Diagnosis and management of acute HIV infection

In utero and intra-partum HIV-1 transmission and acute HIV-1 infection during pregnancy: using the BED capture enzyme-immunoassay as a surrogate marker for acute infection

OBJECTIVE

The BED assay was developed to estimate the proportion of recent HIV infections in a population. We used the BED assay as a proxy for acute infection to quantify the associated risk of mother-to-child-transmission (MTCT) during pregnancy and delivery. Design A total of 3773 HIV-1 sero-positive women were tested within 96 h of delivery using the BED assay, and CD4 cell count measurements were taken. Mothers were classified according to their likelihood of having recently seroconverted.

METHODS

The risk of MTCT in utero and intra-partum was assessed comparing different groups defined by BED and CD4 cell count, adjusting for background factors using multinomial logistic models.

RESULTS

Compared with women with BED ≥ 0.8/CD4 ≥ 350 (typical of HIV-1 chronic patients) there was insufficient evidence to conclude that women presenting with BED < 0.8/CD4 ≥ 350 (typical of recent infections) were more likely to transmit in utero [adjusted odds ratio (aOR) = 1.37, 96% confidence interval (CI) 0.90-2.08, P = 0.14], whereas women with BED < 0.8/CD4 200-349 (possibly recently infected patients) had a 2.57 (95% CI 1.39-4.77, P-value < 0.01) odds of transmitting in utero. Women who had BED < 0.8/CD4 < 200 were most likely to transmit in utero (aOR 3.73, 95% CI 1.27-10.96, P = 0.02). BED and CD4 cell count were not predictive of intra-partum infections.

CONCLUSIONS

These data provide evidence that in utero transmission of HIV might be higher among women who seroconvert during pregnancy.

Lower HIV prevalence among Asian/Pacific Islander men who have sex with men: a critical review for possible reasons

We conducted a critical literature review for possible reasons that may explain the lower HIV prevalence observed among API MSM compared to MSM of other races/ethnicities. Trends emerging from the literature suggest that traditional individual-level factors-unprotected anal intercourse, substance use, STD prevalence, rates and frequency of HIV testing, and utilization of HIV prevention services-do not appear to be related to the lower HIV prevalence among API MSM. Some evidence suggests that socio-cultural and structural factors might be the more critical forces in determining racial/ethnic disparities of HIV among MSM. For API MSM, these factors include structures of sexual networks, access to and reception of medical care and treatment among HIV-positive MSM, and influences of different levels and types of acculturation. Moreover, emerging risk reduction strategies, such as seroadaptive behaviors, could play a role. Future research should address these factors in intervention design. In addition, better theories of resilience and measurement of strengths and protective factors are needed to enhance the efficacy of HIV interventions.

Cost-effectiveness of pooled nucleic acid amplification testing for acute HIV infection after third-generation HIV antibody screening and rapid testing in the United States: a comparison of three public health settings

BACKGROUND

Detection of acute HIV infection (AHI) with pooled nucleic acid amplification testing (NAAT) following HIV testing is feasible. However, cost-effectiveness analyses to guide policy around AHI screening are lacking; particularly after more sensitive third-generation antibody screening and rapid testing.

METHODS AND FINDINGS

We conducted a cost-effectiveness analysis of pooled NAAT screening that assessed the prevention benefits of identification and notification of persons with AHI and cases averted compared with repeat antibody testing at different intervals. Effectiveness data were derived from a Centers for Disease Control and Prevention AHI study conducted in three settings: municipal sexually transmitted disease (STD) clinics, a community clinic serving a population of men who have sex with men, and HIV counseling and testing sites. Our analysis included a micro-costing study of NAAT and a mathematical model of HIV transmission. Cost-effectiveness ratios are reported as costs per quality-adjusted life year (QALY) gained in US dollars from the societal perspective. Sensitivity analyses were conducted on key variables, including AHI positivity rates, antibody testing frequency, symptomatic detection of AHI, and costs. Pooled NAAT for AHI screening following annual antibody testing had cost-effectiveness ratios exceeding US$200,000 per QALY gained for the municipal STD clinics and HIV counseling and testing sites and was cost saving for the community clinic. Cost-effectiveness ratios increased substantially if the antibody testing interval decreased to every 6 months and decreased to cost-saving if the testing interval increased to every 5 years. NAAT was cost saving in the community clinic in all situations. Results were particularly sensitive to AHI screening yield.

CONCLUSIONS

Pooled NAAT screening for AHI following negative third-generation antibody or rapid tests is not cost-effective at recommended antibody testing intervals for high-risk persons except in very high-incidence settings.

Role of acute and early HIV infection in the sexual transmission of HIV

PURPOSE OF REVIEW

Acute HIV infection (AHI), the earliest period after HIV acquisition, is only a few weeks in duration. In this brief period, the concentration of HIV in blood and genital secretions is extremely high, increasing the probability of HIV transmission. Although a substantial role of AHI in the sexual transmission of HIV is biologically plausible, the significance of AHI in the epidemiological spread of HIV remains uncertain.

RECENT FINDINGS

AHI is diagnosed by detecting viral RNA or antigen in the blood of persons who are HIV seronegative. Depending on the setting, persons with AHI represent between 1 and 10% of persons with newly diagnosed HIV infection. The high concentration of virus during AHI leads to increased infectiousness, possibly as much as 26 times greater than during chronic infection. In mathematical models, the estimated proportion of transmission attributed to AHI has varied considerably, depending on model structure, model parameters, and the population. Key determinants include the stage of the HIV epidemic and the sexual risk profile of the population.

SUMMARY

Despite its brief duration, AHI plays a disproportionate role in the sexual transmission of HIV infection. Detection of persons with AHI may provide an important opportunity for transmission prevention.

Acute HIV-1 infection is highly prevalent in Ugandan adults with suspected malaria

OBJECTIVES

Acute febrile illnesses consistent with malaria are the most common presentation at health clinics in sub-Saharan Africa, accounting for 30-50% of outpatient visits. The symptoms of acute HIV infection can mimic acute malaria. We investigated whether acute HIV infections could be identified among adults with suspected malaria at rural health centers in Uganda.

DESIGN

A cross-sectional study of 1000 consecutive patients referred for malaria blood smears at each of seven government health centers, of which 2893 (41%) were 13 years or older and tested for HIV.

METHODS

HIV enzyme immunoassay antibody testing was performed on dried blood spots and confirmed by western blot. Enzyme immunoassay-nonreactive and enzyme immunoassay-reactive, western blot-unconfirmed samples were pooled (10/pool) and tested for HIV RNA by nucleic acid amplification testing. We defined acute HIV infection as HIV-1 RNA positive with a negative or indeterminate HIV-1 western blot pattern and early HIV infection as HIV-1 RNA positive with a positive western blot pattern, but with a BED-corrected optical density of below 0.8.

RESULTS

Of 2893 patients evaluated, 324 (11%) had test results indicating HIV infection. Overall, 30 patients (1.0%) had acute HIV infection, 56 (1.8%) had early HIV infection, and 238 (8%) had established HIV infection. Acute HIV infections were more prevalent at sites with higher HIV prevalence and lower malaria endemicity.

CONCLUSION

At multiple sites in Uganda, 1-3% of adults with suspected malaria had acute or early HIV infection. These findings highlight a major opportunity for expanding recognition of acute and early HIV infection in Africa.

The failure of routine rapid HIV testing: a case study of improving low sensitivity in the field

BACKGROUND

The rapid HIV antibody test is the diagnostic tool of choice in low and middle-income countries. Previous evidence suggests that rapid HIV diagnostic tests may underperform in the field, failing to detect a substantial number of infections. A research study inadvertently discovered that a clinic rapid HIV testing process was failing to detect cases of established (high antibody titer) infection, exhibiting an estimated 68.7% sensitivity (95% CI [41.3%-89.0%]) over the course of the first three weeks of observation. The setting is a public service clinic that provides STI diagnosis and treatment in an impoverished, peri-urban community outside of Cape Town, South Africa.

METHODS

The researchers and local health administrators collaborated to investigate the cause of the poor test performance and make necessary corrections. The clinic changed the brand of rapid test being used and later introduced quality improvement measures. Observations were made of the clinic staff as they administered rapid HIV tests to real patients. Estimated testing sensitivity was calculated as the number of rapid HIV test positive individuals detected by the clinic divided by this number plus the number of PCR positive, highly reactive 3rd generation ELISA patients identified among those who were rapid test negative at the clinic.

RESULTS

In the period of five months after the clinic made the switch of rapid HIV tests, estimated sensitivity improved to 93.5% (95% CI [86.5%-97.6%]), during which time observations of counselors administering tests at the clinic found poor adherence to the recommended testing protocol. Quality improvement measures were implemented and estimated sensitivity rose to 95.1% (95% CI [83.5%-99.4%]) during the final two months of full observation.

CONCLUSIONS

Poor testing procedure in the field can lead to exceedingly low levels of rapid HIV test sensitivity, making it imperative that stringent quality control measures are implemented where they do not already exist. Certain brands of rapid-testing kits may perform better than others when faced with sub-optimal use.

Compartmentalization and clonal amplification of HIV-1 variants in the cerebrospinal fluid during primary infection

Human immunodeficiency virus type 1 (HIV-1)-associated dementia (HAD) is a severe neurological disease that affects a subset of HIV-1-infected individuals. Increased compartmentalization has been reported between blood and cerebrospinal fluid (CSF) HIV-1 populations in subjects with HAD, but it is still not known when compartmentalization arises during the course of infection. To assess HIV-1 genetic compartmentalization early during infection, we compared HIV-1 populations in the peripheral blood and CSF in 11 primary infection subjects, with analysis of longitudinal samples over the first 18 months for a subset of subjects. We used heteroduplex tracking assays targeting the variable regions of env and single-genome amplification and sequence analysis of the full-length env gene to identify CSF-compartmentalized variants and to examine viral genotypes within the compartmentalized populations. For most subjects, HIV-1 populations were equilibrated between the blood and CSF compartments. However, compartmentalized HIV-1 populations were detected in the CSF of three primary infection subjects, and longitudinal analysis of one subject revealed that compartmentalization during primary HIV-1 infection was resolved. Clonal amplification of specific HIV-1 variants was identified in the CSF population of one primary infection subject. Our data show that compartmentalization can occur in the central nervous system (CNS) of subjects in primary HIV-1 infection in part through persistence of the putative transmitted parental variant or via viral genetic adaptation to the CNS environment. The presence of distinct HIV-1 populations in the CSF indicates that independent HIV-1 replication can occur in the CNS, even early after HIV-1 transmission.

Strategies used in the detection of acute/early HIV infections. The NIMH Multisite Acute HIV Infection Study: I

Acute/early HIV infection plays a critical role in onward HIV transmission. Detection of HIV infections during this period provides an important early opportunity to offer interventions which may prevent further transmission. In six US cities, persons with acute/early HIV infection were identified using either HIV RNA testing of pooled sera from persons screened HIV antibody negative or through clinical referral of persons with acute or early infections. Fifty-one cases were identified and 34 (68%) were enrolled into the study; 28 (82%) were acute infections and 6 (18%) were early infections. Of those enrolled, 13 (38%) were identified through HIV pooled testing of 7,633 HIV antibody negative sera and 21 (62%) through referral. Both strategies identified cases that would have been missed under current HIV testing and counseling protocols. Efforts to identify newly infected persons should target specific populations and geographic areas based on knowledge of the local epidemiology of incident infections.

Detection of HIV-1 in alternative specimen types using the APTIMA HIV-1 RNA Qualitative Assay

Peripheral blood mononuclear cells (PBMCs), saliva, seminal plasma, and dried blood spots were evaluated as specimen types for the APTIMA HIV-1 RNA Qualitative Assay (APTIMA HIV-1 Assay), which employs a target capture step to recover HIV-1-specific sequences from complex specimen types. Analytical sensitivity studies were carried out using samples that were either diluted or eluted with a buffered detergent and spiked with different concentrations of HIV-1 ranging from 1 to 10,000 copies/mL. PBMC samples spiked with HIV-1 had comparable analytical sensitivity to HIV-1 spiked plasma with a 95% limit of detection of 13.1 and 17.2 copies/mL, respectively. Analytical sensitivity in seminal plasma specimens diluted 1:5 and saliva diluted 1:2 was comparable to HIV-1 spiked dilution buffer alone. Whole blood and dried blood spot specimens spiked with HIV-1 had equivalent reactivity at 250 copies/spot (5000 copies/mL). However, the 95% limit of detection values were significantly different (293.7 copies/mL for whole blood and 2384 copies/mL for dried blood spot specimens). No significant effect on analytical sensitivity was observed when one HIV-1 positive dried blood spot punch was pooled with up to 9 HIV-1 negative dried blood spot punches. Together, these studies demonstrate that the APTIMA HIV-1 RNA Qualitative Assay can be used to process a diverse array of specimen types with minimal impact on analytical sensitivity for most specimen types.

Prevalence and correlates of unknown HIV infection among patients seeking care in a public hospital emergency department

OBJECTIVES

Screening for human immunodeficiency virus (HIV) infection in the emergency department (ED) has been proposed as an effective approach to increase early HIV diagnosis. To evaluate the potential for the implementation of routine screening, we determined the prevalence of unknown HIV infection among patients being seen in an urban public hospital ED.

METHODS

We conducted a cross-sectional study among patients presenting to the San Francisco General Hospital's ED during March 2007. We reviewed patients' medical records to determine HIV infection status. In patients with unknown or negative HIV-infection status, we tested de-identified remnant blood specimens by HIV-antibody and nucleic-acid assays. We used a sensitive/less sensitive testing algorithm to determine the duration of HIV infection.

RESULTS

During the study period, 1,820 patients had blood collected for clinical evaluation. Of those patients, 146 (8.0%) were known to be HIV-infected. Among the remaining 1,674 patients with unknown HIV-infection status, HIV-infection prevalence was 0.9% (15 of 1,674, 95% confidence interval [CI] 0.55, 1.47). In addition, one case of acute HIV infection (HIV-antibody negative, HIV RNA detected) was identified. Patients with unknown HIV infection vs. those who were uninfected were more likely to be homeless (odds ratio [OR] = 3.89, 95% CI 1.32, 11.45, p<0.05) and 18 to 30 years of age (OR=3.15, 95% CI 1.03, 9.61, p<0.05).

CONCLUSIONS

In a sample of patients visiting a county ED, the relative prevalence of unknown HIV infection (10%) was modest and less than national estimates (25%). Acutely HIV-infected patients might account for a significant proportion of those with unknown HIV infection in an ED setting.

National estimation of rates of HIV serology testing in US emergency departments 1993-2005: baseline prior to the 2006 Centers for Disease Control and Prevention recommendations

OBJECTIVE

The 2006 Centers for Disease Control and Prevention recommendations place increased emphasis on emergency departments (EDs) as one of the most important medical care settings for implementing routine HIV testing. No longitudinal estimates exist regarding national rates of HIV testing in EDs. We analyzed a nationally representative ED database to assess HIV testing rates and characterize patients who received HIV testing, prior to the release of the 2006 guidelines.

DESIGN

A cross-sectional analysis of US ED visits (1993-2005) using the National Hospital Ambulatory Medical Care Survey was performed.

METHODS

Patients aged 13-64 years were included for analysis. Diagnoses were grouped with Healthcare Cost and Utilization Project Clinical Classifications Software. Analyses were performed using procedures for multiple-stage survey data.

RESULTS

HIV testing was performed in an estimated 2.8 million ED visits (95% confidence interval, 2.4-3.2) or a rate of 3.2 per 1000 ED visits (95% confidence interval, 2.8-3.7). Patients aged 20-39 years, African-American, and Hispanic had the highest testing rates. Among those tested, leading reasons for visit were abdominal pain (9%), puncture wound/needlestick (8%), rape victim (6%), and fever (5%). The leading medication class prescribed was antimicrobials (32%). The leading ED diagnosis was injury/poisoning (30%) followed by infectious diseases (18%). Of note, 6% of those tested were diagnosed with HIV infection during their ED visits.

CONCLUSION

Prior to the release of the 2006 Centers for Disease Control and Prevention guidelines for routine HIV testing in all healthcare settings, baseline national HIV testing rates in EDs were extremely low and appeared to be driven by clinical presentation.

Beyond the end of exceptionalism: integrating HIV testing into routine medical care and HIV prevention

In September 2006, the US CDC issued new guidelines for HIV testing. These guidelines were designed not only to simplify and expand HIV testing but also to integrate testing into routine medical care in the USA. The nationwide implementation of these guidelines is currently facing several political and legal barriers. In this article, we examine the origins of current patient-driven and risk-based HIV testing in the USA and highlight shortcomings of this strategy. We then demonstrate how the changing HIV epidemic in the USA requires routine HIV screening at all points of contact in the medical system in order to control the HIV epidemic and how novel testing strategies could increase the yield of testing in these settings.