HIV testing near the patient: changing the face of HIV testing

Laboratory evaluation of the Chembio Dual Path Platform HIV-Syphilis Assay

Background

Use of rapid diagnostic tests for HIV and syphilis has increased remarkably in the last decade. As new rapid diagnostic tests become available, there is a continuous need to assess their performance and operational characteristics prior to use in clinical settings.

Objectives

In this study, we evaluated the performance of the Chembio Dual Path Platform (DPP^®) HIV–Syphilis Assay to accurately diagnose HIV, syphilis, and HIV/syphilis co-infection.

Method

In 2013, 990 serum samples from the Georgia Public Health Laboratory in Atlanta, Georgia, United States were characterised for HIV and syphilis and used to evaluate the platform. HIV reference testing combined third-generation Enzyme Immunoassay and Western Blot, whereas reference testing for syphilis was conducted by the Treponema pallidum passive particle agglutination method and the TrepSure assay. We assessed the sensitivity and specificity of the DPP assay on this panel by comparing results with the HIV and syphilis reference testing algorithms.

Results

For HIV, sensitivity was 99.8% and specificity was 98.4%; for syphilis, sensitivity was 98.8% and specificity was 99.4%. Of the 348 co-infected sera, 344 (98.9%) were detected accurately by the DPP assay, but 11 specimens had false-positive results (9 HIV and 2 syphilis) due to weak reactivity.

Conclusion

In this evaluation, the Chembio DPP HIV–Syphilis Assay had high sensitivity and specificity for detecting both HIV and treponemal antibodies. Our results indicate that this assay could have a significant impact on the simultaneous screening of HIV and syphilis using a single test device for high-risk populations or pregnant women needing timely care and treatment.

The evaluation of accuracy of serial rapid HIV test algorithm in the diagnosis of HIV antibodies among pregnant women in south east Nigeria

Background

Accurate HIV testing in pregnancy is critical to the prevention of mother to child transmission of HIV infection and linkages to other preventive strategies.

Aims and objectives

This study determined the sensitivity, specificity negative and positive predictive value of serial rapid testing of HIV among pregnant women in Nnewi, south east Nigeria.

Methodology

This was a comparative descriptive study conducted over a 4-month period. Serial rapid testing algorithm was compared with conventional ELISA testing after obtaining informed consents from the pregnant women. All positive and discordant results were confirmed with western blot HIV test. Participants also completed a questionnaire. Data analysis was done using SPSS version 20.

Result

A total of 166 pregnant women participated in this study. The mean age of the participants was 29 ± 4.3 years. The HIV prevalence was highest in the 25–29 years category. This was also the modal age category. Majority of the women were multiparous. The prevalence of HIV infection was 12 %. The sensitivity, specificity, negative and positive predictive value of serial rapid HIV testing was 95, 100, 99.3 and 100 % respectively.

Conclusion

The sensitivity of the serial rapid test algorithm was high but still lower than the WHO recommended 99 % and above. The 100 % specificity and positive predictive value makes it a good diagnostic test strategy. There is need for regular review of HIV test kits and policy.

Feasibility and Field Performance of a Simultaneous Syphilis and HIV Point-of-Care Test Based Screening Strategy in at Risk Populations in Edmonton, Canada

Few studies have evaluated the feasibility of delivering syphilis point-of-care (POC) testing in outreach (nonclinical) settings in resource rich countries. The objectives of the study were to evaluate the feasibility and diagnostic performance of performing both HIV and syphilis POC testing in outreach settings and to document new cases identified in the study population. 1,265 outreach testing visits were offered syphilis and HIV POC testing and 81.5% (n = 1,031) consented to testing. In our population, the SD Bioline 3.0 Syphilis Test had a sensitivity of 85.3% [CI (68.9-95.0)], specificity of 100.0% [CI (99.6-100.0)], positive predictive value (PPV) of 100.0% [CI (88.1-100.0)], and negative predictive value (NPV) of 99.5% [CI (98.9-99.8)]. Test characteristics for the INSTI HIV-1/HIV-2 Antibody Test had a 100.0% sensitivity [CI (39.8-100.00], 99.8 specificity [CI (99.3-100)], 66.7% PPV [CI (22.3-95.7)], and 100.0% NPV [CI (99.6-100.0)]. Four new cases of syphilis and four new HIV cases were diagnosed. In summary, at risk population seeking STI testing found POC tests to be acceptable, the POC tests performed well in outreach settings, and new cases of syphilis and HIV were identified and linked to treatment and care.

The INSTI HIV-1/HIV-2 antibody test: a review

INTRODUCTION

Rapid HIV tests have been widely adopted globally as an important component of HIV prevention and control programs. The INSTI™ HIV-1/HIV-2 antibody test is a second-generation HIV antibody test, available in most countries for use from whole blood, serum, and plasma.

AREAS COVERED

Available data on kit characteristics and current performance data on the INSTI™ HIV-1/HIV-2 antibody test are presented together with six other rapid point-of-care tests (RPOCTs) for HIV antibody. Few published data are available providing direct comparisons of INSTI™ with other RPOCTs for HIV antibody and standard laboratory-based HIV-1/HIV-2 antibody assays. Existing data showed that INSTI™ has comparable performance to other RPOCTs but detected seroconversion later than standard laboratory-based assays.

EXPERT OPINION

The good performance of INSTI HIV-1/HIV-2 antibody test, its ease of use, the rapid availability of results (< 5 min), and the lack of specialized equipment required to use the kit make this kit a useful addition to the global market. The unique antigen and flow through technology contained in the kit make it a strong addition to HIV RPOCTs and to rapid/rapid algorithms used in many resource-limited settings.

Past, present and future molecular diagnosis and characterization of human immunodeficiency virus infections

Substantive and significant advances have been made in the last two decades in the characterization of human immunodeficiency virus (HIV) infections using molecular techniques. These advances include the use of real-time measurements, isothermal amplification, the inclusion of internal quality assurance protocols, device miniaturization and the automation of specimen processing. The result has been a significant increase in the availability of results to a high level of accuracy and quality. Molecular assays are currently widely used for diagnostics, antiretroviral monitoring and drug resistance characterization in developed countries. Simple and cost-effective point-of-care versions are also being vigorously developed with the eventual goal of providing timely healthcare services to patients residing in remote areas and those in resource-constrained countries. In this review, we discuss the evolution of these molecular technologies, not only in the context of the virus, but also in the context of tests focused on human genomics and transcriptomics.

Diagnosing infections--current and anticipated technologies for point-of-care diagnostics and home-based testing

In recent years, we have witnessed many transitions in healthcare systems around the globe. For example, population expansion and ageing, and the human immunodeficiency virus (HIV)-AIDS epidemics, have exerted pressure to decentralize the practice of healthcare outside of traditional settings to bring care to those in need. Upstream of patient management, diagnosis is aimed at adequately orienting medical decisions, and considerable efforts have been made to make this process faster and more efficient. However, there are several diseases and medical conditions that may/will benefit from technologies and tests that can be performed closer to the patient, at the point of care or even in the home. In this review, and in light of the paradox that technology and assay developers and healthcare officials must take into consideration for advancing human health in developed and developing countries, we present an overview of rapid diagnosis of infectious diseases at the point of care and of technologies that may contribute to enhancement of the worldwide point-of-care testing market.