Academic journal article Bulletin of the World Health Organization

Rapid and Simple Hepatitis Assays: Encouraging Results from a Blood Donor Population in Zimbabwe

Academic journal article Bulletin of the World Health Organization

Rapid and Simple Hepatitis Assays: Encouraging Results from a Blood Donor Population in Zimbabwe

Article excerpt

Introduction

Although a large variety of serological assays are available for diagnosing human immunodeficiency virus (HIV) infection (1), there are far fewer assays for detecting hepatitis B virus (HBV) and hepatitis C virus (HCV) infection. An enzyme immunoassay (EIA) is most frequently used to detect HBV surface antigen (HBsAg) and antibodies to HCV. While EIAs are highly accurate and applicable in many situations, alternatives are available and may be more appropriate in some instances; for example, the testing of samples in remote laboratories -- where facilities and capabilities are less than optimal, or a stable electricity supply is not available, and in instances where rapid results are required (emergency transfusions and transplantation services), where low-volume testing is performed, or where technical expertise is limited -- may dictate the need for alternatives such as simple and rapid assays. Use of such assays can be of value in physicians' offices, emergency rooms, autopsy rooms, and in small blood centres.

As technology evolves, tests become simpler and faster, and attractive alternatives to routine methods emerge. For example, oral fluids (3), urine (4), and whole blood (5) have been examined in an effort to simplify collection of samples; their use can result in time and cost savings, and they have proved useful in several situations. The use of rapid and simple tests as alternatives to EIA has also been of value as a confirmatory strategy for HIV testing and can offer cost savings (6). However, new alternatives must be thoroughly evaluated and have comparable accuracy to existing methodologies. The testing of blood for HIV., HBV, and HCV is important, particularly for transfusion purposes.

Recently Constantine et al. reported the successful use of two rapid HCV assays in a highprevalence population in Romania (2); these tests also require to be further evaluated in a low prevalence population. To the best of our knowledge, there have been no other reports on the use of rapid HCV assays. Simple tests to detect HBsAg are available, but accounts of the performance of the new generation of simple tests by independent investigators are scarce. The present article reports the accuracy and performance characteristics of several of these newer rapid hepatitis virus tests in a low prevalence, blood donor population in a developing country.

Materials and methods

Serum samples

A total of 206 serum samples that had been collected routinely as part of the normal services of the National Blood Transfusion Service, Harare, Zimbabwe were used in the study. Of these samples, 196 were freshly collected, while 10 had been stored frozen at 20[degree]C, and were from individuals who had tested reactive for HCV by EIA. These 10 archived sera were included to permit some assessment of the sensitivity of the HCV rapid test since the prevalence of HCV infection in the study population was low (0.4%). In addition, eight of the fresh sera had tested positive for HBsAg on the day prior to the start of the study, and were included for the same reason (the prevalence of HBsAg in the donor population is about 2%).

Testing procedures

All the fresh serum samples, stored at 4[degrees]C, were tested blind using rapid assays within 24 hours of being collected. Testing by EIA (Auszyme (Abbott, Chicago, IL, USA) for HBsAg; and HCV second-generation EIA for HCV (Abbott, Chicago, IL, USA)), was carried out on the previous day and the results were compared with those obtained with the rapid tests. The 10 frozen samples were tested blind along with the fresh samples. The rapid tests included the following: HCV-SPOT (Genelabs Diagnostics, Singapore) for HCV; and SimpliRED HBsAg test (AGEN, Brisbane, Australia) and the Dipstick-HBsAg (Program for Appropriate Technology in Health (PATH), Seattle, WA, USA/Immuno-Chemical Laboratories, Bangkok-RIA) for HBsAg. All tests were performed as recommended by the manufacturers under local laboratory conditions in Harare. …

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