China is facing critical challenges in blood availability and safety. Although the volume of blood collected for transfusion has constantly increased at a rate of 8% per year in China (Figure 1), the blood supply has not kept pace with the clinical demand, so China faces consistent seasonal blood shortage [14]. Despite the successful shift from paid and employer-organized donations to voluntary donations in recent years, the emerging HIV epidemic, the growing syphilis epidemic and the high HBV and HCV prevalence in the general population [7–10] are still considered serious blood safety problems in China. To ensure blood safety, it is critical to monitor ongoing epidemiological information, not only from high-risk groups, but also from individuals from the general population such as volunteer blood donors. The donor demographic characteristics of these four blood centers are quite different from the donor profile of many Western countries. For example, 60% of donors were male, half were under age 25, most donors in Guangzhou were single, and 60% of donations were from first-time donors (Table 2). To ensure an adequate blood supply, it is critical to recruit suitable blood donors. In China, the recruiting strategies to encourage the current 60% of first-time donors to return for regular donation are very important to compensate for the blood shortage.
As the number of HIV cases continues to grow in China, transfusion-transmissible HIV infection poses an increasing threat to blood safety. By the end of August 2010, there were 361,599 overall reported HIV positives, including 127,203 AIDS cases and 65,104 recorded deaths [15]. The Chinese CDC report estimated that for people living with HIV(about 650,000) by the end of 2005 in China, about 10.7% of all HIV infections in China [16] were infected by receiving blood or blood products (approximately totaling 69,550 cases). The majority of these cases were infected in late 1980’ and early 1990’ as a result of illegal plasma and whole blood collection practices[17]. The Blood Donation Law published in 1998 and the closing down of illegal plasma and whole blood collection operations by the government have greatly reduced the cases of transfusion transmitted HIV infections in China after 1998 but there is no official published data on the actual cases since 2005. One study stated that the prevalence rate of HIV infection was about 0.085% among donors from Zhejiang Province, with a growing frequency from 1:600,000 in 1995 to 1:37,500 in 2004[18]. Another meta-analysis indicated the prevalence and trend of HIV infection among voluntary blood donors in China since implementation of the Blood Donation Law (1998) [19]. This report demonstrated that an overall 2573 HIV positive cases were identified among voluntary blood donors between 2000 and 2009 in twenty-nine provinces with a prevalence of 13.33/100 000 and the overall prevalence increasing steadily and quickly. In the present work, the results demonstrated a declining trend of HIV prevalence between 2000 and 2002, and exhibited a mild fluctuation with a slightly increasing trend in later years (Table 3). Our results showed varying HIV prevalence rates among different regions in China, Liaoning (0.22%) and Yancheng (0.18%) displayed four to ten times higher HIV prevalence among blood donors than Guangzhou (0.02%) and Nanjing (0.08%).
Since the nationwide HBV vaccination program was implemented in 1992, the prevalence of HBsAg in the Chinese population has dropped to 7.2%, but China still has high HBV prevalence, with approximately 100 million individuals with chronic HBV [8]. Due to pre-donation HBsAg rapid testing, the prevalence of HBsAg (0.86%) was much lower in the donor population than that in the general population. Furthermore, present data also indicated a significant reduction in HBsAg contamination in the blood supply over the 11-year study period despite varying by blood center, such as in Guangzhou, where there is a demonstrated steady prevalent trend (Table 3). Similar decline has been reported in developed and developing countries [20–23]. The seroprevalence of HBV was significantly higher among donors who were in the higher age groups, male, less educated, employed, married or first-time donors, as compared to those who were among the lower age groups, female, more educated, students, single or repeated donors, respectively (Table 4).
Since the Blood Donation Law was enacted in 1998, the prevalence of HCV infection has been reduced dramatically in the general population. Two reasons may contribute to the significantly higher prevalence in blood donors than that in the general population before the Blood Donation Law was enacted. Firstly, before 1998, due to paid blood donations, blood centers pooled and centrifuged the blood; they retained the plasma and re-infused donors with red blood cells from the pool, which enabled people to sell their plasma more frequently without developing anemia. Secondly, this may reflect a significant testing bias and perhaps inaccessibility of anti-HCV testing among the general population, which might attract a higher proportion of high-risk persons to donate blood for the purpose of determining their infection status. However, the prevalence of HCV infection slumped dramatically to 1.71% after 1998 [9]. As presented in Table 3, the prevalence of HCV in China was significantly lower than it had been before 1998, with distinguishable differences among various regions. From 2000 to 2006, the prevalence rate showed a significant decreasing trend. After 2006, the rate started to increase probably due to a widespread HCV epidemic. Previous data have shown a high prevalence rate of HBV and HCV in China, and both viruses share several common infectious routes. Both viruses displayed a significant decline among blood donors over the study period. This decline may imply a decline in HBV and HCV in the segment of the population recruited to donate; a continuing increase in the proportion of the population that has been diagnosed with both viruses; or improved effectiveness of education and screening processes, resulting in the deferral of persons reporting high-risk behaviors. As previously discussed, lower prevalence rates for HBV (0.86%) and HCV (0.51%) were detected in blood donors than in the general population. This difference implies that predonation screening and/or self-selection of blood donors is effective.
China has experienced a dramatic resurgence of syphilis during the last two decades. Since sexually transmitted disease (STD) studies in China have reported syphilis prevalence to be about 10 times higher than HIV prevalence in both high-risk and low-risk populations, it is considered the most pressing public health issues[24]. One study also suggested there was a significant growth in syphilis serologic markers among first-time donors, with 0.41%, 0.45%, and 0.57% positivity from 2008 to 2010[13]. Our data indicated the complicated prevalence of syphilis during the study periods. As indicated in Table 3, Yancheng and Nanjing displayed a relatively constant high level of syphilis prevalence over the period; Guangzhou exhibited a continually growth trend from 0.21% in 2000 to 0.66% in 2010; and Liaoning demonstrated a continually decreasing trend from 1.00% in 2000 to 0.47% in 2010. Higher prevalence rates were also associated with donors who were older than 25 years, less educated, married, employed, or first-time donors (Table 4). The overall prevalence rate was high although the data varied among different regions, time and characteristic donors. Low education level, high age, marriage, employment and first-time donation should be the risk factors for syphilis infection.
Before 1998, TTIs were very common in China due to contaminated blood collection, particularly in for-profit plasma collection facilities. To eliminate this risk, the Chinese government has implemented many strategies, including banning paid blood donations and recruiting certain employer-organized and volunteer donations among low-risk populations [25]. The government has also implemented more sensitive screen reagents and different screening strategies. In recent years, the proportion of volunteer donors has rapidly increased, from 5% in 1998 to 71.5% at the end of 2004 and to 99% at 2011. They now constitute the main source of the blood supply in all major blood banks in China [26].
There are some limitations of this study. Firstly, we did not do confirmatory tests using widely accepted assays to perform further testing on these pathogens reactive and inconclusive donations. The prevalence of these pathogens in blood donors could be over-evaluated, potentially affecting our findings about both donor blood-borne pathogen prevalence and the relative prevalence of these pathogens between donors and the general population. Secondly, we have not analyzed these donors TTIs prevalence in a way to estimate the TTIs residual risk. Thirdly, not all centers used the same kits during the study period, and the assays varied among four blood centers, also weakening the conclusions about the regional differences in prevalence.
In the present study, we investigated the overall prevalence of various TTIs in blood donors giving blood at four regional Chinese blood centers from 2000 to 2010. The overall prevalence rates for HIV, HBV, HCV and syphilis were 0.08%, 0.86%, 0.51% and 0.47%, respectively. The seroprevalence of TTIs appears to be substantially lower among blood donors than in the general population of China, because of successful screening and the selection of donors who are at a lower risk for infection. Although the risk of TTI has been reduced dramatically, the majority of Chinese blood centers currently still rely on serology tests, with no NAT testing for routine donor screening. A few studies have demonstrated a relatively high residual risk compared to developed countries [27–30]. Fortunately, the government has realized the importance of NAT testing. In 2011, NAT testing on HBV, HCV, and HIV was piloted in eleven selected blood centers. It will be implemented at all provincial-level blood centers in the next several years. The population prevalence of TTIs which potentially threaten the safety of the blood supply, along with rising transfusion demands for blood, have stimulated an increased awareness of the importance of strengthening the safety of the blood supply and blood transfusion in China. We believe the residual risk of TTIs will be greatly reduced after NAT implementation.
