Thailand Study Affirms Value of Nucleic Acid Testing in Developing World
Chaing Mai, Thailand - A study recently conducted by researchers from Chiron and Chiang Mai University Hospital in Thailand highlighted the value of using the PROCLEIX® ULTRIO® Assay in the conditions most common throughout rural Asia.
Chiang Mai Hospital currently uses only serologic testing for routine screening of blood donations for HIV, hepatitis C (HCV) and hepatitis B (HBV) viruses. Because nucleic acid testing (NAT) measures the genetic components of viral particles in blood samples instead of antibodies, it is able to detect the presence of infectious agents in blood sooner than immunoassays.
By using the PROCLEIX ULTRIO Assay, the study's researchers were seeking to determine if the donor population in Chang Mai, Thailand could benefit from the use of nucleic acid testing for blood screening. Investigators tested 5,083 samples using both the hospital's current immunoassay testing and the PROCLEIX ULTRIO Assay and found that 17 of the samples tested showed a discrepancy between the two test methods. While the study did not turn up HIV-1- or HCV-positive donations that tested negative with immunoassays, the ULTRIO Assay did detect six HBV-tainted blood donations that immunoassay testing was not able to detect, thus preventing these donations from entering the blood supply.
The study was particularly interesting because it examined the use of ULTRIO in a smaller, hospital-based blood bank in rural Asia, which is most characteristic of blood donation in the region. "Although there was no HIV-1 and HCV yield, suggesting that the health history screening process was effective in reducing the risk to those pathogens, there was approximately 1 HBV positive per 800 donations with nucleic acid testing, which would have been missed by conventional immuno testing," said Dr. Andrew Heaton, Chief Scientific Officer for Chiron. "This study confirms the considerable remaining risk to blood recipients even after immuno testing and affirms the need for ULTRIO testing of blood donations."
The HBV yield was also significant because chronic HBV infection rates are significantly higher in Southeast Asia than in other parts of the world. The CDC estimates that the rate of chronic HBV infection in the general population in Southeast Asia, as well as all of Africa and much of the Middle East, is greater than eight percent. By contrast, the prevalence of chronic HBV infection is less than two percent in the general population in Western Europe and North America.
As in Chiang Mai, many Asian, African, and Eastern European facilities currently use only serologic tests in routine blood screening. For technological and economic reasons, NAT assays have not been widely used for routine donor screening in developing countries, despite the high prevalence rate of HBV infection. While it is not yet feasible to replace some immunological testing with NAT screening in much of the developing world, the Thailand study indicates that NAT implementation - as a supplement to serologic screening - would deliver a significant increase in safety to the blood supply.
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This article is based on the summary Evaluation of a Multiplex HIV-1, Hepatitis C and Hepatitis B Virus NAT Assay to Detect Viremic Blood Donors in Northern Thailand by Niwes Nantachit, Lakkana Thaikruea, Satawat Thongsawat, Nipapan Leetrakool, Ladda Fongsatikul, Prakai Sompan, Yiu-Lian Fong, David Nichols, Rainer Ziermann, Paul Ness, and Kenrad E. Nelson, Transfusion, in press.