hepatitis b virus ( hbv ) infection is a major global problem , with about two billion people now infected despite the availability of an efficacious vaccine . it has been estimated that there are more than 350 million carriers of hbv in the world and that roughly one million of them die annually from hbv - related liver disease ( 13 ) . the prevalence of hepatitis b infection varies in different parts of the world , ranging from less than 1% to 15% . in the middle east , the endemicity is intermittent , with a carrier rate of 2 to 8% ( 47 ) . transmission of hbv can occur through sexual intercourse , parenteral contact , or from an infected mother to a baby at birth ( 1 ) . hbv transmission has similar characteristics to the transmission of hiv in that the virus has been detected in peripheral mononuclear cells ; in tissue from the pancreas , kidneys , skin , and spleen ; and in bodily fluids , including semen , breast milk , sweat , tears , urine , and vaginal secretions ( 1 , 8) . hepatitis b core antibody ( hbc ab ) is the first antibody produced after infection with hbv , and it is the only detectable marker in the window period . it is in the serum of recovered individuals and also those with chronic hepatitis b ( chb ) . resolved infections usually reveal hepatitis b surface antibodies ( hbs ab ) ( 2 , 3 ) . isolated hbc ab refers to the presence of hbc ab in sera without hepatitis b surface antigen ( hbs ag ) or hbs ab . it may be an indicator of resolved hbv infection in which hbs ab had declined to an undetectable level , or it may be an indicator of chronic infection , such that hbs ag can not be detected due to protein mutation , which makes it undetectable by certain diagnostic assays ( 9 ) . recent studies have indicated that we can not judge the hbv infection based only on the presence or absence of hbs ag and hbs ab ( 10 ) . despite the decrease in hbv infections globally , the use of serological markers for screening blood donors is still important , since hbv remains a great risk for patients who receive blood transfusions ( 11 , 12 ) . the objective of our study was to evaluate the seroprevalence of hbc ab among healthy blood donors in bandar abbas city in the south of iran . this cross - sectional study was conducted in 2012 in bandar abbas , the capital city of hormozgan province in the south of iran . for the purposes of the study , 1000 people were selected for participation from first - time , voluntary blood donors who came to the blood transfusion organization in bandar abbas city . the study was approved by the ethics committee at the hormozgan university of medical sciences , and a written , informed - consent form was obtained from the donors . the participants were asked questions regarding the frequency of blood donation , past surgical procedures , and other risk factors related to hepatitis b and c transmission . after the informed - consent forms were signed , physical examinations were conducted , and blood samples were drawn for testing . all donors who came to the department of transfusion medicine during the study period and met the general criteria for blood donation were included in the study . donors who did not meet these criteria were not allowed to donate blood , and , hence , they were excluded from the study . potential donors with medical histories that included symptoms suggestive of acquired immunodeficiency syndrome , a history of jaundice , a blood transfusion in the last year , or close contact with a patient suffering from hepatitis in the last six months also were not allowed to donate blood . detailed histories were obtained and clinical examinations were performed for all the donors by qualified staff members who had been trained to screen potential blood donors . according to the policy of the iranian blood transfusion organization , all donors were checked for hbs ag , hcv ab , and hiv by the elisa method . based on the results of these tests , all of the participants were deemed to be healthy and eligible to donate blood . five milliliters of blood were collected from each donor in a sterile , capped tube . then , the blood was centrifuged , and two aliquots of the plasma were separated and stored at 70 c until it was needed for testing . the screening for the hepatitis b core antibody ( anti - hbc igm and igg ) was done by a chemiluminescence kit made by diasorin liaison. all of the steps were followed according to the manufacturer s instructions . the presence or absence of anti - hbc antibodies the chi - squared test was used to detect any significant correlations between the different variables . one thousand samples were collected from participants during one year , and the vast majority of the participants were males ( 954 : 95.4% ) . out of the 1000 samples studied , 83 of them were found to be positive for hbc ab . the prevalence rate of hbc ab was [ ( 83/1000 )  100% = 8.3% ] . table 3 indicates that there was a greater prevalence of hbc ab among younger people , but the relationship between age and hbc ab results was not significant ( p value > 0.05 ) . among the 83 people who tested positive for hbc ab positive , 60 of them ( 72.3% ) tested positive for hbs ab positive as well , and 23 of them ( 27.7% ) tested negative for hbs ab negative . of the 23 participants who tested positive for anti - hbc and negative for anti - hbs , 21 ( 91.3% ) were males and 2 ( 8.7 % ) were females . infection by the hepatitis b virus is a public health problem and a major cause of morbidity and mortality , particularly in developing countries ( 6 ) . the world can be divided into three areas based on the prevalence of chronic hbv infection , i.e. , high ( > 8% ) , intermediate ( 28% ) , and low ( < 2% ) ( 6 , 7 ) . most countries in the world are still considered intermediate to high endemicity for hbv infection ( 6 , 7 ) . in iran the prevalence of hepatitis b varies from 1.3 to 6.3% , depending on the different areas of the country ( 13 ) . transfusion of blood collected from a donor who is in the window period may lead to post transfusion hepatitis b in the recipient ( 14 , 15 ) . at present , the detection of hbsag is the only diagnostic screening test for hbv infection in blood transfusion centers in iran . we examined 1000 serum samples from healthy donors that tested negative for hbsag and found that 8.3% of them were positive for anti - hbc . previous studies have demonstrated the presence of hbv dna in anti - hbc - only donors ( 16 , 17 ) . these findings corroborate the findings of an earlier report that indicated that testing blood donors for hbsag alone is not sufficient to eliminate hbv from the blood supply ( 18 ) . observed the presence of hbv dna in 20% of anti - hbc - only donors studied and stated that reactivity to anti - hbc can only predict cryptic hbv infection ( 17 ) . a report from japan ( 16 ) demonstrated the presence of hbv dna in 38% of donors who were hbsag - negative and anti - hbc - reactive . it was observed earlier ( 14 , 15 , 19 ) that the screening test for the detection of hbsag does not rule out the transmission of hepatitis b , because the donor might be in the  window period ,  and only the detection of the antibody to the hepatitis b core - type antigen hbcigm serves as a useful serological marker during this period . a prevalence of 8.3% observed for anti - hbc in this study was significantly greater than the 0.39% observed by kumar et al . this might indicate that the possibility of transfusing hbv through blood donation is increasing progressively . anti - hbc has been found to be an excellent indicator of occult hbv infection during the window period ( 15 , 20 , 21 ) . other markers for detecting occult hbv infection in an hbsag negative blood donor , such as detection of hbv dna by polymerase chain reaction ( pcr ) , may not be cost effective ( 22 ) . detection of anti - hbc has contributed significantly to the reduction of the incidents of post - transfusion hepatitis b among patients ( 23 , 24 ) . the igm class of the anti - hbc is a marker that indicates recent infection . the igg variety of anti - hbc appears later during the infection and points to a past hbv infection . individuals with the igg variety of anti - hbc may not be infectious because they may have sufficiently high titers of antibodies to hbsag ( anti - hbs ) , which are protective in nature , and the affected individuals may actually be disease free . the results of the study showed that 8.3% of 1000 blood donors tested positive for anti - hbc antibodies . it shows the need to include anti - hbcigm in routine screening of blood donors in iran . it also confirmed the fact that testing blood donors for hbsag alone is not sufficient to eliminate hbv from the blood supply . although the possibility of achieving zero risk of transfusion - associated hbv infection depends largely on dna testing of all of the units of blood collected before they are used in transfusions , this can not done in many developing countries , including iran , due to cost . thus , it is recommended that anti - hbcigm be included in the routine screening of blood donors in countries where dna testing is not done . this will make a significant contribution to the reduction of transfusion - associated hepatitis b virus infections .
background : the risk of infection with transfusion - transmitted viruses , such as hepatitis b virus ( hbv ) , has been reduced markedly . however 
 , a zero - risk blood supply remains a popular goal . 
 anti - hepatitis b core antigen ( anti - hbc ) is considered to be an effective marker for occult hbv infection , and it has served a significant role in improving blood safety . 
 the purpose of this study was to determine the seroprevalence of anti - hbc antibodies among blood donors.methods:during a period of six months in 2012 , 1000 blood donors in bandar abbas were investigated for the presence of hbv infection markers . 
 we used elisa for the detection of hbsag and chemiluminescence for the detection of hbsab and anti - hbc antibodies.results:the prevalence of positive anti - hbc among the 1000 donors was 8.3% . 
 almost 2.3% of the donors were reactive for anti - hbc and negative for hbsag.conclusions:the study showed that more than 2% of healthy blood donors in bandar abbas already have been exposed to hbv , although their hbsag tests were negative . 
 we suggest screening for anti - hbc to improve the safety of the blood supply .