Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 28, Num. 3, 2010, pp. 264-265

Indian Journal of Medical Microbiology, Vol. 28, No. 3, July-September, 2010, pp. 264-265

Correspondence

RNA positivity rates among anti-HCV reactive blood donors in Sri Lanka: A preliminary study

A Manamperi¹, P Nugawela², NS Gunawardene¹, Wimaladharma Abeyewickreme¹, J de Silva¹

¹ Molecular Medicine Unit, Department of Medicine, Faculty of Medicine, University of Kelaniya, Thalagolla Road, Ragama, Sri Lanka
² National Blood Centre, Narahenpita, Sri Lanka
Correspondence Address: A Manamperi, Molecular Medicine Unit, Department of Medicine, Faculty of Medicine, University of Kelaniya, Thalagolla Road, Ragama, Sri Lanka
areshamanamperi@gmail.com

Date of Submission: 03-Dec-2009
Date of Acceptance: 05-Apr-2010

Code Number: mb10081

PMID: 20644323
DOI: 10.4103/0255-0857.66475

Dear Editor,

The practice of screening donors for hepatitis C virus antibodies (anti-HCV) can substantially lower the risk of transmitting HCV infection via a transfusion. However, detection of hepatitis C specific molecular markers in blood is the most reliable means of diagnosing active viral infection. Blood transfusion services in many developed countries in the West have introduced nucleic acid amplification technology (NAT) to screen blood donations, most commonly for hepatitis C viral RNA (HCV RNA). ^[1],[2] In most of these cases, the implementation of NAT has been through blood mini-pool testing and is primarily intended for detection of the viraemia that precedes the development of antibodies during the initial phase of infection. Qualitative detection of HCV RNA is also used in the diagnosis of active infection, especially in immunocompromised patients and in individuals with indeterminate serology results. ^[2] Further, quantification of viral RNA is also useful in evaluating the course of clinical disease and assessing the effectiveness of antiviral therapy. ^[2]

In 2003, the Blood Transfusion Service of Sri Lanka implemented the screening of donors for anti-HCV using a third-generation ELISA (enzyme-linked immunosorbent assay; Ortho HCV 3.0, Ortho Clinical Diagnostics, NJ, USA). The present work was carried out as a preliminary project to evaluate the RNA positivity among the anti-HCV-positive blood donors to assess the feasibility of applying NAT for HCV RNA at the initial donor screening stage in our transfusion setting. Eighty-nine anti-HCV reactive donors were tested for the presence of HCV RNA by reverse transcription-polymerase chain reaction (RT-PCR). The 89 serology-positive donors were initially detected using ELISA by routine screening of an initial pool of 26176 blood donors. RNA was extracted using QIAmp viral RNA mini columns (Qiagen Corp., 27220 Turnberry Lane, Valencia, CA 91355, USA) according to the manufacturer′s instructions. A one-step RT-PCR kit (Access Quick RT-PCR system, Cat. No. A1702 - Promega, USA) was utilized for detection of HCV RNA in individual donor samples. A 246-base pair fragment of the 5′ untranslated region (5′ UTR) of the viral genome was amplified by RT-PCR, using oligonucleotide primers RC1 and RC21 ^[3] (Integrated DNA Technologies, 1710 Commercial Park, Coralville, IA 52241, USA). Of the 89 anti-HCV reactive donors (26176 of the total donor pool), 6 (0.023% of the total donor pool, and 6.74% of the antibody-positive individuals) were positive for HCV RNA, indicating a low prevalence of HCV-RNA-positive donors in this cohort of blood donors. This is in keeping with the low prevalence of HCV infection in the community, which is less than 1% according to general population studies carried out using serological markers. ^[4],[5] The RNA-negative, anti-HCV-positive profiles are either false-positive serology results or represent donors who have been exposed to HCV previously and whose infections have subsequently resolved. We applied NAT testing to individual anti-HCV-antibody-positive blood donations as this approach offers substantial advantages with regard to sensitivity, specificity, donor identification, and confirmatory testing. The cost of introducing NAT for HCV screening was calculated to be about USD 20 per test. Since the prevalence of HCV is low in Sri Lanka, and the window period associated with this screening method is unknown, routine individual HCV-RNA testing to detect donors in the window period cannot be justified as a cost-effective measure, though RNA testing for mini-pools could be considered. We propose that NAT be implemented only for anti-HCV reactive samples and that too only so that those with active viral replication can be offered treatment.

References

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