|Statistics underline need for more rapid HIV testing|
|By Sebastian Thaler|
|Monday, 27 June 2011 05:22|
As the U.S. marks National HIV Testing Day today (June 27), recent statistics underline the urgent need for more rapid HIV testing. Fewer than half of Americans have had an AIDS test since guidelines were expanded to include routine screening, according to a CDC report last November. A clinical trial whose results were released in May reported that patients with HIV were 96 percent less likely to transmit the infection to their sexual partners if they were taking antiretroviral drugs. Also, many states with the most serious HIV epidemics are home to large numbers of infected people who go undiagnosed, according to a USA TODAY analysis of CDC data.
Rapid testing technology can ensure a more timely diagnosis for those with HIV. Once an HIV test has proven positive, getting a patient on early treatment reduces AIDS-related deaths by 50 to 60 percent and improves the health and quality of life of thousands of people living with HIV. Early treatment has also proved capable of lowering viral levels and the potential for HIV transmission to others.
Healthcare facilities currently employ a range of standard screening tests for antibodies to HIV. Immunoassays are a key element in the diagnosis of various medical conditions, including HIV. The market for professional point-of-care (POC) immunoassays is estimated at $1.625 billion; with 14% growth, this market segment will reach $2.77 billion in 2012. These include the enzyme immunoassay (EIA or ELISA), which requires two visits to a clinic or medical facility: one for the patient to receive pretest counseling and to have blood drawn for HIV testing, and the second for them to receive test results and additional counseling (and, if needed, referrals).
In contrast to traditional tests, a new generation of rapid HIV tests can produce results within 20 minutes or less and allow testing, counseling and referrals to be accomplished in a single visit to a healthcare provider. These rapid tests are less costly for testing agencies to perform due to the decreased number of outreach visits required to deliver results. Also, studies have shown that rapid tests are just as sensitive and specific as conventional immunoassays. The tests can be safely stored at room temperature for up to 24 months before being used, making them ideal for the over-the-counter market as viable HIV tests to be self-administered by individuals at home.
Chembio’s DPP® technology has enabled the development of POC assays that offer unique features and capabilities, including improved control in working with challenging sample types, such as oral fluid. Tests that the company has developed to date using DPP® include an oral fluid HIV 1/2 test and a five-band point-of-care confirmatory test for HIV ½; both are already approved in Brazil, with the confirmatory test recently being featured in Brazilian media as the Company reported last week.
Chembio’s DPP® HIV 1/2 Screen Assay is a single-use, rapid screening test that utilizes immobilized antigens for the detection of antibodies to HIV types 1 and 2 in oral fluid, fingerstick whole blood, venous whole blood, serum, or plasma samples. It employs a unique combination of a specific antibody binding protein, which is conjugated to colloidal gold dye particles, and HIV 1/2 antigens, which are bound to the membrane solid phase.
DPP® technology incorporates a number of advantages over lateral flow technology, which is widely employed in home pregnancy tests. DPP® offers significantly increased sensitivity in comparative studies; In these studies the DPP® HIV rapid test results showed sensitivity ranging from 10 to 50 times that of lateral flow.
The speed as well as the sensitivity of DPP® assays are enhanced due to the improved membrane clearance that results from better uniformity and consistency of conjugate particles that migrate without the sample particles. In particular, DPP® is able to effectively resolve common aggregation issues that are present in lateral flow assays with large particle analytes such as bacteria. With DPP®, the bacterial samples, after filtering, are applied directly to the test site and immobilized while the marker conjugate is free to migrate without the sample to the test zone.
In addition, DPP® allows enhanced multiplexing—the ability to simultaneously measure dozens (or more) of analytes in a single assay—with independent and simultaneous delivery of samples. The technology provides multiple analyte results with a high degree of sensitivity without compromising specificity due to cross-reactivity, an issue common in lateral flow tests. Furthermore, DPP® is able to run tests on different types of body fluids, including blood, serum, oral fluids, sputum, urine, or feces, all while maintaining a high level of sensitivity.
Given the urgent need for improved sensitivity, the use of different bodily fluid sample types, and the desirability of testing for multiple analytes in one device, it is anticipated that DPP® and other new technologies may lead to a new generation of rapid HIV testing options.