Field evaluation of rapid HIV serologic tests for screening and confirming HIV-1 infection in Honduras

Cost implications of HIV retesting for verification in Africa

INTRODUCTION

HIV misdiagnosis leads to severe individual and public health consequences. Retesting for verification of all HIV-positive cases prior to antiretroviral therapy initiation can reduce HIV misdiagnosis, yet this practice has not been not widely implemented.

METHODS

We evaluated and compared the cost of retesting for verification of HIV seropositivity (retesting) to the cost of antiretroviral treatment (ART) for misdiagnosed cases in the absence of retesting (no retesting), from the perspective of the health care system. We estimated the number of misdiagnosed cases based on a review of misdiagnosis rates, and the number of positives persons needing ART initiation by 2020. We presented the total and per person costs of retesting as compared to no retesting, over a ten-year horizon, across 50 countries in Africa grouped by income level. We conducted univariate sensitivity analysis on all model input parameters, and threshold analysis to evaluate the parameter values where the total costs of retesting and the costs no retesting are equivalent. Cost data were adjusted to 2017 United States Dollars.

RESULTS AND DISCUSSION

The estimated number of misdiagnoses, in the absence of retesting was 156,117, 52,720 and 29,884 for lower-income countries (LICs), lower-middle income countries (LMICs), and upper middle-income countries (UMICs), respectively, totaling 240,463 for Africa. Under the retesting scenario, costs per person initially diagnosed were: $40, $21, and $42, for LICs, LMICs, and UMICs, respectively. When retesting for verification is implemented, the savings in unnecessary ART were $125, $43, and $75 per person initially diagnosed, for LICs, LMICs, and UMICs, respectively. Over the ten-year horizon, the total costs under the retesting scenario, over all country income levels, was $475 million, and was $1.192 billion under the no retesting scenario, representing total estimated savings of $717 million in HIV treatment costs averted.

CONCLUSIONS

Results show that to reduce HIV misdiagnosis, countries in Africa should implement the WHO's recommendation of retesting for verification prior to ART initiation, as part of a comprehensive quality assurance program for HIV testing services.

To err is human, to correct is public health: a systematic review examining poor quality testing and misdiagnosis of HIV status

INTRODUCTION

In accordance with global testing and treatment targets, many countries are seeking ways to reach the "90-90-90" goals, starting with diagnosing 90% of all people with HIV. Quality HIV testing services are needed to enable people with HIV to be diagnosed and linked to treatment as early as possible. It is essential that opportunities to reach people with undiagnosed HIV are not missed, diagnoses are correct and HIV-negative individuals are not inadvertently initiated on life-long treatment. We conducted this systematic review to assess the magnitude of misdiagnosis and to describe poor HIV testing practices using rapid diagnostic tests.

METHODS

We systematically searched peer-reviewed articles, abstracts and grey literature published from 1 January 1990 to 19 April 2017. Studies were included if they used at least two rapid diagnostic tests and reported on HIV misdiagnosis, factors related to potential misdiagnosis or described quality issues and errors related to HIV testing.

RESULTS

Sixty-four studies were included in this review. A small proportion of false positive (median 3.1%, interquartile range (IQR): 0.4-5.2%) and false negative (median: 0.4%, IQR: 0-3.9%) diagnoses were identified. Suboptimal testing strategies were the most common factor in studies reporting misdiagnoses, particularly false positive diagnoses due to using a "tiebreaker" test to resolve discrepant test results. A substantial proportion of false negative diagnoses were related to retesting among people on antiretroviral therapy. Conclusions HIV testing errors and poor practices, particularly those resulting in false positive or false negative diagnoses, do occur but are preventable. Efforts to accelerate HIV diagnosis and linkage to treatment should be complemented by efforts to improve the quality of HIV testing services and strengthen the quality management systems, particularly the use of validated testing algorithms and strategies, retesting people diagnosed with HIV before initiating treatment and providing clear messages to people with HIV on treatment on the risk of a "false negative" test result.

Evaluation of the performances of twelve rapid diagnostic tests for diagnosis of HIV infection in Yaounde, Cameroon

According to the WHO/UNAIDS recommendations, an acceptable HIV rapid diagnostic tests (RDTs) has to perform a sensitivity≥99% and a specificity≥98%. Given the constant release of new RDTs for HIV testing in the market and the high HIV genetic diversity in Cameroon, it is interesting to monitor their performances in that setting. A total of 240 HIV positive (including 219 HIV-1 M, 15 HIV-1 O, 1 HIV-1 N, 1 HIV-1 M/O recombinant and 4 HIV-2) and 240 HIV negative plasma samples were used to evaluate twelve routinely used RDTs in Cameroon. A reference algorithm combining Enzyme Immunoassays and nucleic acid testing was used as gold standard. The sensitivity, specificity, positive predictive value, and negative predictive value of the twelve RDTs evaluated varied between 93.7 and 100%; 95.8 and 100%; 96.0 and 100%, and 94.1 and 100%, respectively. Five out of the twelve RDTs could not detect some HIV-1 O variants, one of them failed to detect an HIV-2 variant while all them efficiently detected HIV-1 N and HIV M/O recombinant. Our findings underscore the need to monitor the performances of RDTs to be used for HIV testing in Cameroon using locally obtained well-characterized samples panels.

Using a Multitest Algorithm to Improve the Positive Predictive Value of Rapid HIV Testing and Linkage to HIV Care in Nonclinical HIV Test Sites

BACKGROUND

Use of a rapid HIV testing algorithm (RTA) in which all tests are conducted within one client appointment could eliminate off-site confirmatory testing and reduce the number of persons not receiving confirmed results.

METHODS

An RTA was implemented in 9 sites in Los Angeles and San Francisco; results of testing at these sites were compared with 23 sites conducting rapid HIV testing with off-site confirmation. RTA clients with reactive results on more than 1 rapid test were considered HIV+ and immediately referred for HIV care. The positive predictive values (PPVs) of a single rapid HIV test and the RTA were calculated compared with laboratory-based confirmatory testing. A Poisson risk regression model was used to assess the effect of RTA on the proportion of HIV+ persons linked to HIV care within 90 days of a reactive rapid test.

RESULTS

The PPV of the RTA was 100% compared with 86.4% for a single rapid test. The time between testing and receipt of RTA results was on average 8 days shorter than laboratory-based confirmatory testing. For risk groups other than men who had sex with men, the RTA increased the probability of being in care within 90 days compared with standard testing practice.

CONCLUSIONS

The RTA increased the PPV of rapid testing to 100%, giving providers, clients, and HIV counselors timely information about a client's HIV-positive serostatus. Use of RTA could reduce loss to follow-up between testing positive and confirmation and increase the proportion of HIV-infected persons receiving HIV care.

Access and Quality of HIV-Related Point-of-Care Diagnostic Testing in Global Health Programs

Access to point-of-care testing (POCT) improves patient care, especially in resource-limited settings where laboratory infrastructure is poor and the bulk of the population lives in rural settings. However, because of challenges in rolling out the technology and weak quality assurance measures, the promise of human immunodeficiency virus (HIV)-related POCT in resource-limited settings has not been fully exploited to improve patient care and impact public health. Because of these challenges, the Joint United Nations Programme on HIV/AIDS (UNAIDS), in partnership with other organizations, recently launched the Diagnostics Access Initiative. Expanding HIV programs, including the "test and treat" strategies and the newly established UNAIDS 90-90-90 targets, will require increased access to reliable and accurate POCT results. In this review, we examine various components that could improve access and uptake of quality-assured POC tests to ensure coverage and public health impact. These components include evaluation, policy, regulation, and innovative approaches to strengthen the quality of POCT.

Why the C-statistic is not informative to evaluate early warning scores and what metrics to use

Metrics typically used to report the performance of an early warning score (EWS), such as the area under the receiver operator characteristic curve or C-statistic, are not useful for pre-implementation analyses. Because physiological deterioration has an extremely low prevalence of 0.02 per patient-day, these metrics can be misleading. We discuss the statistical reasoning behind this statement and present a novel alternative metric more adequate to operationalize an EWS. We suggest that pre-implementation evaluation of EWSs should include at least two metrics: sensitivity; and either the positive predictive value, number needed to evaluate, or estimated rate of alerts. We also argue the importance of reporting each individual cutoff value.

Evaluation of nine HIV rapid test kits to develop a national HIV testing algorithm in Nigeria

Background: Non-cold chain-dependent HIV rapid testing has been adopted in many resource-constrained nations as a strategy for reaching out to populations. HIV rapid test kits (RTKs) have the advantage of ease of use, low operational cost and short turnaround times. Before 2005, different RTKs had been used in Nigeria without formal evaluation. Between 2005 and 2007, a study was conducted to formally evaluate a number of RTKs and construct HIV testing algorithms. Objectives: The objectives of this study were to assess and select HIV RTKs and develop national testing algorithms. Method: Nine RTKs were evaluated using 528 well-characterised plasma samples. These comprised 198 HIV-positive specimens (37.5%) and 330 HIV-negative specimens (62.5%), collected nationally. Sensitivity and specificity were calculated with 95% confidence intervals for all nine RTKs singly and for serial and parallel combinations of six RTKs; and relative costs were estimated. Results: Six of the nine RTKs met the selection criteria, including minimum sensitivity and specificity (both ≥ 99.0%) requirements. There were no significant differences in sensitivities or specificities of RTKs in the serial and parallel algorithms, but the cost of RTKs in parallel algorithms was twice that in serial algorithms. Consequently, three serial algorithms, comprising four test kits (BundiTM, DetermineTM, Stat-Pak® and Uni-GoldTM) with 100.0% sensitivity and 99.1% - 100.0% specificity, were recommended and adopted as national interim testing algorithms in 2007. Conclusion: This evaluation provides the first evidence for reliable combinations of RTKs for HIV testing in Nigeria. However, these RTKs need further evaluation in the field (Phase II) to re-validate their performance.

Performance of rapid HIV testing by lay counselors in the field during the behavioral and biological surveillance survey among female sex workers and men who have sex with men in Botswana

: The study assessed the performance of rapid HIV testing with whole blood using Kehua Bio-engineering HIV (1 + 2) and Uni-Gold HIV test kits by trained and certified lay counselors, offered to female sex workers and men who have sex with men during the 2012 survey fieldwork. The results of rapid HIV testing were compared with enzyme-linked immunosorbent assay testing performed in a parallel algorithm at the HIV Reference Laboratory. The sensitivity and the specificity of rapid HIV testing were high for men who have sex with men and female sex workers, with 98.1% and 100%, and 98.2% and 98.5%, respectively. Misclassifications occurred with rapid testing.

Use of rapid HIV antibody testing for controlling the HIV pandemic

The HIV pandemic continues to expand throughout Africa and southern Asia. Despite recent advances in therapy, the primary means of prevention continues to be the identification of infected patients through diagnostic testing, and the provision of counseling services to reduce HIV transmission. In order to facilitate the identification of infected patients, great strides have been made during the past 10 years towards the development of simple, rapid HIV antibody assays that require no specialized equipment, are relatively stable at ambient temperatures and can be easily performed by people who do not have a laboratory background. Evaluations of these assays have shown that when used in multiple assay algorithm strategies, they perform comparably with current laboratory-based methods. Effective global implementation of these tests will require a concerted effort from public and private health agencies, however, expanding the use of these assays can provide a significant opportunity to slow the devastating spread of HIV.

Rapid tests for detection of viral markers in blood transfusion

Since the early 1990s, rapid tests have been available for detection of HIV infection. They were intended for field diagnosis, emergency and home testing. In addition, rapid tests for anti-HIV, hepatitis B surface antigen and antihepatitis C virus have been used for blood screening in many resource-poor areas to save resources and overcome lack of funding, equipment and electrical supply. The performance of rapid tests varies widely but some have sensitivity and specificity levels that meet standards established by enzyme immunoassays for anti-HIV. Compared with genomic detection of hepatitis B virus, hepatitis B surface antigen rapid tests and enzyme immunoassays have insufficient sensitivity. The clinical consequences of this performance deficit remain to be clarified. Anti-hepatitis C virus rapid tests detect chronically infected individuals who are viremic, however, further studies are required to fully assess their performance. In settings where few blood donations are collected and equipment is unavailable, rapid tests provide a flexible, technically undemanding and relatively inexpensive approach to ensuring a safer blood supply. When utilized for predonation screening in areas of high endemicity of viral markers, rapid tests provide the means to limit blood bag wasting, store only clinically usable blood and inform and counsel deferred donors. As with any laboratory assay, adequate training and sustained quality assurance programs are critical to maintain a safe supply of blood. As a means of achieving a safe blood supply, rapid tests for viral markers and nucleic acid testing have a place next to classic enzyme immunoassays in the definition of strategies that are adapted to a setting's epidemiology, the size and type of donor base, equipment, staff training and resources.

Usefulness of enzyme immunoassay (EIA) for screening of anti HIV antibodies in urinary specimens: A comparative analysis

BACKGROUND

Standard HIV testing is done using serum or plasma. FDA approved ELISA to screen urine for IgG antibodies to HIV-1 in 1996. It is a simple, noninvasive test and is appropriate for developing countries where health care personnel may not be professionally trained or where clean needles for drawing blood may not always be available.

METHODS

436 individuals with high-risk behavior and strong clinical suspicion of HIV infection were screened for IgG antibodies to HIV-1 in urine by ELISA. Urine HIV testing was performed by enzyme immunoassay, at the ongoing Voluntary Confidential Counseling and Testing Center (VCCTC) at a large tertiary care microbiology lab. The individuals enrolled for the study had high-risk exposure to the virus and majorities were from a state with a high incidence of HIV infection. In all individuals, both serum and urine were tested for IgG antibodies to HIV-1.

RESULTS

Overall, 135 individuals (30.96%) were HIV-positive, of whom 96 (71%) had never previously tested positive; 87% of those who tested positive received their results, and most were referred for medical care. Sensitivity, specificity and predictive values of HIV-1 urine ELISA test kit were determined. Sensitivity was found to be 89.6%; 95% CI [82.9-94.0], specificity 97.3%; 95% CI [94.6-98.8], positive predictive value 93.8%; 95% CI [87.8-97.1] and negative predictive value 95.4%; 95% CI [92.3-97.4].

CONCLUSION

Efficiency, sensitivity, and specificity of the urine-based screening for HIV-1 test kits were excellent as compared to the reference test.

Evaluation of HIV/AIDS diagnostics kits and formulation of a testing strategy for Pakistan

BACKGROUND

Rapid diagnosis of HIV/AIDS enables the development of prevention and treatment programmes but accurate, reliable and cost effective testing strategies should be used for testing of HIV/AIDS from a large population.

OBJECTIVE

To evaluate the performance and effectiveness of three assays for the diagnosis of HIV in comparison with Western blot and to formulate an alternative cost-effective confirmatory approach for HIV diagnosis.

STUDY DESIGN

472 specimens (serum) from a Pakistani population were evaluated. Two rapid HIV testing kits (Capillus, SD Bioline) and one ELISA (Vironostika Ag/Ab) kit were used to detect HIV. Results were compared with Western blot against which sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of all HIV assays were assessed.

RESULTS

280/472 (59.3%) of the samples were positive for antibodies against purified HIV-1 viral proteins. The sensitivity of SD Bioline and Vironostika ELISA was 100% (95% CI; 98-100) while that of anti-HIV Capillus™ kit was 94.6% (95% CI; 91-96.8). The specificity of the Vironostika ELISA and anti-HIV Capillus™ kit was 100% (95% CI; 97-100) while specificity of SD Bioline was 98.4% (95% CI; 95-99). PPV was 100% (95% CI; 98-100%) for the anti-HIV Capillus™ and Vironostika ELISA and 98.9% (95% CI; 96-99%) for SD Bioline. NPV for SD Bioline and Vironostika ELISA was 100% (95% CI; 98-100%) and 92.7% for anti-HIV Capillus™ (95% CI; 88-96%).

CONCLUSION

The sensitivity and specificity of all three kits were satisfactory compared to Western blot and could be used for effective diagnosis of HIV/AIDS in Pakistani population.

Potential for false positive HIV test results with the serial rapid HIV testing algorithm

Background

Rapid HIV tests provide same-day results and are widely used in HIV testing programs in areas with limited personnel and laboratory infrastructure. The Uganda Ministry of Health currently recommends the serial rapid testing algorithm with Determine, STAT-PAK, and Uni-Gold for diagnosis of HIV infection. Using this algorithm, individuals who test positive on Determine, negative to STAT-PAK and positive to Uni-Gold are reported as HIV positive. We conducted further testing on this subgroup of samples using qualitative DNA PCR to assess the potential for false positive tests in this situation.

Results

Of the 3388 individuals who were tested, 984 were HIV positive on two consecutive tests, and 29 were considered positive by a tiebreaker (positive on Determine, negative on STAT-PAK, and positive on Uni-Gold). However, when the 29 samples were further tested using qualitative DNA PCR, 14 (48.2%) were HIV negative.

Conclusion

Although this study was not primarily designed to assess the validity of rapid HIV tests and thus only a subset of the samples were retested, the findings show a potential for false positive HIV results in the subset of individuals who test positive when a tiebreaker test is used in serial testing. These findings highlight a need for confirmatory testing for this category of individuals.

Use of a rapid HIV testing algorithm to improve linkage to care

BACKGROUND

Awaiting definitive diagnosis before scheduling healthcare visits complicates HIV screening and referral. Clients screened by rapid tests as initially reactive often fail to return to receive definitive test results, are not linked to care and enter care late or not at all.

OBJECTIVES

To evaluate statewide, (1) the accuracy of a single-visit, two test HIV rapid testing algorithm (RTA) and (2) its effect on referral to care for positive clients.

STUDY DESIGN

A two-test RTA was implemented at 24 sites in New Jersey beginning in December 2008. All clients with a reactive rapid HIV test were offered a second rapid HIV test, and RTA results were compared with Western blot (WB). Referral to care occurred based upon two sequential positive rapid tests.

RESULTS

The RTA program has screened 51,413 individuals obtaining 426 reactive rapid test results; 394 (92.5%) were reactive by a second rapid test, 32 (7.5%) had a negative second rapid test. Twenty-eight individuals refused WB testing. Of 369 RTA-positive individuals who have WB results, 368 (99.5%) were confirmed positive. Of RTA-positive clients, 290 (73.6%), including 25 (6.6%) who refused Western blot, were immediately referred for care including one individual with a false-positive RTA.

CONCLUSIONS

The RTA reduced false positive results by 6.2% and agreed with WB results 99.5% of the time. Improved referral to care compared to traditional rapid HIV screening occurs when immediate referral is based on RTA verification of a preliminary positive rapid test. WB confirmation is not essential for effective screening and contributes to difficulties linking individuals to care.

[Human immunodeficiency virus (HIV) and Hepatitis C virus (HCV) testing among injecting drug users]

In Hungary, there is a need for widely accessible HIV and HCV testing and counseling for injecting drug users. Theoretically, free and confidential rapid HIV and HCV testing would be the most suitable for this purpose. Low threshold agencies, such as needle and syringe programs, would provide ideal premises for such a testing system, Here, participants would be able to undergo regular testing every six months. Making rapid testing widely available raises the following three main issues: 1. validity of the testing results (or: the verification of positive rapid test results), 2. circumstances of taking blood (or: legislation regarding drawing blood), and 3. cost effectiveness (or: how important is it to prevent an HIV epidemic). The authors propose the establishment of a system that offers screening using rapid tests and which would be an expansion of a currently existing system of HIV and HCV testing based on finger prick blood. The current system would thus serve as a means to verify the results of the rapid tests. At the same time, there is a need to obtain permission from a public health body to enable in needle and syringe programs the provision of rapid testing and testing of blood using finger pricks. In many countries, test results are given to injecting drug users not by doctors but by trained social workers - such a system could also be established in Hungary. If preventing an HIV epidemic in Hungary is a priority, then wide access to rapid HIV testing is justified. Widely accessible free and confidential rapid HIV and HCV testing and counseling - combined with screening and verification using finger prick blood - may function not only as a testing and counseling service but also as a good quality public health monitoring system. Such a system, however, requires regular financial support from the government.

Economic evaluation of point-of-care diagnostic technologies for infectious diseases

We review the growing number of economic evaluations of individual point-of-care (POC) tests for diagnosis of infectious diseases in resource-limited settings that use either cohort studies or mathematical models. We focus on studies that evaluate POC diagnostic tests for the control of human immunodeficiency virus (HIV) and malaria, tools that are central to the WHO prevention guidelines for infectious diseases in developing countries. Although rapid diagnostic tests for HIV and malaria seem to be cost-effective in these standard analyses, these do not take into account the reduction in patients' waiting time and the number of clinic visits required to receive results, or future benefits from the reduction in antimalarial drug pressure. Those additional cost reductions would be considerably greater with POC rapid tests, and the cost-effectiveness of POC tests would therefore be improved. Findings from cost-effectiveness analyses suggest that, despite the relatively small additional cost incurred, decision-makers should strongly consider using POC tests throughout or during parts of HIV and malaria epidemics, where this is feasible in terms of local human resources and logistical conditions.

University leadership for innovation in global health and HIV/AIDS diagnostics

Medical products used in the developed world often fail to adequately serve resource-limited settings where electricity, transportation and health care workers are not readily available. We suggest that the problem is not only a lack of coordinated financial resources to purchase existing medical products, but also a lack of products that are specifically designed for resource-limited settings. While donor organisations with a focus on global health are increasingly willing to bear the additional financial risk for the research and development of such high-impact medical products, corporations are still reluctant to take their best scientists and engineers away from more commercially attractive projects. Universities, on the other hand, given their teaching and research missions, are well positioned to engage in such high-risk development projects. A group of biomedical, engineering, business and social science researchers at Northwestern University (NU) propose a creative model to address significant social and health needs. The team's initial product focus is a rapid test for diagnosing infants with HIV. The NU model aligns the incentives and expertise of industry, donors and academia to innovate medical products, such as the infant HIV diagnostic test, for resource-limited settings.

Molecular diagnostics for head and neck pathology

Molecular diagnostic techniques are quickly finding a role in the detection and diagnosis of tumors, and in predicting their behavior. They may also prove useful in developing new therapeutic approaches to head and neck cancer. The surgeon working in the craniomaxillofacial region should have an understanding of these technologies, their availability in various settings, and how they affect various aspects of treatment, particularly in the detection and treatment of malignancies. This article offers an overview of recent advances in molecular diagnostic techniques, with their implications for diagnosis and management of head and neck tumors.

Evaluation of simple rapid HIV assays and development of national rapid HIV test algorithms in Dar es Salaam, Tanzania

BACKGROUND

Suitable algorithms based on a combination of two or more simple rapid HIV assays have been shown to have a diagnostic accuracy comparable to double enzyme-linked immunosorbent assay (ELISA) or double ELISA with Western Blot strategies. The aims of this study were to evaluate the performance of five simple rapid HIV assays using whole blood samples from HIV-infected patients, pregnant women, voluntary counseling and testing attendees and blood donors, and to formulate an alternative confirmatory strategy based on rapid HIV testing algorithms suitable for use in Tanzania.

METHODS

Five rapid HIV assays: Determine HIV-1/2 (Inverness Medical), SD Bioline HIV 1/2 3.0 (Standard Diagnostics Inc.), First Response HIV Card 1-2.0 (PMC Medical India Pvt Ltd), HIV1/2 Stat-Pak Dipstick (Chembio Diagnostic System, Inc) and Uni-Gold HIV-1/2 (Trinity Biotech) were evaluated between June and September 2006 using 1433 whole blood samples from hospital patients, pregnant women, voluntary counseling and testing attendees and blood donors. All samples that were reactive on all or any of the five rapid assays and 10% of non-reactive samples were tested on a confirmatory Inno-Lia HIV I/II immunoblot assay (Immunogenetics).

RESULTS

Three hundred and ninety samples were confirmed HIV-1 antibody positive, while 1043 were HIV negative. The sensitivity at initial testing of Determine, SD Bioline and Uni-Gold was 100% (95% CI; 99.1-100) while First Response and Stat-Pak had sensitivity of 99.5% (95% CI; 98.2-99.9) and 97.7% (95% CI; 95.7-98.9), respectively, which increased to 100% (95% CI; 99.1-100) on repeat testing. The initial specificity of the Uni-Gold assay was 100% (95% CI; 99.6-100) while specificities were 99.6% (95% CI; 99-99.9), 99.4% (95% CI; 98.8-99.7), 99.6% (95% CI; 99-99.9) and 99.8% (95% CI; 99.3-99.9) for Determine, SD Bioline, First Response and Stat-Pak assays, respectively. There was no any sample which was concordantly false positive in Uni-Gold, Determine and SD Bioline assays.

CONCLUSION

An alternative confirmatory HIV testing strategy based on initial testing on either SD Bioline or Determine assays followed by testing of reactive samples on the Determine or SD Bioline gave 100% sensitivity (95% CI; 99.1-100) and 100% specificity (95% CI; 96-99.1) with Uni-Gold as tiebreaker for discordant results.

Improving survey methods in sero-epidemiological studies of injecting drug users: a case example of two cross sectional surveys in Serbia and Montenegro

BACKGROUND

Little is known about the prevalence of HIV or HCV in injecting drug users (IDUs) in Serbia and Montenegro. We measured prevalence of antibodies to HIV (anti-HIV) and hepatitis C virus (anti-HCV), and risk factors for anti-HCV, in community-recruited IDUs in Belgrade and Podgorica, and determined the performance of a parallel rapid HIV testing algorithm.

METHODS

Respondent driven sampling and audio-computer assisted survey interviewing (ACASI) methods were employed. Dried blood spots were collected for unlinked anonymous antibody testing. Belgrade IDUs were offered voluntary confidential rapid HIV testing using a parallel testing algorithm, the performance of which was compared with standard laboratory tests. Predictors of anti-HCV positivity and the diagnostic accuracy of the rapid HIV test algorithm were calculated.

RESULTS

Overall population prevalence of anti-HIV and anti-HCV in IDUs were 3% and 63% respectively in Belgrade (n = 433) and 0% and 22% in Podgorica (n = 328). Around a quarter of IDUs in each city had injected with used needles and syringes in the last four weeks. In both cities anti-HCV positivity was associated with increasing number of years injecting (eg Belgrade adjusted odds ratio (AOR) 5.6 (95% CI 3.2-9.7) and Podgorica AOR 2.5 (1.3-5.1) for >or= 10 years v 0-4 years), daily injecting (Belgrade AOR 1.6 (1.0-2.7), Podgorica AOR 2.1 (1.3-5.1)), and having ever shared used needles/syringes (Belgrade AOR 2.3 (1.0-5.4), Podgorica AOR 1.9 (1.4-2.6)). Half (47%) of Belgrade participants accepted rapid HIV testing, and there was complete concordance between rapid test results and subsequent confirmatory laboratory tests (sensitivity 100% (95%CI 59%-100%), specificity 100% (95%CI 98%-100%)).

CONCLUSION

The combination of community recruitment, ACASI, rapid testing and a linked diagnostic accuracy study provide enhanced methods for conducting blood borne virus sero-prevalence studies in IDUs. The relatively high uptake of rapid testing suggests that introducing this method in community settings could increase the number of people tested in high risk populations. The high prevalence of HCV and relatively high prevalence of injecting risk behaviour indicate that further HIV transmission is likely in IDUs in both cities. Urgent scale up of HIV prevention interventions is needed.

Evaluation of a new hepatitis B virus surface antigen rapid test with improved sensitivity

A new rapid immunochromatographic assay based on the signal amplification system (SAS) has been developed by Diagnostics for the Real World (Europe) Ltd. for the detection of hepatitis B virus surface antigen (HBsAg) in plasma or serum specimens. The SAS format features enhanced sensitivity as a result of an increased binding valence of the detector molecules. We have now evaluated the performance of the new HBsAg rapid test (DRW-HBsAg) in comparison with a well-established commercial rapid test (Determine HBsAg; previously from Abbott Laboratories; now from Inverness Medical Innovations) and with a CE-marked enzyme immunoassay (EIA) (Hepanostika HBsAg Ultra; BioMérieux) as the gold standard. Testing of serially diluted in-house HBsAg-positive samples, the World Health Organization standard, and sensitivity and reference panels yielded an analytical sensitivity for the DRW test of 0.2 to 0.8 IU/ml across HBsAg serotypes. Evaluation with eight commercially available seroconversion panels showed that the DRW-HBsAg test detected HBsAg an average of 6.1 days (range, 3 to 8 days) earlier than the Determine assay (P = 0.0078). Test sensitivity was also examined with two low-titer HBsAg EIA-positive panels in Beijing, China. Whereas 100% of these samples were detected by the DRW-HBsAg test, only 15.0% (P < 0.0001) and 87.3% (P < 0.0001), respectively, were detected by the Determine HBsAg test. The performance of the DRW-HBsAg test was further evaluated with samples determined to be HBsAg positive or negative by the EIA in Conakry, Guinea, and Beijing, China. No significant difference in sensitivity between the DRW and Determine tests was apparent with the HBsAg EIA-reactive samples from Guinea (96.7% versus 94.4%, respectively) or China (99.46 versus 98.92%, respectively). The specificity of the Determine HBsAg test was slightly higher than that of DRW-HBsAg test (100 versus 99.2%, respectively) with samples from EIA-negative blood donors in China. In conclusion, the new DRW HBsAg rapid test is more sensitive than the Determine HBsAg test and is suitable for diagnostic and blood screening in resource-limited settings.

HIV serological screening in a population of pregnant women in the Republic of Congo: suitability of different assays

Different strategies can be applied for the screening of HIV infection, depending on the local seroprevalence. Within a WHO type III strategy, we compared the results of two different second-line methods for HIV screening of a population of pregnant women in the Republic of Congo. Sera from 3614 consecutive pregnant women were tested for HIV with Genescreen Plus Ag/Ab EIA assay; positive specimens were retested with two different second-line methods. (Determine HIV-1/2 rapid test and Vironostika HIV Ag/Ab specific EIA assay). Discordant samples were tested with HIV-1/2 Western Blot and, if necessary, HIV RNA molecular assay. Of the 3614 sera, 221 were positive with Genscreen. Among them, 21 and 10 tested negative with Vironostika and Determine, respectively. A 100% correspondence with 3rd line confirmation test results was found in Genscreen positive/Vironostika negative samples, whereas a 5.5% overestimation of HIV seroprevalence was observed when Determine, instead of Vironostika, was used as second-line test. The choice of appropriate assays in adequate sequence, within the correct WHO strategy, is pivotal to minimize the risk of overtreatment of HIV infection.

Alternative algorithms for human immunodeficiency virus infection diagnosis using tests that are licensed in the United States

Serodiagnosis of human immunodeficiency virus (HIV) infection in the United States has traditionally relied on a sequential two-test algorithm: an initial screen with an enzyme immunoassay (EIA) and reflex testing of EIA-reactive specimens with a more specific supplemental test such as Western blotting or immunofluorescence. The supplemental tests are tedious, subjective, and expensive. In addition, there have been major improvements in the performance and accuracy of the EIA tests as well as the introduction of rapid serologic tests (RT) and HIV nucleic acid amplification tests (NAAT). Related to these improvements is the possibility that alternative algorithms using combinations of currently approved HIV tests may function as well as if not better than the current algorithm, with more flexibility, improved accuracy, and lower cost. To this end, we evaluated the performance of 12 currently licensed tests and 1 in-house HIV test (6 EIA, 4 RT, and 3 NAAT) on panels of plasma samples from HIV-infected (n = 621 HIV type 1 [HIV-1] and 34 HIV-2) and uninfected (n = 513) people and of sequential specimens from people early in seroconversion (183 specimens from 15 patients). Test combinations were analyzed in two dual-test (sensitivity-optimized and specificity-optimized) algorithms and in a three-test (tie-breaking) algorithm, and performance was compared to the conventional algorithm. The results indicate that alternative algorithm strategies with currently licensed tests compare favorably with the conventional algorithm in detecting and confirming established HIV infection. Furthermore, there was a lower frequency of discordant or indeterminate results that require follow-up testing, and there was improved detection of early infection.

Sexual risk behaviors for HIV/AIDS in Chuuk State, Micronesia: the case for HIV prevention in vulnerable remote populations

BACKGROUND

After the first two cases of locally-acquired HIV infection were recognized in Chuuk State, Federated States of Micronesia (FSM), a public health response was initiated. The purpose of the response was to assess the need for HIV education and prevention services, to develop recommendations for controlling further spread of HIV in Chuuk, and to initiate some of the prevention measures.

METHODOLOGY/PRINCIPAL FINDINGS

A public health team conducted a survey and rapid HIV testing among a sample of residents on the outer islands in Chuuk. Local public health officials conducted contact tracing and testing of sex partners of the two locally-acquired cases of HIV infection. A total of 333 persons completed the survey. The majority knew that HIV is transmitted through unprotected sexual contact (81%), injection drug use (61%), or blood transfusion (64%). Sexual activity in the past 12 months was reported among 159 participants, including 90 females and 69 males. Compared to women, men were more likely to have had multiple sex partners, to have been drunk during sex, but less likely to have used a condom in the past 12 months. The two men with locally acquired HIV infection had unprotected anal sex with a third Chuukese man who likely contracted HIV while outside of Chuuk. All 370 persons who received voluntary, confidential HIV counseling and testing had HIV negative test results.

CONCLUSIONS/SIGNIFICANCE

Despite the low HIV seroprevalence, risky sexual behaviors in this small isolated population raise concerns about the potential for rapid spread of HIV. The lack of knowledge about risks, along with stigmatizing attitudes towards persons infected with HIV and high risk sexual behaviors indicate the need for resources to be directed toward HIV prevention in Chuuk and on other Pacific Islands.

Evaluation and implementation of rapid HIV tests: the experience in 11 African countries

Rapid HIV testing enables HIV prevention and care services to expand to settings with limited laboratory infrastructure. The World Health Organization recommends that prior to their implementation, rapid HIV tests first be evaluated at a reference laboratory and then at points-of-service, and that measures to ensure quality of testing be in place. We describe the experience of 11 African countries that implemented rapid HIV testing using this process. A questionnaire regarding rapid test evaluations and quality assurance measures was administered to personnel in ministries of health, reference laboratories, and Centers for Disease Control and Prevention programs in 11 African countries. In reference laboratory evaluations, median sensitivity was above 99% for 10 of 15 rapid tests and median specificity was above 99% for 13 of 15 rapid tests. Similar results were observed in evaluations at point-of-service sites. Rapid testing algorithms have been implemented in over 600 sites in nine of the countries. Concordance between point-of-service rapid testing and reference laboratory retesting of samples ranged from 95.7% to 99.5% (median: 98.7%). A systematic approach to the evaluation and implementation of rapid HIV tests was useful in ensuring accurate, decentralized testing even when conducted by persons with limited laboratory experience.

Post-evaluation of rapid HIV kits in the Korean market by an anti-HIV EQAS panel

This study aimed to provide evaluation information about rapid HIV kits by the anti-HIV External Quality Assessment Schemes (EQAS) panel of the Korea National Institute of Health (KNIH) and the rapid HIV test panel of the US Centers for Disease Control and Prevention (CDC). Each KNIH anti-HIV EQAS panel from 2003 to 2005 consisted of four or five samples of plasma obtained from blood donors with a strong positive or negative reaction to HIV. KNIH delivered each panel to public health centers for analysis of the HIV test results, and the reactivity of the five rapid HIV kits currently used in the Korean market were compared with that of a CDC reference. The analytic sensitivity and specificity of the rapid HIV kits for the KNIH anti-HIV EQAS in 2005 were 99.3 and 99.1%, respectively; in 2004, 98.8 and 97.1%; and in 2003, 94.8 and 95.9%. Five HIV kits from the CDC panel consistently showed positive reactivity for strong positive samples in all kits, but some showed erratic reactivity for weakly positive samples. This is the first report on post-evaluation of rapid HIV kits in the Korean market by an anti-HIV EQAS panel. It was found that the quality of performance of the rapid HIV tests had improved each year but should be interpreted with caution for weakly positive samples.

A synthetic gag p24 epitope chemically coupled to BSA through a decaalanine peptide enhances HIV type 1 serodiagnostic ability by several folds

p24 is an immunodominant gag core protein of HIV-1. The synthetic immunodominant epitope of p24 and the recombinant p24 show poor immunoreactivity and specificity, respectively. Their application is, therefore, severely limited in the serodiagnosis of HIV-1, although it is an important marker for early diagnosis. These limitations have been overcome by conjugating the synthetic p24 to BSA through a decaalanine peptide spacer. The engineered p24 shows about 5-fold more efficient immunoreactivity than the synthetic p24, and, at the same time, shows a several fold reduction in nonspecific cross-reactivity as compared to recombinant p24. Our strategy to conjugate the p24 peptide epitope to BSA worked well as a consistent and reliable immunodiagnostic marker. This strategy may also prove useful for the diagnosis of other diseases.

Rapid HIV testing: a review of the literature and implications for the clinician

HIV counseling and testing services are critical for individuals to access HIV prevention and treatment. Unfortunately, the standard HIV testing algorithm is complex and includes the use of a sensitive enzyme immunoassay (EIA), followed by a Western blot if the EIA is positive. This process can take 1 week or longer. Therefore, innovative approaches that incorporate simpler diagnostic algorithms are needed to reach the large number of individuals who are not aware that they are HIV-infected. Currently available rapid HIV tests have demonstrated sensitivities and specificities comparable to those of standard HIV testing without the requirements of sophisticated laboratory resources or highly trained personnel. These rapid HIV tests are increasingly being used in various clinical scenarios to decrease the number of missed opportunities for detection of HIV-infection. Their use is particularly applicable in specific clinical and nonclinical settings; public health settings; labor and delivery wards; in the management of occupational exposures; and in resource-constrained settings. The overarching goals of achieving wide implementation of rapid HIV tests are to increase the number of individuals who are aware of their serostatus, to improve entry of persons with HIV into prevention and care services, and to prevent further HIV transmission.

Diagnosis of pediatric human immunodeficiency virus infection in resource-constrained settings

The majority of children infected with human immunodeficiency virus live in resource-constrained settings and die without an established diagnosis. Definitive laboratory diagnosis in children younger than 12-18 months requires virologic testing; however, antibody testing is often the only option available. Antibody testing provides a definitive diagnosis in older children but is frequently not used. Children meeting clinical criteria should be treated regardless of availability of laboratory diagnoses.

Evaluation of rapid tests for anti-HIV detection in Brazil

OBJECTIVES

This assessment in Brazil was to evaluate the performance of commercially available HIV rapid test (RT) against the gold standard testing and to establish a highly sensitive and specific RT algorithm for HIV diagnosis.

DESIGN

A prospective, anonymous and unlinked study.

METHODS

An evaluation of seven commercially available RT to compare their performance against the gold standard tests for Brazil. This includes two competing enzyme immunoassays plus a Western blot for confirmation. After informed consent, whole blood samples were collected from volunteers in voluntary counselling and testing sites (n = 400), antenatal clinics (n = 500) and from HIV-positive controls in AIDS treatment centres (n = 200). Two seroconversion panels, one HIV-1 subtype (B, B', C and F) panel and an operational assay performance evaluation were also part of the study parameters.

RESULTS

For the seven RT the clinical sensitivity ranged from 97.74 to 100% and clinical specificity from 99.43 to 100%. However, only four RT were considered acceptable after full evaluation. The two EIA had a clinical sensitivity of 100% and clinical specificity of 99.32 and 99.66%. Two RT had the same performance on the seroconversions panels as the EIA. The operational assay performance evaluation for the RT indicated that Hexagon and Capillus could not be classified as simple assays.

CONCLUSION

We have provided evidence that RT assays can perform equally or better than EIA for the detection of HIV antibodies. The simplicity and rapidity of the RT warrants its utilization in an algorithm for a rapid diagnosis of HIV infection.

Evaluation of rapid prenatal human immunodeficiency virus testing in rural cameroon

Pregnant women (n = 859) in rural Cameroonian prenatal clinics were screened by two rapid human immunodeficiency virus (HIV) antibody tests (rapid tests [RT]) (Determine and Hema-Strip) using either whole blood or plasma. One additional RT (Capillus, HIV-CHEK, or Sero-Card) was used to resolve discordant results. RT results were compared with HIV-1 enzyme immunoassay (EIA) and Western blot (WB) results of matched dried blood spots (DBS) to assess the accuracy of HIV RTs. DBS EIA/WB identified 83 HIV antibody-reactive, 763 HIV antibody-nonreactive, and 13 indeterminate specimens. RT results were evaluated in serial (two consecutive tests) or parallel (two simultaneous tests) testing algorithms. A serial algorithm using Determine and Hema-Strip yielded sensitivity and specificity results of 97.6% and 99.7%, respectively, whereas a parallel RT algorithm using Determine plus a second RT produced a sensitivity and specificity of 100% and 99.7%, respectively. HIV RTs provide excellent alternatives for identifying HIV infection, and their field performance could be monitored using DBS testing strategies.

Rapid HIV testing. Wait time reduced from days to minutes

Recent breakthroughs in technology have produced tests for HIV antibody that are highly accurate and easy to use and can give a preliminary result in 20 minutes or less. These rapid HIV tests will be used increasingly in labor and delivery wards, emergency departments, urgent care centers, and the primary care office. They have unique applications for healthcare worker exposures, military operations, public health venues, and developing countries. In this article, Drs Keenan, Keenan, and Branson discuss the advantages and limitations of rapid HIV testing in various settings.

Use of rapid and conventional testing technologies for human immunodeficiency virus type 1 serologic screening in a rural Kenyan reference laboratory

We report a prospective comparison of human immunodeficiency virus type 1 testing by enzyme immunoassay and Western blot with four rapid tests of 486 subjects performed in rural Kenya. Rapid test sensitivity was 100%. Specificity ranged from 99.1 to 100%. Combined use of two Food and Drug Administration-approved rapid tests yielded a single false-positive result.

Field evaluation of a rapid human immunodeficiency virus (HIV) serial serologic testing algorithm for diagnosis and differentiation of HIV type 1 (HIV-1), HIV-2, and dual HIV-1-HIV-2 infections in West African pregnant women

We evaluated a two-rapid-test serial algorithm using the Determine and Genie II rapid assays, performed on-site in four peripheral laboratories during the French Agence Nationale de Recherches sur le SIDA (ANRS) 1201/1202 Ditrame Plus cohort developed for prevention of mother-to-child transmission of human immunodeficiency virus (HIV) infection in Côte d'Ivoire. A total of 1,039 specimens were retested by two commercial enzyme-linked immunosorbent assays (ELISAs). The following specimens were tested: 315 specimens found on-site to be infected with HIV type 1 (HIV-1), 8 specimens found on-site to be infected with HIV-2, 71 specimens found on-site to be infected with both HIV-1 and HIV-2, 40 specimens found on-site to have indeterminate results for HIV infection, and 605 specimens taken during a quality assurance program. For HIV discrimination, 99 positive serum samples (20 with HIV-1, 8 with HIV-2, and 71 with HIV-1 and HIV-2 on the basis of our rapid test algorithm) were retested by the Peptilav test, Western blot (WB) assays, and homemade monospecific ELISAs. Real-time DNA PCRs for the detection of HIV-1 and HIV-2 were performed with peripheral blood mononuclear cells from 35 women diagnosed on-site with HIV-1 and HIV-2 infections. Compared to the results of the ELISAs, the sensitivities of the Determine and Genie II assays were 100% (95% lower limit [95% LL], 99.1%) and 99.5% (95% confidence interval [95% CI], 98.2 to 99.9%), respectively. The specificities were 98.4% (95% CI, 96.9 to 99.3%) and 100% (95% LL, 99.3%), respectively. All serological assays gave concordant results for infections with single types. By contrast, for samples found to be infected with dual HIV types by the Genie II assay, dual reactivity was detected for only 37 samples (52.1%) by WB assays, 34 samples (47.9%) by the Peptilav assay, and 23 samples (32.4%) by the monospecific ELISAs. For specimens with dual reactivity by the Genie II assay, the rates of concordance between the real-time PCR assays and the serological assays were 25.7% for the Genie II assay, 82.9% for the Peptilav assay, 74.3% for WB assays, and 80% for the homemade ELISAs. Our algorithm provided high degrees of sensitivity and specificity comparable to those of ELISAs. Even if they are rare, women identified by the Genie II assay as being infected with HIV-1 and HIV-2 mostly appeared to be infected only with HIV-2.

Cost comparison of three HIV counseling and testing technologies

BACKGROUND

In the United States, more than 2 million human immunodeficiency virus (HIV) antibody tests are performed annually at publicly funded HIV counseling and testing (CT) clinics. Clients do not receive results from one third of these tests because of low return rates. New rapid-testing technologies may improve receipt of results, but no study has systematically analyzed the costs of these newer technologies compared with the standard protocol.

OBJECTIVE

To estimate and compare the economic costs associated with three HIV CT protocols: the standard protocol and the one-step and two-step rapid protocols.

METHODS

A cost analysis model was developed in 2002 to calculate the intervention costs for HIV CT services with the standard CT protocol and the one-step and two-step rapid-test protocols for a hypothetical client in a publicly funded HIV clinic. Sensitivity analyses were performed to ascertain the effects of uncertainty in the model parameters.

RESULTS

The one-step rapid protocol was generally the least expensive of the three protocols. The standard protocol cost less than the two-step protocol per HIV-positive client notified of his or her HIV status, but cost more per HIV-negative client. The sensitivity analysis indicated overlap in the cost estimates for HIV-negative clients, reflecting the generally similar costs of the three testing protocols. Taking into account HIV seroprevalence, the two-step rapid protocol would be less expensive than the standard protocol for most publicly funded testing programs in the United States.

CONCLUSIONS

Rapid test protocols offer economic advantages as well as convenience, compared to the standard testing protocol. The cost estimates presented here should prove helpful to HIV program managers and other public health decision makers who need information on these counseling and testing technologies.

Prenatal testing for infectious disease

Prenatal testing for infectious diseases is performed frequently and for a variety of indications. The purpose of this article is to review the maternal and fetal infections that pose diagnostic concerns. Recent advances in diagnostic testing (such as avidity testing) is included. Testing issues focus on the diagnosis of maternal and fetal infection.

HIV-1 infection in injection drug users

Injection drug use is an efficient and ongoing means of HIV transmission and is the principal mode of transmission in some parts of the world. In the United States, approximately 10,000 injection drug users are believed to acquire HIV each year. The US Public Health Service hopes to decrease all HIV transmission in the United States by 50% in the next 5 years, by promoting care and prevention services to infected persons. Subtle differences in the virology and immunopathogenesis of HIV between injection drug users and other groups at risk are still being investigated. So far such differences have no practical implication. Comparison of progression rates and survival with HIV across risk groups has been difficult because of the many competing causes of death unrelated to HIV among injection drug users, but overall HIV disease progression rates are similar across risk groups, after adjusting for age. Some AIDS-related opportunistic infections are more common (such as tuberculosis) or less common (such as Kaposi's sarcoma) among injection drug users, based on rates of exposure and latent infection. Other comorbidities, including chronic psychiatric disorders and hepatitis C disease, are more common among injection drug users than among others with HIV infection. Highly active antiretroviral treatment seems to be as effective in persons with a history of injected drug use as in others. Increasing the numbers of HIV-infected injection drug users who know their diagnosis, increasing their access to care and prevention services, and increasing their adherence to a therapeutic regimen are the current challenges in confronting the HIV-epidemic among injection drug users. To overcome these obstacles, clinicians must have both technical knowledge and skill in assisting patients with behavior change.

Rapid confirmation of HIV infection

OBJECTIVE

To investigate the utility of a prototype rapid confirmatory HIV assay which offers specific results in 5 min and has applications in a variety of important testing situations.

METHODS

The performance of the rapid confirmatory assay was assessed with 849 blood samples, including serum, plasma, venipuncture whole blood, and peripheral blood collected via fingerstick. Included were over 700 HIV Western blot (WB)-confirmed antibody positive sera, and others which were classified as negative or indeterminate by WB. The analytic sensitivity of the rapid confirmatory assay was assessed using 13 HIV-1 seroconversion panels, and all results were compared to those of an FDA-licensed WB reference test.

RESULTS

The rapid test exhibited 100% concordance with the reference test when testing HIV-1 WB-confirmed positive samples, and 92.3% concordance with samples having WB-inconclusive results. The sensitivity for confirming recent seroconversion was as good, or better than, the FDA-licensed HIV-1 WB in 10/13 panels. The rapid assay performed accurately with whole blood collected from fingerstick, and exhibited excellent precision and reproducibility.

CONCLUSION

We conclude that this rapid HIV confirmatory assay, the first of its kind, demonstrates proof of principle for the accurate confirmation of HIV-1 infection and offers important advantages in public health and clinical testing venues.

Evaluation of an alternative confirmatory strategy for the diagnosis of HIV infection in Dar Es Salaam, Tanzania, based on simple rapid assays

Alternative confirmatory strategies for detection of antibodies to HIV using enzyme-linked immunosorbent assays (ELISAs) have been shown to be useful in laboratories with limited resources. Three simple and rapid HIV antibody detection assays (Capillus, Serocard and Determine) were evaluated using 1412 fresh serum samples in order to formulate an alternative confirmatory strategy for the diagnosis of HIV infection. All sera were also tested by an anti-HIV ELISA and all sera reactive by any of the assays were tested by a second ELISA as well as by Western blot. Three hundred and eighty-three sera were found to be HIV-1 antibody positive, while 1017 sera were HIV antibody negative; 12 sera which were reactive by one or more of the simple assays had indeterminate Western blot results and these were considered HIV seronegative during the analysis. All assays had a sensitivity of 100%. The initial specificity of the assays were 98.7, 98.2 and 97.9% for Capillus, Serocard and Determine, respectively. In an alternative confirmatory strategy the use of Capillus followed by Serocard or Determine gave a specificity of 99.9 and 99.8%, respectively. Serocard followed by Determine gave a specificity of 99.3%. A testing strategy with 100% specificity (95% CI; 99.6-100%) could be achieved by the sequential use of all three simple/rapid assays or by repeat testing by Capillus followed by Serocard.

The Serostatus Approach to Fighting the HIV Epidemic: prevention strategies for infected individuals

In the United States, HIV prevention programs have historically tailored activities for specific groups primarily on the basis of behavioral risk factors and demographic characteristics. Through the Serostatus Approach to Fighting the Epidemic (SAFE), the Centers for Disease Control and Prevention is now expanding prevention programs, especially for individuals with HIV, to reduce the risk of transmission as a supplement to current programs that primarily focus on reducing the risk of acquisition of the virus. For individuals with HIV, SAFE comprises action steps that focus on diagnosing all HIV-infected persons, linking them to appropriate high-quality care and prevention services, helping them adhere to treatment regimens, and supporting them in adopting and sustaining HIV risk reduction behavior. SAFE couple a traditional infectious disease control focus on the infected person with behavioral interventions that have been standard for HIV prevention programs.

Laboratory testing and rapid HIV assays: applications for HIV surveillance in hard-to-reach populations

Most HIV surveillance has been performed through serologic surveys in relatively stable, accessible populations. Similar surveillance, with or without counseling and testing, in populations that are hard-to-reach, presents logistical challenges, including the selection of laboratory testing strategy and algorithm. The advent of rapid serologic assays for HIV now allows for on-site testing, including confirmatory testing, and rapid provision of test results and counseling. The possibility of only a single contact makes repeat sampling, which current diagnostic testing recommendations include, difficult. To address the logistical complexities in surveillance in hard-to-reach populations and the increased availability of rapid tests, we propose adapting the testing strategies for HIV of the World Health Organization/the joint United Nations Programme on HIV/AIDS in order to facilitate this surveillance, including, where carried out, the provision of test results back to individuals. The choice of enzyme-linked immunosorbent assay (ELISA) versus rapid testing for these settings is discussed, as is the choice of specimen--blood, oral fluid, or urine. Three appendices summarize: (1) test algorithms for the various testing strategies; (2) advantages and disadvantages of ELISA and of rapid test formats, and (3) the characteristics and status of currently available rapid HIV tests. We also discuss the potential application of the recently developed 'detuned' methodology for estimating HIV incidence in hard-to-reach populations.