Borrelia burgdorferi was discovered to be the cause of Lyme disease in 1983, leading to seroassays. The 1994 serodiagnostic testing guidelines predated a full understanding of key B. burgdorferi antigens and have a number of shortcomings. These serologic tests cannot distinguish active infection, past infection, or reinfection. Reliable direct-detection methods for active B. burgdorferi infection have been lacking in the past but are needed and appear achievable. New approaches have effectively been applied to other emerging infections and show promise in direct detection of B. burgdorferi infections.

The cause of Lyme disease, Borrelia burgdorferi, was discovered in 1983. A 2-tiered testing protocol was established for serodiagnosis in 1994, involving an enzyme immunoassay (EIA) or indirect fluorescence antibody, followed (if reactive) by immunoglobulin M and immunoglobulin G Western immunoblots. These assays were prepared from whole-cell cultured B. burgdorferi, lacking key in vivo expressed antigens and expressing antigens that can bind non-Borrelia antibodies. Additional drawbacks, particular to the Western immunoblot component, include low sensitivity in early infection, technical complexity, and subjective interpretation when scored by visual examination. Nevertheless, 2-tiered testing with immunoblotting remains the benchmark for evaluation of new methods or approaches. Next-generation serologic assays, prepared with recombinant proteins or synthetic peptides, and alternative testing protocols, can now overcome or circumvent many of these past drawbacks. This article describes next-generation serodiagnostic testing for Lyme disease, focusing on methods that are currently available or near-at-hand.

Background: HIV testing is critical for both HIV treatment and prevention. Expanding testing in hospital settings can identify undiagnosed HIV infections. Methods: To evaluate the feasibility of universally offering HIV testing during emergency department (ED) visits and inpatient admissions, 9 hospitals in the Bronx, New York and 7 in Washington DC undertook various efforts to encourage staff to offer HIV testing routinely. Outcomes included the percentage of encounters with an HIV test, the change from year 1 to year 3, and the percentages of tests that were HIV-positive and new diagnoses. Results: From February 1, 2011 to January 31, 2014, HIV tests were conducted during 6.5% of 1,621,016 ED visits and 13.0% of 361,745 inpatient admissions in Bronx hospitals and 13.8% of 729,172 ED visits and 22.0% of 150,655 inpatient admissions in DC, with wide variation by hospital. From year 1 to year 3, testing was stable in the Bronx (6.6% to 6.9% of ED visits, 13.0% to 13.6% of inpatient admissions), but increased in DC (11.9% to 15.8% of ED visits, 19.0% to 23.9% of inpatient admissions). Overall, in the Bronx 0.4% (408) of ED HIV tests were positive, 0.3% (277) were new diagnoses; 1.8% (828) of inpatient tests were positive, 0.5% (244) were new diagnoses. In DC, 0.6% (618) of ED tests were positive, 0.4% (404) were new diagnoses; 4.9% (1349) of inpatient HIV tests were positive, 0.7% (189) were new diagnoses. Conclusion: Hospitals consistently identified previously undiagnosed HIV infections, but universal offer of HIV testing proved elusive.

OBJECTIVE: The HIV Prevention Trials Network (HPTN) 065 trial sought to expand HIV screening of emergency department (ED) patients in Bronx, New York, and Washington, D.C. This study assessed the testing costs associated with different expansion processes and compared them with costs of a hypothetical optimized process. METHODS: Micro-costing studies were conducted in two participating EDs in each city that switched from point-of-care (POC) to rapid-result laboratory testing. In three EDs, laboratory HIV testing was only conducted for patients having blood drawn for clinical reasons; in the other ED, all HIV testing was conducted with laboratory testing. Costs were estimated through direct observation and interviews to document process flows, time estimates, and labor and materials costs. A hypothetical optimized process flow used minimum time estimates for each process step. National wage and fringe rates and local reagent costs were used to determine the average cost (excluding overhead) per completed nonreactive and reactive test in 2013 U.S. dollars. RESULTS: Laboratory HIV testing costs in the EDs ranged from $17.00 to $23.83 per completed nonreactive test, and POC testing costs ranged from $17.64 to $37.60; cost per completed reactive test ranged from $89.29 to $123.17. Costs of hypothetical optimized HIV testing with automated process steps were approximately 45% lower for nonreactive tests and 20% lower for reactive tests. The cost per ED visit to conduct expanded HIV testing in each hospital ranged from $1.21 to $3.96. CONCLUSION: An optimized process could achieve additional cost savings but would require an investment in electronic system interfaces to further automate testing processes.

OBJECTIVE: To assess HIV testing and factors associated with receipt of testing among persons with Medicaid and commercial insurance during 2012. METHODS: Outpatient and laboratory claims were analyzed from two databases: all Medicaid claims from six states and all claims from Medicaid health plans from four other states and a large national convenience sample of patients with commercial insurance in the United States. We excluded those aged <13 years and >64 years, enrolled <9 of the 12 months, pregnant females, and previously diagnosed with HIV. We identified patients with new HIV diagnoses that followed (did not precede) the HIV test, using HIV ICD-9 codes. HIV testing percentages were assessed by patient demographics and other tests or diagnoses that occurred during the same visit. RESULTS: During 2012, 89,242 of 2,069,536 patients (4.3%) with Medicaid had at least one HIV test, and 850 (1.0%) of those tested received a new HIV diagnosis. Among 27,206,804 patients with commercial insurance, 757,646 (2.8%) had at least one HIV test, and 5,884 (0.8%) of those tested received a new HIV diagnosis. During visits that included an HIV test, 80.2% of Medicaid and 83.0% of commercial insurance claims also included a test or diagnosis for a sexually transmitted infection (STI), and/or Hepatitis B or C virus at the same visit. CONCLUSIONS: HIV testing primarily took place concurrently with screening or diagnoses for STIs or Hepatitis B or C. We found little evidence to suggest routine screening for HIV infection was widespread.

OBJECTIVE: In 2011, the National Health Interview Survey (NHIS), an in-person household interview, revised the human immunodeficiency virus (HIV) section of the survey and the Behavioral Risk Factor Surveillance System (BRFSS), a telephone-based survey, added cellphone numbers to its sampling frame. We sought to determine how these changes might affect assessment of HIV testing trends. METHODS: We used linear regression with pairwise contrasts with 2003-2013 data from NHIS and BRFSS to compare percentages of persons aged 18-64 years who reported HIV testing in landline versus cellphone-only households before and after 2011, when NHIS revised its in-person questionnaire and BRFSS added cellphone numbers to its telephone-based sample. RESULTS: In NHIS, the percentage of persons in cellphone-only households increased 13-fold from 2003 to 2013. The percentage ever tested for HIV was 6%-10% higher among persons in cellphone-only than landline households. The percentage ever tested for HIV increased significantly from 40.2% in 2003 to 45.0% in 2010, but was significantly lower in 2011 (40.6%) and 2012 (39.7%). In BRFSS, the percentage ever tested decreased significantly from 45.9% in 2003 to 40.2% in 2010, but increased to 42.9% in 2011 and 43.5% in 2013. CONCLUSIONS: HIV testing estimates were lower after NHIS questionnaire changes but higher after BRFSS methodology changes. Data before and after 2011 are not comparable, complicating assessment of trends.

Data from a 2006 telephone survey representative of New York City adults showed that more than half (56.2%) of those aged 18 to 64 years responded favorably to a question about acceptability of a rapid home HIV test. More than two thirds of certain subpopulations at high risk for HIV reported that they would use a rapid home HIV test, but approximately half who expressed interest had indications of financial hardship. The match of acceptability and HIV risk bodes well for self-testing utility, but cost might impede uptake.

Approximately 16% of the estimated 1.1 million persons living with human immunodeficiency virus (HIV) in the United States are unaware of their infection and thus unable to benefit from effective treatment that improves health and reduces transmission risk. Since 2006, CDC has recommended that health-care providers screen for HIV all patients aged 13-64 years unless prevalence of undiagnosed HIV infection in their patients has been documented to be <0.1%. This report describes novel HIV screening programs at the Urban Health Plan (UHP), Inc. in New York City and the Interim Louisiana Hospital (ILH) in New Orleans. Data were provided by the two programs. UHP screened a monthly average of 986 patients for HIV during January 2011-September 2013. Of the 32,534 patients screened, 148 (0.45%) tested HIV-positive, of whom 147 (99%) received their test result and 43 (29%) were newly diagnosed. None of the 148 patients with HIV infection were previously receiving medical care, and 120 (81%) were linked to HIV medical care. The ILH emergency department (ED) and the urgent-care center (UCC) screened a monthly average of 1,323 patients from mid-March to December 2013. Of the 12,568 patients screened, 102 (0.81%) tested HIV-positive, of whom 100 (98%) received their test result, 77 (75%) were newly diagnosed, and five (5%) had acute HIV infection. Linkage to HIV medical care was successful for 67 (74%) of 91 patients not already in care. Routine HIV screening identified patients with new and previously diagnosed HIV infection and facilitated their linkage to medical care. The two HIV screening programs highlighted in this report can serve as models that could be adapted by other health-care settings.

In the United States, of the 1.1 million persons infected with human immunodeficiency virus (HIV) and the 2.7 million infected with hepatitis C virus (HCV), approximately 16% and 50%, respectively, are unaware of their infection. Highly effective treatments have turned both diseases into manageable conditions, and in the case of hepatitis C, a disease that can be cured. Early diagnosis is imperative so infected persons can take measures to stay healthy, get into care, benefit from therapy, and reduce the risk of transmission. In this report, we review current recommendations provided by the Centers for Disease Control and Prevention (CDC) and the United States Preventive Services Task Force on whom to screen for HIV and HCV infections, and recommendations from the CDC, the Association of Public Health Laboratories, and the Clinical and Laboratory Standards Institute on how to test for these infections.

BACKGROUND: Point-of-care (POC) rapid HIV tests have sensitivity during the "window period" comparable only to earliest generation EIAs. To date, it is unclear whether any POC test performs significantly better than others. OBJECTIVE: Compare abilities of POC tests to detect early infection in real time. STUDY DESIGN: Men who have sex with men (MSM) were recruited into a prospective, cross-sectional study at two HIV testing sites and a research clinic. Procedures compared four POC tests: one performed on oral fluids and three on fingerstick whole blood specimens. Specimens from participants with negative POC results were tested by EIA and pooled nucleic acid amplification testing (NAAT). McNemar's exact tests compared numbers of HIV-infected participants detected. RESULTS: Between February 2010 and May 2013, 104 men tested HIV-positive during 2479 visits. Eighty-two participants had concordant reactive POC results, 3 participants had concordant non-reactive POC tests but reactive EIAs, and 8 participants had acute infection. Of 12 participants with discordant POC results, OraQuick ADVANCE Rapid HIV-1/2 Antibody Test performed on oral fluids identified fewer infections than OraQuick performed on fingerstick (p=.005), Uni-Gold Recombigen HIV test (p=.01), and determine HIV-1/2 Ag/Ab combo (p=.005). CONCLUSIONS: These data confirm that oral fluid POC testing detects fewer infections than other methods and is best reserved for circumstances precluding fingerstick or venipuncture. Regardless of specimen type, POC tests failed to identify many HIV-infected MSM in Seattle. In populations with high HIV incidence, the currently approved POC antibody tests are inadequate unless supplemented with p24 antigen tests or NAAT.

BACKGROUND: An alternative HIV testing algorithm, designed to improve the detection of acute and early infections and differentiate between HIV-1 and HIV-2 antibodies, has been developed by the Centers for Disease Control and Prevention and the Association of Public Health Laboratories. While it promises greater sensitivity, it also raises concerns about costs. OBJECTIVE: We sought to compare the most commonly used algorithm which was developed in 1989, a third-generation (3G) immunoassay (IA) and Western blot confirmatory test, to a newer algorithm. The new algorithm includes either a 3G or a fourth-generation (4G) initial IA, followed by confirmatory testing with a HIV-1/HIV-2 differentiation IA and, if needed, a nucleic acid amplification test (NAT). STUDY DESIGN: We conducted an analysis of HIV testing costs from the perspective of the laboratory, and classified costs according to IA testing volume. We developed a decision analytic model, populated with cost data from 17 laboratories and published assay performance data, to compare the cost-effectiveness of the testing algorithms for a cohort of 30,000 specimens with a 1% HIV prevalence and 0.1% acute HIV infection prevalence. RESULTS: Costs were lower in high-volume laboratories regardless of testing algorithm. For specimens confirmed positive for HIV antibody, the alternative algorithm (IA, Multispot) was less costly than the current algorithm (IA, WB); however, there was wide variation in reported testing costs. For our cohort, the alternative algorithm initiated with a 3G IA and 4G IA identified 15 and 25 more HIV infections, respectively, than the 1989 algorithm. In medium-volume laboratories, the 1989 algorithm was more costly and less effective than the alternative algorithm with a 3G IA; in high-volume laboratories, the alternative algorithm with 3G IA costs $162 more per infection detected. The alternative algorithm with 4G instead of 3G incurred an additional cost of $14,400 and $4865 in medium- and high-volume labs, respectively. DISCUSSION: HIV testing costs varied with IA testing volumes. The additional cost of 4G over 3G IA might be justified by the additional cases of HIV detected and transmissions averted due to earlier detection. CONCLUSION: The alternative HIV testing algorithm compares favorably to the 1989 algorithm in terms of cost and effectiveness.

BACKGROUND: The use of Western blot (WB) as a supplemental test after reactive sensitive initial assays can lead to inconclusive or misclassified HIV test results, delaying diagnosis. OBJECTIVE: To determine the proportion of specimens reactive by immunoassay (IA) but indeterminate or negative by WB that could be resolved by alternative supplemental tests recommended under a new HIV diagnostic testing algorithm. STUDY DESIGN: Remnant HIV diagnostic specimens that were reactive on 3rd generation HIV-1/2 IA and either negative or indeterminate by HIV-1 WB from 11 health departments were tested with the Bio-Rad Multispot HIV-1/HIV-2 Rapid Test (Multispot) and the Gen-Probe APTIMA HIV-1 RNA Qualitative Assay (APTIMA). RESULTS: According to the new testing algorithm, 512 (89.8%) specimens were HIV-negative, 55 (9.6%) were HIV-1 positive (including 19 [3.3%] that were acute HIV-1 and 9 [1.6%] that were positive for HIV-1 by Multispot but APTIMA-negative), 2 (0.4%) were HIV-2 positive, and 1 (0.2%) was HIV-positive, type undifferentiated. 47 (21.4%) of the 220 WB-indeterminate and 8 (2.3%) of the 350 WB-negative specimens were HIV-1 positive. CONCLUSION: Applying the new HIV diagnostic algorithm retrospectively to WB-negative and indeterminate specimens, the HIV infection status could be established for nearly all of the specimens. IA-reactive HIV-infected persons with WB-negative results had been previously misclassified as uninfected, and HIV diagnosis was delayed for those with WB-indeterminate specimens. These findings underscore the limitations of the WB to confirm HIV infection after reactive results from contemporary 3rd or 4th generation IAs that can detect HIV antibodies several weeks sooner than the WB.

The health care community continues to battle the HIV epidemic. The keys to preventing the spread of this infection are to screen those at risk and get them into treatment. All patients infected with HIV should receive antiretroviral therapy (AR T) to achieve viral suppression. Getting patients to adhere with therapy and stay in care should be major goals for managed care plans.

The recent approval by the United States Food and Drug Administration of a rapid HIV self-test marks a significant milestone in the evolution of HIV testing approaches. With nearly one in five people living with HIV in the United States still undiagnosed and an even higher proportion unaware of their infection globally, this decision reflects a new willingness to offer diverse options to get tested for HIV. Rapid self-testing offers several distinct opportunities to improve testing among those with undiagnosed HIV: to encourage testing among those who might not otherwise be tested, to increase the frequency of testing among persons at highest risk for new infection, and to facilitate mutual HIV testing with sex partners. To date, the path to regulatory approval has been long but instructive. The studies and clinical trials required for regulatory approval in the United States provide insight into the performance and potential implications of HIV self-tests as they become available for sale directly to consumers. Although some persistent reservations about self-testing for HIV remain, including the 'window period' of the current test kit, its cost, and its effectiveness for facilitating entry to medical care, others have been dispelled. Self-testing in resource-constrained settings is also promising, including self-testing of health professionals. At present, although the impact has yet to be determined, availability of this new option might offer potential opportunities to improve HIV diagnosis and facilitate both treatment and prevention.

The value of HIV testing has grown in parallel with the development of increasingly effective HIV treatment. Evidence for the substantial reductions in transmission when persons receive antiretroviral therapy creates a new impetus to increase testing and early diagnosis. Models of treatment as prevention-dubbed "test and treat"-give reason for optimism that control and elimination of HIV may now be within reach. This will be possible only with widespread testing, prompt and accurate diagnosis, and universal access to immediate antiviral therapy. Many successful approaches for scaling up testing were pioneered in resource-limited countries before they were adopted by countries in the developed world. The future of HIV testing is changing. Lessons learned from other case-finding initiatives can help chart the course for comparable HIV testing endeavors.

2012 HIV Diagnostic Conference Atlanta, GA, USA, 12-14 December 2012. This report highlights the presentations and discussions from the 2012 National HIV Diagnostic Conference held in Atlanta (GA, USA), on 12-14 December 2012. Reflecting changes in the evolving field of HIV diagnostics, the conference provided a forum for evaluating developments in molecular diagnostics and their role in HIV diagnosis. In 2010, the HIV Diagnostics Conference concluded with the proposal of a new diagnostic algorithm which included nucleic acid testing to resolve discordant screening and supplemental antibody test results. The 2012 meeting, picking up where the 2010 meeting left off, focused on scientific presentations that assessed this new algorithm and the role played by RNA testing and new developments in molecular diagnostics, including detection of total and integrated HIV-1 DNA, detection and quantification of HIV-2 RNA, and rapid formats for detection of HIV-1 RNA.

In the United States, approximately 1.1 million adults and adolescents are living with human immunodeficiency virus (HIV) infection and, each year, another 50,000 become infected. At the end of 2008, approximately 20% of the persons living with HIV had an undiagnosed infection. Of those living with HIV at the end of 2008, nearly two thirds were racial/ethnic minorities and half were men who have sex with men (MSM). In 2007, HIV ranked fifth as a leading cause of death among persons aged 35-44 years in the United States but third among blacks or African Americans in this age group. In 40 states with longstanding confidential name-based HIV surveillance systems, 33% of the estimated 41,768 adults and adolescents diagnosed with HIV infection in 2008 developed acquired immunodeficiency syndrome (AIDS) within 1 year and, of these, 44% received their initial diagnosis in an acute care setting, suggesting that they received HIV testing late in the course of the infection. HIV-infected persons who are unaware of their infection or who receive a late diagnosis cannot benefit fully from timely initiation of therapy and are more likely to experience HIV-related morbidity and premature mortality. In addition, persons unaware of their infection are more likely to transmit HIV to others because of a higher prevalence of high-risk sexual behaviors and higher levels of viral RNA that continue to replicate without appropriate antiretroviral treatment.

OBJECTIVE: We evaluated the performance of the GS fourth-generation antigen/antibody assay and compared CDC's proposed alternative algorithm (repeatedly reactive [RR] fourth-generation immunoassay [IA] followed by an HIV-1/HIV-2 differentiation IA and, if needed, nucleic acid testing [NAT]) with the current algorithm (RR third-generation IA followed by HIV-1 Western blot [WB]). DESIGN: A convenience sample of the following four specimen sets was acquired: 10 014 from insurance applicants, 493 known WB-positive, 20 known WB-indeterminate specimens, and 230 specimens from 26 HIV-1 seroconverters. METHODS: Specimens were tested with the GS third- and fourth-generation IAs, the Multispot HIV-1/HIV-2 differentiation IA, NAT, and WB. We applied the two algorithms using these results. RESULTS: Among insurance specimens, 13 (0.13%) specimens were IA RR: 2 were HIV-positive (RR by third- and fourth-generation IAs, and WB and Multispot positive); 2 third-generation RR and 9 fourth-generation RR specimens were false-positive. Third- and fourth-generation specificities were 99.98% (95%CI: 99.93%-100%) and 99.91% (95%CI: 99.84%-99.96%) respectively.All HIV-1 WB-positive specimens were RR by third- and fourth-generation IAs. By Multispot, 491 (99.6%) were HIV-1 positive and 2 (0.4%) were HIV-2 positive. Only eight (40%) WB-indeterminate specimens were fourth-generation RR: 6 were Multispot and NAT negative and 2 were Multispot HIV-1 positive but NAT negative.The alternative algorithm correctly classified as positive 102 seroconverter specimens with the third-generation IA and 130 with the fourth-generation IA compared with 56 using the WB with either IA. CONCLUSIONS: The alternative testing algorithm improved early infection sensitivity and identified HIV-2 infections. Two potential false-positive algorithm results occurred with WB-indeterminate specimens.

Thirty years into the human immunodeficiency virus (HIV) epidemic in the United States, an estimated 50,000 persons become infected each year: highest rates are in black and Hispanic populations and in men who have sex with men. Testing for HIV has become more widespread over time, with the highest rates of HIV testing in populations most affected by HIV. However, approximately 55% of adults in the United States have never received an HIV test. Because of the individual and community benefits of treatment for HIV, in 2006 the Centers for Disease Control and Prevention recommended routine screening for HIV infection in clinical settings. The adoption of this recommendation has been gradual owing to a variety of issues: lack of awareness and misconceptions related to HIV screening by physicians and patients, barriers at the facility and legislative levels, costs associated with testing, and conflicting recommendations concerning the value of routine screening. Reducing or eliminating these barriers is needed to increase the implementation of routine screening in clinical settings so that more people with unrecognized infection can be identified, linked to care, and provided treatment to improve their health and prevent new cases of HIV infection in the United States.

OBJECTIVE: A 2004 national survey of hospitals showed that 23.4% of hospitals screened for HIV in at least one department, most frequently in labor and delivery departments. However, less than 2% of these hospitals screened patients in inpatient units, urgent care clinics, or emergency departments. In 2006, the Centers for Disease Control and Prevention (CDC) recommended HIV screening for all individuals 13-64 years of age in health-care settings. We determined the frequency of hospital adoption of these CDC recommendations. METHODS: We surveyed hospital infection-control personnel at a randomly selected sample of U.S. general medical and surgical hospitals in 2009-2010. RESULTS: Of the 1,476 hospitals selected for the survey, 754 (51.1%) responded to the survey; of those responding, 703 (93.2%) offered HIV tests for patients at the hospital and 206 (27.3%) screened for HIV in at least one department. Screening was most common in larger hospitals (45.7%), hospitals in large metropolitan areas (50.5%), and teaching hospitals (44.4%); it was least common in public hospitals (19.1%). By department, screening was most common in labor and delivery departments (34.6%) and substance abuse clinics (20.7%); it was least common in emergency departments (11.9%), inpatient units (9.6%), and psychiatry/mental health departments (9.4%). More than half of hospitals were not considering implementing CDC's recommendations within the next 12 months. CONCLUSIONS: Since 2004, HIV screening in hospitals increased overall and by department. However, the majority of U.S. hospitals have not adopted the CDC recommendations.

We conducted a study comparing the OraQuickADVANCE Rapid HIV-1/2 Antibody Test, Uni-Gold Recombigen HIV Test, Determine HIV 1/2 Ag/Ab Combo, EIA, and pooled nucleic acid amplification testing (NAAT). Men who have sex with men rated tests based on specimen collection method and trust in each test. Among 490 subjects, OraQuick performed on oral fluids ranked highest for specimen collection method but lowest on trust; NAAT scored highest on trust. Among a subset of these subjects, 46% would opt for NAAT if choosing one test. Strategies are needed to increase HIV testing that is accurate and consistent with client preferences.

Acute human immunodeficiency virus (HIV) infection poses a dilemma for diagnosis, clinical management, and public health. It has been variously defined as the transient symptomatic illness associated with high-titer viral replication [1], the period from initial infection to complete seroconversion [2], and the phase between the appearance of detectable HIV RNA and detectable antibodies to HIV [3]. In the context of therapeutic trials, primary HIV infection includes the acute infection interval and the first 6 months after seroconversion, during which viral set point is established [4, 5]. “Detecting acute infection” has also been used synonymously with “closing the window,” the period during which tests for HIV are negative in persons who are infected. | In this issue of the journal, Rosenberg et al [6] evaluated how well the Determine HIV-1/2 Ag/Ab Combo rapid test (Combo RT) compared with an algorithm of parallel antibody tests followed by RNA polymerase chain reaction. The Combo RT, designed for use at the point of care with finger-stick whole blood to detect HIV antibody and HIV antigen (and distinguish the two) in 20 minutes, did not fare very well in this comparison. The Combo RT is a lateral flow test (ie, an immunoassay that incorporates all necessary reagents into a single test strip). The test result is read visually, without instrumentation, after the specimen flows across the strip. Lateral flow tests have revolutionized HIV testing because they are easy to perform, require minimal training, have long-term stability, require no dedicated instrumentation, and can use whole blood specimens. In the United States, lateral flow HIV tests are used extensively in nonclinical settings. However, high hopes for point-of-care rapid tests able to identify acute infection, predicated on detecting p24 antigen, may be unrealistic. Recently developed fourth-generation HIV antigen-antibody (Ag/Ab) combination assays, designed for use in the laboratory, detect both p24 antigen and antibodies against HIV but do not distinguish between the two. They exhibit an analytic sensitivity for p24 antigen of 11–18 pg/mL [7], equivalent to approximately 30 000–50 000 copies/mL of HIV RNA [8]. In contrast, lateral flow assays using colloidal gold have a lower limit of detection in the range of 1 ng/mL [9], ∼100-fold higher than the p24 antigen concentration usually present in plasma [8]. With the ultrasensitive procedure that includes heat dissociation of p24 antigen–antibody immune complexes, signal amplification, and instrumentation, the limit of detection for p24 (without additional pretreatment of the specimen to disrupt viral particles) can be ≥250 000 RNA copies/mL [10]. The findings of Rosenberg et al substantiate this: ultrasensitive methods were used to test 7 of the 8 acute specimens and failed to detect p24 antigen in 2 that had RNA concentrations of 45 000 and ≥750 000 copies/mL.

BACKGROUND: An immunoassay (IA) followed by Western blot (WB) or immunofluorescence assay has been the primary algorithm used to provide laboratory confirmation of the diagnosis of HIV infection in the US for more than 20 years. Recently, an alternative diagnostic algorithm was proposed to more accurately identify early HIV-1 infection and differentiate between HIV-1 and HIV-2 infection. OBJECTIVES: Evaluate a sequential alternative algorithm in which reactive IAs are followed by a rapid HIV test and, if negative, a nucleic acid amplification test (NAAT). STUDY DESIGN: Specimens from high-risk persons were tested with 4 HIV IAs, 6 rapid HIV tests and NAAT (APTIMA((R))), which are approved by the United States Food and Drug Administration. IAs were repeated in duplicate if specimen volumes were sufficient. The performance of the alternative algorithm was compared to HIV WB and NAAT. RESULTS: The original study classified 377 specimens as HIV-positive and 3070 as HIV-negative. All 4 IAs correctly identified >99.5% of HIV-positive specimens and, on initial screening, >95.8% of HIV-negative specimens. When repeated, specificity of IAs improved to >99%. Between 6.7% and 12.4% of IA-repeatedly reactive specimens required APTIMA for resolution. The alternative algorithm led to the correct classification of all IA-reactive specimens. CONCLUSIONS: Regardless of screening IA and rapid test used, the alternative algorithm correctly classified the infection status of all persons with reactive screening IA results. Few specimens required NAAT for resolution, and the proportion requiring NAAT was lower when repeat IA test results were considered.

BACKGROUND: The HIV-1 Western blot (WB) and immunofluorescence assay used to confirm HIV infections are less sensitive during seroconversion than immunoassays (IAs) used for screening. An alternative diagnostic algorithm has been proposed to detect early HIV-1 infection and differentiate HIV-1 from HIV-2. OBJECTIVES: We evaluated the performance of an algorithm with a third generation IA that when reactive was followed by a rapid test (Multispot) that differentiates HIV-1 from HIV-2. Multispot-reactive specimens were considered HIV-infected. Multispot-negative specimens were tested with a nucleic acid amplification test (NAAT) for resolution. STUDY DESIGN: WB-positive specimens [serum (n=2202), plasma (n=1109) and peripheral blood mononuclear cells (PBMCs) (n=1065)] were obtained from HIV-infected persons not taking antiretrovirals. HIV-uninfected specimens [plasma (n=1517) and PBMCs (n=1508)] with negative IA and NAAT results were obtained from blood donors. Specimens were tested with third generation IAs (Abbott rDNA, ADVIA Centaur, GS HIV1-2 Plus O, Ortho VITROS) in singlet, Multispot, and NAAT (APTIMA (RNA) and AMPLICOR (DNA)). We calculated algorithm sensitivity and specificity and the proportion of IA-reactive specimens requiring NAAT. RESULTS: Algorithm sensitivity was 99.95% with APTIMA and 100% with AMPLICOR. One WB-positive specimen reactive by all IAs and AMPLICOR was negative by Multispot and APTIMA. Algorithm specificity was 100% using APTIMA or AMPLICOR as NAAT. From 0.10% (Abbott) to 2.43% (VITROS) of IA-reactive specimens required NAAT. CONCLUSIONS: The proposed algorithm performs with high sensitivity and specificity in specimens from persons with established HIV infection and uninfected blood donors and appears to be a good alternative to the current algorithm.

With the introduction of third generation antibody assays that detect both immunoglobulin (Ig) G and IgM class antibodies, and fourth generation antigen/antibody (Ag/Ab) combination assays, the ability of screening tests to detect early HIV infection has improved substantially over the past decade.1, 2, 3 Selecting the optimal tests to confirm the presence of HIV infection, however, poses a challenge for the laboratory. The traditional confirmatory tests, Western blot, line immunoassay, and indirect immunofluorscence assay, are highly specific and play a central role in diagnostic algorithms,4, 5, 6, 7 but they detect only IgG class antibodies.8 Thus, up to 3 weeks might elapse after a reactive third or fourth generation assay before the confirmatory tests produce a positive result. Molecular RNA assays, highly sensitive during early infection, yield negative results in 3–5% of specimens that are positive by Western blot.2, 9 Differentiating HIV-1 from HIV-2 poses another challenge. Almost all screening assays now incorporate antigens to detect both HIV-1 and HIV-2, but because of cross-reactivity, the HIV-1 Western blot is often positive in patients with HIV-2, and no HIV-2 confirmatory test is currently approved by the U.S. Food and Drug Administration (FDA).10, 11 “Cryptic” HIV-2 infection is thus often investigated only after patients with an HIV-1 diagnosis manifest clinical deterioration despite a repeatedly undetectable HIV-1 viral load.10

BACKGROUND: HIV-1 Western blot (WB) may be positive in specimens from persons with HIV-2 infection due to cross-reactive antibodies. HIV-1 and HIV-2 infections may be identified using assays designed to differentiate HIV-1 and HIV-2 antibody reactivity. OBJECTIVES: To evaluate the ability of the current CDC WB criteria, alternative more stringent HIV-1 WB criteria (2 env plus one gag or pol band) and the Multispot HIV-1/HIV-2 Rapid Test to accurately differentiate HIV-1 and HIV-2 infections. STUDY DESIGN: Two panels were used to determine the ability of each method to properly classify HIV-1 and HIV-2 infections: an HIV-2 panel (n=114) determined to be HIV-2 antibody-positive by both Multispot and by a validated HIV-2 WB, and 2135 HIV-1/HIV-2 immunoassay repeatedly reactive (IA-RR) specimens from the New York State Department of Health Laboratory (NYS). RESULTS: By CDC WB criteria, 53 (46.5%) HIV-2 panel specimens were HIV-1 WB positive, 60 (52.6%) were indeterminate, and 1 (0.9%) was negative; the alternative WB criteria re-classified 75.5% of the positives as indeterminate. Among 2135 NYS IA-RR specimens, the alternative WB criteria increased the proportion of indeterminates by 0.8%. Only 6 (0.3%) of the NYS specimens were determined to be HIV-2 infections; all 6 were classified either as HIV-1 positive or indeterminate by both WB criteria, but were classified as HIV-2 (n=4) or HIV-1/2 undifferentiated (n=2) by Multispot. CONCLUSIONS: The alternative WB criteria classified most of the HIV-2 specimens that were HIV-1 positive by CDC criteria as indeterminate, but also slightly increased the proportion of HIV-1 specimens classified as indeterminate. The WB indeterminate specimens would require further testing or follow-up to resolve the infection status, whereas Multispot directly distinguished HIV-1 from HIV-2.

BACKGROUND: The Centers for Disease Control and Prevention (CDC) estimates that 3.2 million Americans are living with chronic hepatitis C virus (HCV) infection and 50%-70% are unaware of their status. Although therapies are available that can suppress or eliminate infection, identifying persons infected with HCV is challenging. Rapid tests could help identify many of these persons more expeditiously. METHODS: Three manufacturers, Chembio, OraSure, and MedMira, submitted HCV antibody (anti-HCV) rapid screening assays to the CDC for evaluation and comparison with established anti-HCV screening assays. The panel consisted of 1100 specimens drawn during 1997-1999 from persons reporting injection drug use. Sensitivity and specificity were assessed using 2 reference approaches, one based on the reactivity of samples in an anti-HCV screening assay and the other based on CDC HCV testing algorithm. RESULTS: The sensitivities of the Chembio, MedMira, and OraSure assays across the 2 approaches were 96.2%-98.0%, 86.8%-88.3%, and 97.8%-99.3%, respectively. The 3 assays had specificity of 99.5% or higher with no differences between assays. False rapid assay results were associated with human immunodeficiency virus positivity for both approaches for Chembio and MedMira. CONCLUSIONS: Rapid anti-HCV tests can provide sensitive and specific anti-HCV results for high-risk patients.

Although previous studies have shown that HIV screening in emergency departments (EDs) is feasible, the costs and outcomes of alternative methods of implementing ED screening have not been examined. We compared the costs and outcomes of a model that used the hospital's ED staff to conduct screening, a supplemental staff model that used non-ED staff hired to conduct screening and a hypothetical hybrid model that combined aspects of both approaches. We developed a decision analytic model to estimate the cost per HIV-infected patient identified using alternative ED testing models. The cost per new HIV infection identified was $3,319, $2,084 and $1,850 under the supplemental, existing staff and hybrid models, respectively. Assuming an annual ED census of 50,000 patients, the existing staff model identified 29 more HIV infections than the supplemental model and the hybrid model identified 76 more infections than the existing staff model. Our findings suggest that a hybrid model should be favored over either a supplemental staff or existing staff model in terms of cost per outcome achieved.

BACKGROUND: Performance of the BED assay in estimating HIV-1 incidence has previously been evaluated by using longitudinal specimens from persons with incident HIV infections, but questions remain about its accuracy. We sought to assess its performance in three longitudinal cohorts from Thailand where HIV-1 CRF01_AE and subtype B' dominate the epidemic. DESIGN: BED testing was conducted in two longitudinal cohorts with only incident infections (a military conscript cohort and an injection drug user cohort) and in one longitudinal cohort (an HIV-1 vaccine efficacy trial cohort) that also included long-term infections. METHODS: Incidence estimates were generated conventionally (based on the number of annual serocoversions) and by using BED test results in the three cohorts. Adjusted incidence was calculated where appropriate. RESULTS: For each longitudinal cohort the BED incidence estimates and the conventional incidence estimates were similar when only newly infected persons were tested, whether infected with CRF01_AE or subtype B'. When the analysis included persons with long-term infections (to mimic a true cross-sectional cohort), BED incidence estimates were higher, although not significantly, than the conventional incidence estimates. After adjustment, the BED incidence estimates were closer to the conventional incidence estimates. When the conventional incidence varied over time, as in the early phase of the injection drug user cohort, the difference between the two estimates increased, but not significantly. CONCLUSIONS: Evaluation of the performance of incidence assays requires the inclusion of a substantial number of cohort-derived specimens from individuals with long-term HIV infection and, ideally, the use of cohorts in which incidence remained stable. Appropriate adjustments of the BED incidence estimates generate estimates similar to those generated conventionally.

BACKGROUND: Since 2002, the US Food and Drug Administration has approved 6 rapid human immunodeficiency virus (HIV) tests for use in the United States. To date, there has been no direct comparison of the performance of all 6 tests. METHODS: Persons known to be HIV-infected and persons who sought HIV testing at 2 clinical sites in Los Angeles, California, were recruited for evaluation of 6 rapid HIV tests with whole blood, oral fluid, serum, and plasma specimens. Sensitivity and specificity of the rapid tests were compared with viral lysate and immunoglobulin (Ig) M-sensitive peptide HIV enzyme immunoassays (EIAs). RESULTS: A total of 6282 specimens were tested. Sensitivity was >95% and specificity was >99% for all rapid tests. Compared with the IgM-sensitive EIA, rapid tests gave false-negative results with an additional 2-5 specimens. All rapid tests had statistically equivalent performance characteristics, based on overlapping confidence intervals for sensitivity and specificity, compared with either conventional EIA. CONCLUSIONS: All 6 rapid tests have high sensitivity and specificity, compared with that of conventional EIAs. Because performance was similar for all tests and specimen types, other characteristics, such as convenience, time to result, shelf life, and cost will likely be determining factors for selection of a rapid HIV screening test for a specific application.