Genotype 6 appeared to show similar treatment responses to those infected with genotype 2/3, of which the SVR rates were both higher than that seen among patients infected with genotype 1 [22,23,25]. For verification, further studies are needed, which should include more patients to be matched not only with the age, gender, ethnic and geographic origins but also with HCV subtypes and basal viral loads. Blood transfusion used to be the major risk in acquiring HCV infection prior to the institution of a mandatory anti-HCV screening [37]. Since 1992 the screening has been implemented in the United States and thus the risk has declined from 1/200 per unit of blood to 1/10,000,1/10,000,000 [38]. Such a risk did not decline in China until the central government enacted the antiHCV screening in 1993 and outlawed paid blood donations in 1998 [26]. With the risk via transfusion Oltipraz biological activity greatly decreased, the risk via injection drug use (IDU) is increasing, which has now become the major risk for contracting HCV infection in China [39]. It has been argued that sexual transmission may also be a major risk for HCV infection especially among male IDUs who have sex with men or with prostitutes [40,41]. In addition, high viral loads has been indicated to increase the risk of HCV vertical and needlestick transmissions [42,43]. Concurrent with a recent transition in the risk from transfusion to IDU, the prevalence of 6a is increasing while 1b is decreasing. As we know, 1b has been regarded to be more associated with HCV transmission via blood transfusion while 6a 
typically linked to IDU and sexual transmission [12]. In this study, all blood donors were asked to answer a standardized questionnaire before blood donations which listed all the knownrisk factors. Donors would be excluded when having a history of transfusion of blood or blood products, IDU, receiving a tattoo, ear or body piercing, surgery, or other invasive medical procedures. Follow-up studies were also performed on those who were HCV viremic. However, only a small proportion of the donors confessed having these risks (data not shown). It is concerning that 4 IBP site subtype 6a might have spread to the general population via the IDU network or through illegal sexual workers. In this regard, a significantly higher proportion of male, found among donors infected with 6a than with other HCV genotypes, is implicative. We found that the percentage of male donors who were HCV viremic is about 3.8 times as many as that of the female donors (79.2 versus 20.8 ), while in initial screening a total of 707 voluntary blood donors were detected to be positive for anti-HCV among whom the male/female ratio is about 2.5 (503/204). It has been reported that women are more likely to clear the virus spontaneously after acute infection [44,45]. This can be interpreted that men are more likely to develop chronic hepatitis than women and continue to be HCV viremic. The interpretation helps to explain why male donors tended to have higher levels of HCV RNA than female donors (6.06 versus 5.69 log 10 IU/ml), which is consistent with the results from a very recent large-scale study based on a multi-ethnic group of IDUs [29]. We firmly believe that the outcomes of HCV infection among women are much better than among men. In support of this belief, there exist additional lines of evidence: 1) HCV is more likely to infect men. In the USA, the prevalence of anti-HCV among men was twice as that among women [4]. In one of our recent studi.Genotype 6 appeared to show similar treatment responses to those infected with genotype 2/3, of which the SVR rates were both higher than that seen among patients infected with genotype 1 [22,23,25]. For verification, further studies are needed, which should include more patients to be matched not only with the age, gender, ethnic and geographic origins but also with HCV subtypes and basal viral loads. Blood transfusion used to be the major risk in acquiring HCV infection prior to the institution of a mandatory anti-HCV screening [37]. Since 1992 the screening has been implemented in the United States and thus the risk has declined from 1/200 per unit of blood to 1/10,000,1/10,000,000 [38]. Such a risk did not decline in China until the central government enacted the antiHCV screening in 1993 and outlawed paid blood donations in 1998 [26]. With the risk via transfusion greatly decreased, the risk via injection drug use (IDU) is increasing, which has now become the major risk for contracting HCV infection in China [39]. It has been argued that sexual transmission may also be a major risk for HCV infection especially among male IDUs who have sex with men or with prostitutes [40,41]. In addition, high viral loads has been indicated to increase the risk of HCV vertical and needlestick transmissions [42,43]. Concurrent with a recent transition in the risk from transfusion to IDU, the prevalence of 6a is increasing while 1b is decreasing. As we know, 1b has been regarded to be more associated with HCV transmission via blood transfusion while 6a typically linked to IDU and sexual transmission [12]. In this study, all blood donors were asked to answer a standardized questionnaire before blood donations which listed all the knownrisk factors. Donors would be excluded when having a history of transfusion of blood or blood products, IDU, receiving a tattoo, ear or body piercing, surgery, or other invasive medical procedures. Follow-up studies were also performed on those who were HCV viremic. However, only a small proportion of the donors confessed having these risks (data not shown). It is concerning that subtype 6a might have spread to the general population via the IDU network or through illegal sexual workers. In this regard, a significantly higher proportion of male, found among donors infected with 6a than with other HCV genotypes, is implicative. We found that the percentage of male donors who were HCV viremic is about 3.8 times as many as that of the female donors (79.2 versus 20.8 ), while in initial screening a total of 707 voluntary blood donors were detected to be positive for anti-HCV among whom the male/female ratio is about 2.5 (503/204). It has been reported that women are more likely to clear the virus spontaneously after acute infection [44,45]. This can be interpreted that men are more likely to develop chronic hepatitis than women and continue to be HCV viremic. The interpretation helps to explain why male donors tended to have higher levels of HCV RNA than female donors (6.06 versus 5.69 log 10 IU/ml), which is consistent with the results from a very recent large-scale study based on a multi-ethnic group of IDUs [29]. We firmly believe that the outcomes of HCV infection among women are much better than among men. In support of this belief, there exist additional lines of evidence: 1) HCV is more likely to infect men. In the USA, the prevalence of anti-HCV among men was twice as that among women [4]. In one of our recent studi.