The current incidence, prevalence, and residual risk of hepatitis B viral infections among voluntary blood donors in China.

BACKGROUND: There are few data available on the prevalence, incidence, and residual risk of transfusion-transmitted HBV (TT-HBV) infections among Chinese blood donors. This study investigated the demographic characteristics of blood donors, as well as the prevalence, incidence, and residual risk (RR) of TT-HBV infections in six large blood centers in different regions of China. METHODS: The demographic characteristics and HBV screening test results of blood donors from six blood centers in different regions in China were collected and analyzed. The hepatitis B surface antigen (HBsAg) yield approach was used to estimate the incidence of HBV. Then, the RR of TT-HBV infections was evaluated using the incidence-window period model. RESULTS: The majority of donors were between 18 and 35 years old (including 35), with the exception of the Changzhi Blood Center where a majority of donors were between 35 and 55 years old (including 55). The prevalences of HBV were 0.13%, 0.078%, 0.16%, 0.07%, 0.20%, 0.25% in Hefei, Dalian, Changzhi, Kaifeng, Mianyang and Fujian, respectively. The estimated corresponding incidences were 213.44, 161.59, 989.80, 278.05, 125.31 and 352.19 per 105 person-years. Using an infectious window period of 59 days, the RR for HBV was estimated to be 34.14, 25.85, 158.35, 44.48, 20.04 and 56.35 per 105 person-years in Hefei, Dalian, Changzhi, Kaifeng, Mianyang and Fujian, respectively. CONCLUSION: Despite the introduction of more sensitive assays in blood screening, our data revealed that the current residual risk of TT-HBV infection was still high (overall 56.53 per 105 py). A continuous monitoring of the residual risk of transfusion-transmitted infections is crucial for safe blood management.

Establishing a reentry procedure for human immunodeficiency virus screening-reactive donors in China.

BACKGROUND: Screening of blood donors for antibody to human immunodeficiency virus Types 1 and 2 (anti-HIV-1/2) and/or HIV nucleic acid test (NAT) is a well-established venue to prevent HIV transfusion-transmitted disease. However, with the current available technologies, HIV testing may result in donor loss due to false-positive results. This study intended to establish a donor reentry procedure for HIV screening-reactive donors in China. STUDY DESIGN AND METHODS: From September 1, 2013, to August 31, 2014, a total of 465 donors from 14 Chinese blood centers were enrolled in this study. Enrollment criteria include all donors who were screened reactive or belonged to the "gray zone" by enzyme-linked immunosorbent assay and/or reactive by NAT when tested at the local blood centers. All donor samples were sent to a central HIV confirmation laboratory where anti-HIV-1/2 and HIV individual-donation NATs were conducted. If the results were reactive for anti-HIV-1/2, then the samples were tested with a recombinant immunoblot assay. RESULTS: Based on the repeat testing at the central HIV confirmation laboratory 8 or 16 weeks after the study, 252 donors of 465 (54.2%) who completed the study could be classified in two categories for HIV status: 45 (18%) true positive and 207 (82%) false positive. A total of 213 of 465 (45.8%) donors were lost on follow-up and, thus, their HIV status cannot be determined with certainty. Based on these data, a donor reentry procedure was proposed. CONCLUSION: Based on our proposed donor reentry procedure for HIV screening-reactive donors, a majority of screening-positive donors (82%, 207/252) can be reentered safely.

[Study on the method of recognizing abandoned farmlands based on multispectral remote sensing].

Being abandoned for farmland seriously affected China's grain output for farmlands. It has become an important phenomenon over the past 20 years in China. Multispectral remote sensing has the advantage of wide range and high speed in requiring data. It has great potential in the research on land use. Therefore, to extract abandoned farmland in China, the authors' used the NDVI data of Modis/Terra from 2000 to 2009 which is one of multispectral remote sensing data and the Remote Sensing Image of ALOS satellite in Japan. The authors' used the parameter of NDVI of time series to describe the character of the main land use types. After drawing the time-series curves of the main land use type samples, the authors' analyzed them with consulting the life character of these types. Then, the authors' compared these curves; finally we recognized abandoned farmland from the others. At last the authors' went to experimental plot to survey the land use. The results demonstrated that the method of using multispectral remote sensing data can abstract abandoned farmland and classify the main kind of land use, and the accuracy is as high as 90%. So the method is feasible in recognizing abandoned farmland.