this study was to describe the possible differences of intraplatelet phospho-VASP expression between washed and platelet rich plasma (PRP) samples, both at baseline levels and following experimentally induction of VASP phosphorylation. PRP and washed platelet samples were treated with different inducers of VASP phosphorylation, including forskolin (10 µM), prostaglandin E1 (PGE1) (50 nM) and sodium nitro-prusside (SNP) (100 µM). Untreated PRP and washed platelet samples were also included in study as baseline controls. After labeling of platelets with either anti P-Serine(157)-VASP or anti P-Serine(239)-VASP, the samples were subjected to flow cytometric analysis to monitor the levels of intraplatelet phospho-VASP expression. Washed platelet samples tend to show increased expression of intraplatelet P-Serine(157)-VASP at baseline state and also more expression of P-Serine(157)-VASP and P-Serine(239)-VASP in response to forskolin and SNP, compared with PRP samples. Though, reduced levels of PGE1-induced VASP phosphorylation at both residues were detected for washed platelets. In this study we have provided some background information required for performing of intraplatelet VASP analysis on differently handled platelet samples and interpretation of the obtained results.

Seroepidemiology of human T-cell lymphotropic virus type-1 (HTLV1) in Mashhad.

INTRODUCTION: Human T-cell lymphotropic virus (HTLV-I) is associated with adult T cell leukemia/lymphoma (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The major routes of HTLV-I transmission are mother-to-child, sexual contact, and blood transfusion. Mashhad is one of the main endemic areas in the world for HTLV-I, and minimizing the risk of HTLV-I transmission through blood transfusion is one of the main duties of the Blood Transfusion Center in Mashhad. The aim of this study was to determine the prevalence of HTLV-I in the blood donor population in Mashhad during 2011-2013. METHODS: All the blood donors in Mashhad from March 2011 to April 2013 who were diagnosed with HTLV-I on the ELISA screening test and the Western blot confirmatory test were included in this seroepidemiological study. RESULTS: From 174,662 blood donors, 327 donors were confirmed to be infected with HTLV-I according to Western blot assay. The seropositive donors ranged in age from 17 to 59, and their mean age was 39.88±10.49 years. The overall prevalence rates of HTLV-I infection were calculated as 0.18% and 0.19%, respectively. CONCLUSION: Due to the lower frequency of infection in regular blood donors, younger individuals, and people with higher education levels, the selection of blood donors from these populations should be further considered.

Interferon alpha-2b therapy in chronic hepatitis delta.

BACKGROUND: Approximately 5% of hepatitis B virus (HBV) carriers are coinfected with hepatitis D virus (HDV). HBV/HDV coinfection is a major cause of cirrhosis and end stage liver disease in chronic HBsAg carriers. The only approved therapy for chronic hepatitis delta is interferon alpha (IFN α) in either pegylated or conventional forms. Although higher doses and longer durations of IFN α therapy in HBV/HDV coinfected patients are currently applied, yet treatment response is low. OBJECTIVES: We aimed to determine the efficacy of IFN α-2b therapy in patients with HBV/HDV coinfection. PATIENTS AND METHODS: In this cross sectional study, 20 HBsAg carriers with positive Anti-HDVAb and RT-PCR for HDV RNA were recruited and treated for three year duration with 5 million units (MU) of IFN α-2b, three times weekly or one year with 5 MU of IFN α-2b daily. Sustained virological response (SVR) was defined as a negative qualitative HDV RT-PCR, 6 months after treatment cessation. RESULTS: Overall, 3 (15%) subjects achieved SVR, 10 cases (50%) relapsed after treatment cessation and 7 (35%) patients did not clear HDV during the treatment. CONCLUSIONS: HDV coinfection with HBV had very low response rate to high doses and long durations of IFN α-2b therapy.

Evolutionary analysis of HBV "S" antigen genetic diversity in Iranian blood donors: a nationwide study.

The genetic diversity of the HBV S gene has a significant impact on the prophylaxis and treatment of hepatitis B infection. The effect of selective pressure on this genetic alteration has not yet been studied in Iranian blood donors. To explore HBV evolution and to analyze the effects and patterns of hepatitis B surface antigen (HBsAg) mutations on blood screening assays, 358 Iranian blood donors diagnosed as asymptomatic HBV carriers were enrolled in this nationwide study. Large S and partial S genes were amplified and sequenced. HBV (sub) genotypes and synonymous and nonsynonymous mutations were investigated. The impact of naturally occurring mutations on HBsAg ELISA results was explored. Phylogenetic analyses revealed that isolated strains were of genotype D. The dominant subgenotype/subtype was D1/ayw2. Deletions and naturally occurring stop codons in the pre-S1 and major hydrophilic region (MHR) were identified. In total, 32.8% of the studied strains harbored 195 single or multiple mutations in the MHR, the majority of which were located at the first loop of the "a determinant" domain. The ayw2 subtype showed a significant effect on the ELISA signal/cut-off value and carried fewer mutations in the MHR. Nonsynonymous/synonymous substitution value indicated that negative selection was the dominant evolutionary force in the HBV S gene. This nationwide study revealed that mutation frequency of HBsAg among Iranian blood donors was much higher than previous reports from the different local regions. These findings regarding the significant differences in reactivity of ELISA among different subtypes of HBV and its correlation with the number of mutations at the MHR will be valuable to public health authorities.

Emerging infectious threats to the blood supply: seroepidemiological studies in iran - a review.

SUMMARY: The risk of transfusion-transmitted infections has been greatly reduced by improvements in donor screening and testing. However, newly recognized blood-borne infectious agents can be threats to blood safety. In order to evaluate the prevalence some of these agents in blood donors, a systematic review was conducted. Data were obtained from published papers related to HGV, Torque Teno virus (TTV), HTLV, West Nile virus (WNV) and SEN virus (SEN-V). Based on these studies, the prevalence of HGV varied from 1 to 8.6% for anti-E2 and from 0 to 4.8% for HGV RNA. The prevalence of TTV DNA and HTLV-I varied from 2.7 to 79.5% and from 0.013 to 2.3%, respectively. The WNV-specific IgM antibody and WNV RNA are negative in blood donors. Prevalence rates of SEN-V in Iranian blood donors range from 23 to 90.8%. Consequences of these infectious agents for blood safety are different. Thus, the need to perform laboratory screening as well as effectiveness and efficiency of laboratory tests depend on pathogenicity level and epidemiological conditions of emerging infections. However, being prepared based on the current level of risk and interventions to reduce the risk can be effective in reducing the potential threat for blood supply.

The frequency of HHV-8 infection in otherwise healthy blood donors as well as renal allograft recipients living in Iran.

BACKGROUND: Different reports from Middle East countries demonstrated Kaposi's sarcoma (KS) in transplant population. This vascular malignancy occurs mostly among immunocompromised individuals. Human herpesvirus 8 (HHV-8) appears to be the causative factor for the development of this neoplasm. Transplant programs are concerned about the frequencies of HHV-8 infection either in general population or transplant patients. METHODS: The current study was conducted in two phases. Firstly, we detected antibodies against HHV-8 in 790 otherwise healthy blood donors. Secondly, a total of 125 kidney allograft recipients evaluated as being seropositive for HHV-8. We utilized enzyme immunoassay (EIA) for serologic studies. RESULTS: Among blood donors, the male to female ratio was 1.05 (405 vs. 385 ) while the mean age was 38.9 ± 11.7 years. The serostatus of none of these blood donors were positive for HHV-8. Among kidney recipients, the male to female ratio was 1.9 (82 vs. 43). The mean age was 39.01 ± 14.77 years. Two (1.6%) patients were seropositive for HHV-8. CONCLUSION: The prevalence of HHV-8 infection among Iranians is likely to be low. Yet, owing to the evidence of this infection among kidney allograft recipients and its probable role in developing post- transplantation KS (PT-KS), further studies appear to be required to keep the various aspects of this infection under close surveillance.

Efficacy of the confidential unit exclusion option in blood donors in tehran, iran, determined by using the nucleic Acid testing method in 2008 and 2009.

BACKGROUND: In recent years, the confidential unit exclusion (CUE) option has been used to increase blood safety at blood transfusion centers in several countries. The epidemiologic characteristics of diseases and demographic characteristics of patients vary in different countries; therefore, we investigated whether the CUE option is useful in Iran. In this study, we determined the prevalences of hepatitis B virus (HBV) and hepatitis C virus (HCV) in CUE-positive and CUE-negative units, as well as the efficacy of the CUE option. OBJECTIVES: The aim of this study was to evaluate the efficacy of the CUE option in reducing the prevalences of HBV and HCV in blood units. PATIENTS AND METHODS: All donors were tested for the HCV antibody (anti-HCV) and hepatitis B surface antigen (HBsAg). Supplemental tests were performed to confirm the presence of viruses in the units that tested positive. In total, 2000 units (1000 CUE-positive units and 1000 CUE-negative units) were tested using the nucleic acid testing (NAT) method. The prevalence of infectious markers was estimated in all demographic subgroups. RESULTS: The prevalences of HBV and HCV markers were higher in donors who opted for CUE than in those who did not. The CUE option had low sensitivity (21.5%) and positive predictive value (PPV; 20.9%) for the markers. Most of the donors who opted for CUE for the first time were men with low levels of education. CONCLUSIONS: The CUE option has low sensitivity and PPV, and its effectiveness in reducing the transmission of infectious diseases through window-period units is minimal. The CUE process can be continued in Iran because Iran is geographically located in a region where HBV is endemic; however, higher levels of education are necessary to make this process effective.

Antibody titration and immune response of Iranian beta-thalassemic patients to hepatitis B virus vaccine (booster effect).

BACKGROUND: Thalassemia is hereditary anemia with lifelong transfusion as treatment and hepatitis B virus (HBV) infection is one of the transfusion transmitted infections (TTI). HBV vaccination is obligatory for these patients by 3 double-dose injections. The authors studied the HBV status and immune response to vaccination by hepatitis B surface antibody (HBsAb) titration in their thalassemic patients. They also compared these results with their previous study to find out the effectiveness of a booster dose in the immunity of patients against HBV. MATERIALS AND METHODS: Hepatitis B surface antigen (HBsAg), HBsAb, and hepatitis B core antibody (HBcAb) were detected in sera of 416 patients at the Tehran Adult Thalassemia Clinic. The immune status was classified into 4 categories: (1) immune to HBV via the vaccination (positive vaccinal)--if HBs Ag: negative, HBsAb: positive, HBcAb: negative; (2) immune to HBV via the natural disease (past infection)--if HBs: negative, HBsAb and HBcAb: both positive; (3) nonimmune to HBV (negative)--if all three parameters were negative; (4) carrier of HBV (carrier state)--if HBs Ag was positive and HBsAb and HBc Ab: both negative. Also grading of immunity done by HBsAb titration as positive if HBsAb titer was more than 100 IU/mL, negative if HBsAb titer was less than 10 IU/mL, and weakly positive if antibody level was 10-100 IU/mL. RESULTS: There were 416 patients: 302 (72.5%) with thalassemia major (TM), 104 (25%) thalassemia intermedia (TI), 7 (1.6%) sickle thalassemia (ST), and 3(0.7%) alpha-thalassemia (HbH disease). The mean age was 25.6 +/- 8.3 yr and median age was 24 yr; there were 247 (59.4%) males and 169 (40.6%) females. A total of 257 patients (61.7%) were splenectomized. According to our classification 289 (69.4%) were immunized by vaccination; 80 (19.2%) were immunized by past infection; 44 (10.5%) were negative, and 3 (0.7%) were in carrier state of HBV. In grading of immunity to HBV vaccination, 319 (76.6%) patients had HBsAb > 100 IU/mL (positive), 77 (18.5%) between 10 and 100 IU/mL (weakly positive), and 20 (4.8%) less than 10 IU/mL (negative). There was no significant correlation between the level of HBsAb and splenectomy or type of thalassemia. CONCLUSION: Response rate to vaccination is more than 95% after complete course (3 doses) in healthy individuals but failure to fulfill vaccination seems a problem in chronic transfused patients. These results reflect advantages of a booster dose of vaccine, which increased the protection level among these high-risk patients from 46.9% (in the authors' previous data) up to 69.4% in this study.