the b19 is a small , simple virus with a linear single - stranded dna and is the only member of the parvoviridae family , which is pathogenic to humans ( 1 - 5 ) . this virus is resistant to most physicochemical factors and is mainly transmitted through respiratory secretions ; however , it can be transmitted through blood and blood products ( 6 , 7 ) . during the production of blood products , the common deactivation stages of the virus can not prevent parvovirus b19 transmission and the blood recipients may get infected . thalassemia patients who often receive blood products are at risk of virus b19 infection . in addition , these patients are at risk of acquiring serious diseases transmitted through blood and blood products ( 7 - 9 ) . in immunologically healthy hosts , b19 infection can be benign or can occur without any signs or may cause erythema infectious in children and acute arthropathy in adults . in immunosuppressed patients , b19 infection may persist and lead to pure red cell aplasia , chronic anemia , and , less frequently , thrombocytopenia , pancytopenia , and neutropenia ( 10 - 12 ) . during pregnancy , the virus can be transferred to the uterus , resulting in hydrops fetalis and fetal death ( 13 ) . patients with blood disorders are at risk of sever clinical diseases , especially those with chronic hemolytic anemia such as thalassemia , sickle cell anemia , and hereditary spherocytosis . in these patients , the rate of erythroid progenitor cell formation increases to compensate for the lysis of red blood cells . parvovirus b19 infection can suppress erythropoiesis and induce acute erythroblastopenia , which is often referred to as transient aplastic crisis . this temporary halt in the production of red blood cells occurs only in patients with chronic hemolytic anemia due to the short lifespan of red blood cells . the risk of b19 transmission increases in these patients ( 5 , 14 , 15 ) . reported the incidence of common b19 virus infection in leukemia , malignant lymphoma , chronic anemia , and thalassemia patients . overall , their results showed that patients with malignant diseases , immunosuppressive diseases , or hemolytic anemia are at high risk of b19 infection , and the relationship between these diseases and b19 infection has been confirmed ( 16 ) . most published studies in iran have described the prevalence and detection of antibodies against parvovirus b19 by using serological methods such as enzyme - linked immunosorbent assay ( elisa ) . on the other hand , there is no information about the relationship between active b19 infection and thalassemia in iran , and hence , it is very important to determine the rate of active b19 infection in apparently healthy individuals and thalassemia major patients . in this study , nested polymerase chain reaction ( pcr ) assay , which has high sensitivity , was used for the genomic detection of parvovirus b19 in thalassemia patients in the isfahan province . moreover , the relationships between possible risk factors such as age , gender , and history of blood transfusion and b19 infection were evaluated using statistical analysis . any data on confirmation of b19 infection and other factors may be useful for the treatment , management , and prevention of b19 infection . in this cross - sectional study , 30 patients were randomly selected from inpatients a hospitalized in the thalassemia and hemophilia wards in seyed - al - shohada hospital in isfahan . 30 apparently healthy individuals without a history of thalassemia and in the same age range as the patients were selected as the controls . the indexes of blood factors of the b19-infected and uninfected patients were recorded and statistically analyzed . whole blood samples were collected in vacuum tubes containing ethylenediaminetetraacetic acid and plasma samples were prepared by centrifugation at 1500 rpm for 5 min and were aliquoted ( 500 l ) in microtubes and stored at -20c until analysis . demographic date on gender , age , duration of disease , laboratory findings regarding the number and characteristics of red and white blood cells , and history of blood transfusion were recorded in data forms . the chi - square test at a confidence level of 95% ( p < 0.05 ) and student t - test were used . extraction of viral dna from the plasma samples from the patients was performed using the gf-1 viral nucleic acid extraction kit ( vivantis , usa ) , according to the manufacturer instructions and the extracted dna was stored at -70c . the nested pcr method described by zerbini et al . ( 2011 ) was used for detecting specific viral dna sequences ( 17 , 18 ) . this method is > 10,000 times more sensitive than the standard pcr method . to control contamination and verify the absence of inhibitors of pcr , distilled water was used as the negative control and a positive serum sample containing the b19 genome the materials required in this method are as follows : 25 l of reaction mixture containing 2.5 l of 10 pcr buffer , 1 l of 10 mm dntp mixture , 1.5 l of 50 mm mgcl2 , 0.5 l of taq dna polymerase ( 5 u/l ) , 1 l of each forward and reverse primer ( 10 pmol/l ) , 14.5 l of deionized water ( tag copenhagen , denmark ) , and 3 l of extracted dna sample . 1a and 2s primers were used at the first stage , and 3a and 4s primers were used at the second stage ( table 1 ) . thirty - five cycles were used in both the stages of pcr with the following temperature conditions : 95c for 1 minute , 55c for 1.5 minutes , and 72c for 1 minute , followed by final extension at 72c for 7 minutes . at the second stage of nested - pcr , 2 l of the recent reaction mixture finally , the pcr products were analyzed by gel electrophoresis in 2% agarose gel and were evaluated on the basis of the position of the dna marker bands on the gel , the amount of product in the first stage was 1112 bp and that in the second stage was 104 bp . the thalassemia subjects comprised 15 ( 50% ) female and 15 ( 50% ) male patients , whereas the control group comprised 12 ( 40% ) female and 18 ( 60% ) male patients . the chi - square test showed a significant difference between the thalassemia and control groups ( table 2 ) . parvovirus b19-infected and uninfected patients in the thalassemia group were analyzed in terms of gender , age , and history of blood transfusion by using the chi - square test . statistical analysis of the possible risk factors for b19 infection showed no significant differences in gender , age , and history of blood transfusion between the b19-infected and uninfected patients ( table 3 ) . the student t - test was used to assess the differences in the quantitative variables including the values of the hematological parameters investigated between the b19-infected and uninfected patients . differences in the descriptive indicators of the hematological parameters between the b19-infected and uninfected thalassemia patients are shown in table 5 . pcr analysis showed that parvovirus b19-specific nucleotide sequences were present in 20% of the thalassemia patients , which is consistent with the results of previous studies conducted in other countries . although the immunoglobulin g ( igg ) concentration was high in the serological tests , the immunoglobulin m ( igm ) and dna concentrations were reported to be in the same range . in a study by siritantikorn , some evidence of active b19 infection was found in 13% of the thalassemia patients . moreover , the prevalence of anti - parvovirus b19 igg was 38% and that of anti - parvovirus b19 igm was only 4% in the patients . the prevalence of viral dna and anti - b19 igg was higher in thalassemia patients with no history of blood transfusion than in those who received blood products , which can be owing to the low prevalence of b19 infection in blood donors in thailand ( 6 ) . in another study by kishore the prevalence of anti - b19 igm was 41.1% in the thalassemia major patients and 6.2% in the control patients without any blood disorders . moreover , the prevalence of anti - b19 igg was 81% in the study patients and 21% in the control patients ( 9 ) . in a study by regaya in tunisia , the prevalence of anti - b19 igg was 56.5% in patients with chronic blood disorders , while viral dna was reported in only 8.7% of the patients , which is lower than that reported in our study ( 5 ) . in another study in turkey , the prevalence of viral dna and igm antibodies was 29.1% ( 16 ) . the prevalence of anti - b19 igm , which represents new or acute infection , was 17.1% in children with hematologic malignancies ( 19 ) . in a study by gupta et al . b19 dna was reported in 27.3% of 66 patients with aplastic anemia , as compared to 2.2% of the control patients . furthermore , the prevalence of anti - b19 igm was 25.8% in the study patients and 2.2% in the control patients ( 20 ) . in the present study , statistical analysis of possible risk factors for b19 infection showed no significant differences in gender , age , history of blood transfusion , and hematological parameters between the b19-infected and uninfected patients . however , the white blood cell count , hemoglobin level , hematocrit level , platelet count , mean corpuscular volume , and mean corpuscular hemoglobin level were decreased in thalassemia patients with parvovirus b19 dna . many studies reported that the prevalence of parvovirus b19 infection increased with age among populations ( 6 ) . moreover , an increase in the prevalence of parvovirus b19 infection associated with blood transfusion and blood products has been reported in hong kong and taiwan ( 21 , 22 ) . some previous studies conducted in various countries showed that the prevalence of b19 infection in the investigated individuals was very high , which may be owing to those studies were conducted in groups at high risk of b19 infection such as patients suffered from hematologic disorders , immunodeficiency or leukemia . this may be owing to repeated blood transfusions in patients with hematologic disorders or immunodeficiency and lymphoid tumor lines in the patients with leukemia . b19 infection is common , but most individuals are not actively infected , as observed in previous studies conducted in iran and other countries , in which the prevalence of anti - b19 igg and viral dna was reported to be 92% and 0% , respectively , in apparently healthy individuals . similarly , in the present study , none of the control patients tested positive for b19 infection . the prevalence of b19-infection was significantly higher in hbv - infected patients than healthy control group ( 24.1% vs 4.7% ) . generally , parvovirus b19 is transmitted through respiratory secretions , but this virus can also be transmitted through blood transfusions . patients who have chronic anemia and hematologic malignancies such as leukemia , thalassemia , and hemophilia and require continuous blood infusions may receive units of red blood cells containing parvovirus b19 . the probability of acquiring transfusion - transmitted diseases is associated with exposure to infected blood units , which depends on the prevalence of asymptomatic infected blood donors in the general population . the prevalence of b19 in the blood of healthy donors has been reported to be in the range of 1 in 20,000 to 1 in 500,000 donors ( 9 , 24 ) . hence , it is needed that , the cases of chronic anemia and hematologic malignancies in which parvovirus b19 is involved to be distinguished in order to replace a suitable treatment for the patients . in cases of transient aplastic crisis caused by parvovirus b19 , erythrocyte transfusions are usually used for treatment , and intravenous immunoglobulin infusions containing antibodies neutralizing the human parvovirus are used to treat or mitigate persistent signs of b19 infection in immunocompromised or anemic patients ( 1 , 25 ) . it is recommended that all patients with hematological disorders should consider undergoing pcr screening for the presence of antibodies against the b19 virus and b19-specific nucleotide sequences for better diagnosis and treatment . however , it is recommended that further studies be performed to confirm the findings of this study and other hypotheses ( the b19 virus shows great tropism for erythroid progenitor cells and causes an increase in these cells in thalassemia patients , predisposing them to b19 replication ) .
background : parvovirus b19 , a member of the erythrovirus genus of parvoviridae family , causes various clinical illnesses including infectious erythema , arthropathy , hydrops fetalis or congenital anemia , and transient aplastic crises . 
 the b19 virus can be transmitted through respiratory secretions , blood products , and blood transfusion.objectives:the aim of this study was to detect the b19 virus in thalassemia patients in isfahan , iran.patients and methods : the prevalence of parvovirus b19 infection was compared between thalassemia major patients and healthy subjects . 
 plasma samples were collected from 30 thalassemia patients from isfahan , iran . 
 thirty patients without any blood complications were considered as the control group . 
 after dna extraction from the plasma samples , polymerase chain reaction was performed for parvovirus b19 detection.results:the parvovirus b19-specific nucleotide sequence was detected in 6 patients ( 20% ) . 
 none of the samples obtained from the 30 control subjects tested positive for b19.conclusions:in this study b19-parvovirus infection were detected in patients with hematologic disorders in comparison with control subjects . 
 screening of patients with a high risk of parvovirus b19 infection can considerably reduce the incidence and prevalence of b19 infection .