Approaching "HIV elimination": Interventions for acute HIV infection

Diminishing Perceived Threat of AIDS and Increasing Sexual Risks of HIV Among Men Who Have Sex with Men, 1997-2015

Community-wide awareness that antiretroviral therapies (ART) provides protection against HIV has the potential to increase perceived safety and thereby increase condomless anal sex among men who have sex with men (MSM). Furthermore, reductions in condom use can increase exposure to sexually transmitted infections, which in turn can reduce the protective effects of ART on HIV transmission. The current study extends previous community-based behavioral surveillance research on beliefs regarding use of ART for HIV prevention and sexual practices among MSM. Anonymous cross-sectional community surveys were collected from 1831 men at the same gay pride event in Atlanta, GA four times over nearly two decades; 1997, 2005-2006 (the 2006 survey over-sampled African-Americans to diversify the study), and 2015. Results indicate clear and consistent trends of increasing beliefs that HIV treatments reduce HIV transmission risks, reflecting the dissemination of HIV prevention research findings. Changes in treatment beliefs coincide with increased rates of condomless anal intercourse. Increased beliefs that treatments prevent HIV and increased condomless anal sex were observed for both HIV positive men and men who had not tested HIV positive. Results illustrate the emergence of an era where ART is the focus of HIV prevention and community-held beliefs and behaviors regarding definitions of risk create a new and potentially problematic environment for HIV transmission.

Evaluation of SMARTube to Detect HIV Infection Before Seroconversion Using Standard Methods

The acute phase of HIV infection carries substantial risk of transmission; identification of acute-phase infections may offer opportunities to reduce that risk. SMARTube incubation of blood specimens is designed to stimulate in vivo-primed HIV-specific lymphocytes to produce HIV antibodies in vitro. The resulting supernatant (S-plasma) can be tested to identify acute infections with commercially available HIV assays. We assessed the performance of the SMARTube to identify acute HIV infections in studies at three developing country sites. We conducted HIV incidence studies in Ho Chi Minh City, Vietnam, and Bloemfontein and Rustenburg, South Africa. We estimated HIV incidence in cross-sectional samples and measured prospective incidence in uninfected women followed for up to 12 months. We incorporated SMARTube into the HIV testing algorithm at cross-sectional screening and monthly follow-up visits. We tested 1,384 persons in Vietnam, 1,145 women in Bloemfontein, and 538 persons in Rustenburg. Cross-sectional samples from 11 participants that tested positive with SMARTube after an initial unincubated negative test result (11 of 2,472; 0.4% of all specimens) were considered "potential acute" infections. Matching samples from 3 of the 11 (27.3%) were confirmed by polymerase chain reaction (PCR) testing. In follow-up of 355, 401, and 223 uninfected women in Vietnam, Bloemfontein, and Rustenburg, respectively, 11 seroconversions occurred in Bloemfontein and Rustenburg. In four of these incident infections (36.4%), SMARTube testing had resulted in earlier detection of HIV infection than the eventual seroconversion visits. In our field studies, pretreatment with SMARTube allowed the identification of acute HIV-1 infection in some new infections, but with a positive predictive value of 27%. Larger studies are needed to evaluate SMARTube as an alternative to technically challenging and costly enzyme immunoassay and PCR testing to detect acute HIV infection.

Patient experiences following acute HIV infection diagnosis and counseling in South Africa

Individuals in the acute stage of HIV infection (AHI) have an elevated potential to transmit HIV and play a critical role in the growth of the epidemic. Routine identification and counseling of individuals during AHI could decrease transmission behavior during this key period. However, diagnosis of AHI may present challenges distinct from those experienced through diagnosis of established HIV infection. A study was conducted in a public youth clinic outside of Cape Town, South Africa, to identify and counsel individuals with acute stage HIV infection. In-depth interviews were conducted with patients following diagnosis. After counseling, patients were accepting of the testing regimen used to diagnose AHI. They used the knowledge of having been recently infected to identify the source of their infection, but did not retain or place importance on information regarding the increased ability to transmit HIV during the acute stage. Future interventions directed at the reduction of HIV transmission following diagnosis with AHI will need to find ways of making this information more salient, possibly through more culturally meaningful educational approaches.

Point of Care Technologies for HIV

Effective prevention of HIV/AIDS requires early diagnosis, initiation of therapy, and regular plasma viral load monitoring of the infected individual. In addition, incidence estimation using accurate and sensitive assays is needed to facilitate HIV prevention efforts in the public health setting. Therefore, more affordable and accessible point-of-care (POC) technologies capable of providing early diagnosis, HIV viral load measurements, and CD4 counts in settings where HIV is most prevalent are needed to enable appropriate intervention strategies and ultimately stop transmission of the virus within these populations to achieve the future goal of an AIDS-free generation. This review discusses the available and emerging POC technologies for future application to these unmet public health needs.

Challenges and potential barriers to the uptake of antiretroviral-based prevention in Asia and the Pacific region

Evidence has emerged over the past few years on the effectiveness of antiretroviral-based prevention technologies to prevent (i) HIV transmission while decreasing morbidity and mortality in HIV-infected persons, and (ii) HIV acquisition in HIV-uninfected individuals through pre-exposure prophylaxis (PrEP). Only few of the planned studies on treatment as prevention (TasP) are conducted in Asia. TasP might be more feasible and effective in concentrated rather than in generalised epidemics, as resources for HIV testing and antiretroviral treatment could focus on confined and much smaller populations than in the generalised epidemics observed in sub-Saharan Africa. Several countries such as Cambodia, China, Thailand and Vietnam, are now paving the way to success. Similar challenges arise for both TasP and PrEP. However, the operational issues for PrEP are amplified by the need for frequent retesting and ensuring adherence. This paper describes challenges for the implementation of antiretroviral-based prevention and makes the case that TasP and PrEP implementation research in Asia is much needed to provide insights into the feasibility of these interventions in populations where firm evidence of ‘real world’ effectiveness is still lacking.

Participation in research involving novel sampling and study designs to identify acute HIV-1 infection among minority men who have sex with men

HIV-1 infection disproportionally affects African-American and Latino men who have sex with men (MSM). Their inclusion in biomedical and behavioral research is critical to understanding and addressing HIV vulnerability. Using focus groups, we sought to understand the perceptions related to participating in biomedical research of acute/recent HIV-1 infection (AHI) using complex sampling and data collection methods to reach this hidden group at highest risk of acquiring and transmitting HIV. Given the potential impact of AHI on HIV transmission in MSM, it is important to understand this intersection for HIV prevention, care, and treatment purposes. The aim of this study was to understand how recruitment and data collection methods affect AHI research participation willingness particularly among MSM of color. Findings suggest that major barriers to research participation with complex sampling to identify AHI and intensive risk behavior collection such as diary methods are lack of anonymity, partner disclosure, and study fatigue. The authors explore implications for future study designs and development based on these findings.

Cost effectiveness of screening strategies for early identification of HIV and HCV infection in injection drug users

OBJECTIVE

To estimate the cost, effectiveness, and cost effectiveness of HIV and HCV screening of injection drug users (IDUs) in opioid replacement therapy (ORT).

DESIGN

Dynamic compartmental model of HIV and HCV in a population of IDUs and non-IDUs for a representative U.S. urban center with 2.5 million adults (age 15-59).

METHODS

We considered strategies of screening individuals in ORT for HIV, HCV, or both infections by antibody or antibody and viral RNA testing. We evaluated one-time and repeat screening at intervals from annually to once every 3 months. We calculated the number of HIV and HCV infections, quality-adjusted life years (QALYs), costs, and incremental cost-effectiveness ratios (ICERs).

RESULTS

Adding HIV and HCV viral RNA testing to antibody testing averts 14.8-30.3 HIV and 3.7-7.7 HCV infections in a screened population of 26,100 IDUs entering ORT over 20 years, depending on screening frequency. Screening for HIV antibodies every 6 months costs $30,700/QALY gained. Screening for HIV antibodies and viral RNA every 6 months has an ICER of $65,900/QALY gained. Strategies including HCV testing have ICERs exceeding $100,000/QALY gained unless awareness of HCV-infection status results in a substantial reduction in needle-sharing behavior.

DISCUSSION

Although annual screening for antibodies to HIV and HCV is modestly cost effective compared to no screening, more frequent screening for HIV provides additional benefit at less cost. Screening individuals in ORT every 3-6 months for HIV infection using both antibody and viral RNA technologies and initiating ART for acute HIV infection appears cost effective.

Opportunities and challenges for cost-efficient implementation of new point-of-care diagnostics for HIV and tuberculosis

Stakeholders agree that supporting high-quality diagnostics is essential if we are to continue to make strides in the fight against human immunodeficiency virus (HIV) and tuberculosis. Despite the need to strengthen existing laboratory infrastructure, which includes expanding and developing new laboratories, there are clear diagnostic needs where conventional laboratory support is insufficient. Regarding HIV, rapid point-of-care (POC) testing for initial HIV diagnosis has been successful, but several needs remain. For tuberculosis, several new diagnostic tests have recently been endorsed by the World Health Organization, but a POC test remains elusive. Human immunodeficiency virus and tuberculosis are coendemic in many high prevalence locations, making parallel diagnosis of these conditions an important consideration. Despite its clear advantages, POC testing has important limitations, and laboratory-based testing will continue to be an important component of future diagnostic networks. Ideally, a strategic deployment plan should be used to define where and how POC technologies can be most efficiently and cost effectively integrated into diagnostic algorithms and existing test networks prior to widespread scale-up. In this fashion, the global community can best harness the tremendous capacity of novel diagnostics in fighting these 2 scourges.

Towards targeted screening for acute HIV infections in British Columbia

BACKGROUND

Our objective was to describe the characteristics of acute and established HIV infections diagnosed in the Canadian province of British Columbia. Province-wide HIV testing and surveillance data were analyzed to inform recommendations for targeted use of screening algorithms to detect acute HIV infections.

METHODS

Acute HIV infection was defined as a confirmed reactive HIV p24 antigen test (or HIV nucleic acid test), a non-reactive or reactive HIV EIA screening test and a non-reactive or indeterminate Western Blot. Characteristics of unique individuals were identified from the British Columbia HIV/AIDS Surveillance System. Primary drug resistance and HIV subtypes were identified by analyzing HIV pol sequences from residual sera from newly infected individuals.

RESULTS

From February 2006 to October 2008, 61 individuals met the acute HIV infection case definition, representing 6.2% of the 987 newly diagnosed HIV infections during the analysis period. Acute HIV infection cases were more likely to be men who have sex with men (crude OR 1.71; 95% CI 1.01-2.89], to have had a documented previous negative HIV test result (crude OR 2.89; 95% CI 1.52-5.51), and to have reported a reason for testing due to suspected seroconversion symptoms (crude OR 5.16; 95% CI 2.88-9.23). HIV subtypes and rates of transmitted drug resistance across all classes of drugs were similar in persons with both acute and established HIV infections.

CONCLUSIONS

Targeted screening to detect acute HIV infection is a logical public health response to the HIV epidemic. Our findings suggest that acute HIV infection screening strategies, in our setting, are helpful for early diagnosis in men who have sex with men, in persons with seroconversion symptoms and in previously negative repeat testers.

Genital shedding of HIV after scheduled treatment interruption

This study assessed genital shedding of HIV in patients on intermittent combination antiretroviral therapy (cART) and assessed predictors of having detectable genital HIV RNA in 156 Thai patients with CD4 > 350 cells/μL and HIV RNA ≤50 copies/mL who were randomized to continuous therapy (CT, n = 65) or CD4-guided cART (n = 91). There were 383 matched genital and plasma HIV RNA samples (CT: 158, CD4 guided: 225). In 14 samples collected within eight weeks of treatment interruption, detectable HIV RNA was present in 29% of genital samples and 71% of plasma samples. In 55 samples collected after eight weeks of treatment interruption, detectable HIV RNA was present in 60% of genital samples and 98% of plasma samples. In 110 samples collected up to 96 weeks after treatment re-initiation, detectable genital HIV RNA was found in 8% of samples and all of these were within the first 17 weeks. Independent predictors of detectable genital HIV RNA were increasing age and increasing concentrations of HIV RNA in plasma. These findings support the role of cART in maintaining undetectable HIV RNA in genital secretions.

Sexually transmitted infections and infectiousness beliefs among people living with HIV/AIDS: implications for HIV treatment as prevention

OBJECTIVES

Sexually transmitted infections (STIs) significantly impact the health of people living with HIV/AIDS, increasing HIV infectiousness and therefore transmissibility. The current study examined STIs in a community sample of 490 HIV-positive men and women.

METHODS

Assessments were performed using confidential computerized interviews in a community research setting.

RESULTS

Fourteen per cent of the people living with HIV/AIDS in this study had been diagnosed with a new STI in a 6-month period. Individuals with a new STI had significantly more sexual partners in that time period, including non-HIV-positive partners. Participants who had contracted an STI were significantly more likely to have detectable viral loads and were less likely to know their viral load than participants who did not contract an STI. Multivariate analysis showed that believing an undetectable viral load leads to lower infectiousness was associated with contracting a new STI.

CONCLUSIONS

Individuals who believed that having an undetectable viral load reduces HIV transmission risks were more likely to be infectious because of STI coinfection. Programmes that aim to use HIV treatment for HIV prevention must address infectiousness beliefs and aggressively control STIs among people living with HIV/AIDS.

Behavioral changes associated with testing HIV-positive among sexually transmitted infection clinic patients in Cape Town, South Africa

OBJECTIVES

We sought to examine behavioral risks and behavior changes associated with testing HIV-positive among sexually transmitted infection (STI) patients, in order to inform HIV- and STI-prevention interventions.

METHODS

We performed a cohort study of 29 STI patients who seroconverted from HIV-negative to HIV-positive during 1 year of observation and 77 STI patients who persistently tested HIV-negative. Computerized behavioral interviews were collected at baseline and at 1 year, and STI clinic charts were abstracted over the same 1-year period.

RESULTS

The STI patients who reported genital bleeding during sexual activity at baseline were significantly more likely to test HIV-positive. Reductions in number of sexual partners and rates of unprotected intercourse occurred for all STI clinic patients regardless of whether they tested HIV-positive.

CONCLUSIONS

Although risk reductions occurred, 5% of HIV-negative STI clinic patients subsequently tested HIV-positive over 1 year. Behavioral risk-reduction interventions are urgently needed for male and female STI clinic patients.

Sexual partner selection and HIV risk reduction among Black and White men who have sex with men

OBJECTIVES

We examined differences in sexual partner selection between Black and White men who have sex with men (MSM) to better understand how HIV status of participants' sexual partners and related psychosocial measures influence risk taking among these men.

METHODS

We collected cross-sectional surveys from self-reported HIV-negative Black MSM and White MSM attending a gay pride festival in Atlanta, Georgia.

RESULTS

HIV-negative White MSM were more likely than were HIV-negative Black MSM to report having unprotected anal intercourse with HIV-negative men, and HIV-negative Black MSM were more likely than were HIV-negative White MSM to report having unprotected anal intercourse with HIV status unknown partners. Furthermore, White MSM were more likely to endorse serosorting (limiting unprotected partners to those who have the same HIV status) beliefs and favorable HIV disclosure beliefs than were Black MSM.

CONCLUSIONS

White MSM appear to use sexual partner-related risk reduction strategies to reduce the likelihood of HIV infection more than do Black MSM. Partner selection strategies have serious limitations; however, they may explain in part the disproportionate number of HIV infections among Black MSM.

HIV transmission risk behaviours among HIV seropositive sexually transmitted infection clinic patients in Cape Town, South Africa

BACKGROUND

South Africa has one of the fastest growing HIV epidemics in the world and new infections may often result from people who have tested HIV positive. This study examined the sexual practices and risk behaviours of men and women living with HIV/AIDS being treated for a co-occurring sexually transmitted infection (STI).

METHODS

A sample of men and women receiving services at three South African STI clinics completed a computer administered behavioural assessment.

RESULTS

Among the 218 HIV positive STI clinic patients, 34 (16%) had engaged in unprotected vaginal or anal intercourse with uninfected or unknown HIV status sex partners in the previous month. A multivariate logistic regression indicated that unprotected sex with uninfected or unknown HIV status partners was independently associated with older age, female gender, alcohol use, and other drug use, and drug use in sexual contexts.

CONCLUSIONS

People living with HIV/AIDS who contract co-occurring STI are at significant risk for transmitting HIV to uninfected partners. Positive prevention interventions are urgently needed for South Africa.

HIV partner notification: predictors of discussion and agreements from provider reports

This study examines organizational, provider, client, and test-event level predictors of HIV partner notification (PN) discussion and agreements based on providers' most recent HIV-positive post-test counseling session. Staff (n = 621) were sampled from for-profit, nonprofit, and county government HIV testing organizations (N = 159) in Los Angeles County from 2003 to 2007. Among providers who conducted an HIV-positive post-test counseling session (n = 204), 65% discussed PN but only 10% had confirmed agreement to provider-involved PN (PIPN). In multi-level regression analyses PN discussion was predicted by provider HIV-test training and knowledge, and patients requesting a test while presenting HIV/AIDS symptoms. The strongest predictor of PIPN agreement was public health HIV testing settings followed by counseling by program managers or infectious disease specialists across settings. None of the injecting drug users or patients presenting with AIDS, but not requesting a test, agreed to PIPN. Organizational and provider-level interventions on PN will be needed to realize cost-effective benefits of expanded HIV testing and counseling.

HIV transmission risk among HIV seroconcordant and serodiscordant couples: dyadic processes of partner selection

Selecting sex partners of the same HIV status or serosorting is a sexual risk reduction strategy used by many men who have sex with men. However, the effectiveness of serosorting for protection against HIV is potentially limited. We sought to examine how men perceive the protective benefits of factors related to serosorting including beliefs about engaging in serosorting, sexual communication, and perceptions of risk for HIV. Participants were 94 HIV negative seroconcordant (same HIV status) couples, 20 HIV serodiscordant (discrepant HIV status) couples, and 13 HIV positive seroconcordant (same HIV status) couples recruited from a large gay pride festival in the southeastern US. To account for nonindependence found in the couple-level data, we used multilevel modeling which includes dyad in the analysis. Findings demonstrated that participants in seroconcordant relationships were more likely to believe that serosorting reduces concerns for condom use. HIV negative participants in seroconcordant relationships viewed themselves at relatively low risk for HIV transmission even though monogamy within relationships and HIV testing were infrequent. Dyadic analyses demonstrated that partners have a substantial effect on an individual's beliefs and number of unprotected sex partners. We conclude that relationship partners are an important source of influence and, thus, intervening with partners is necessary to reduce HIV transmission risks.

Changes in transmission risk behaviors across stages of HIV disease among people living with HIV

Advances in treatments for HIV infection and related opportunistic illnesses have significantly extended the life expectancy of people living with HIV. A review of the literature on HIV transmission risks among HIV-infected individuals shows patterns of risk behavior that vary according to HIV disease stage. Studies confirm that the period immediately preceding HIV infection is characterized by high rates of risk behaviors, indicating the potential for rapid spread of HIV during acute infection. Reductions in risk behavior are often seen immediately following an HIV diagnosis. However, these behavioral changes are not universal, and an individual's state of health is an important factor relating to transmission risks. Chronic periods of asymptomatic HIV infection are generally associated with some degree of reverting to risky behaviors. CD4 cell counts below 200 cells/mm(3), resulting in a formal diagnosis of AIDS, are associated with decreased sexual and drug-related risk behaviors. HIV risk reduction interventions for HIV-infected persons, therefore, require tailoring to address the health and psychological challenges individuals face as they progress through stages of HIV disease. Additional research on both risk behaviors of long-term HIV-infected persons and longitudinal data on risk behaviors is needed.

Identification of primary HIV-1C infection in Botswana

Methods for identification of primary HIV infections seem increasingly important to understand pathogenesis, and to prevent transmission, which is particularly efficient during acute infection. Most current algorithms for HIV testing are based on detection of HIV antibodies and are unable to identify early infections before seroconversion. The efficiency of prospective cohorts, which is a standard approach for identifying primary HIV-1 infection, depends on a variety of epidemiological and cultural factors including HIV incidence and stigma and, not surprisingly, varies significantly in different geographical areas. We report a voluntary counseling and testing (VCT)-based approach to identifying primary HIV-1C infection that was developed as part of a primary HIV-1 subtype C infection study in Botswana. The referral strategy was based on: (1) collaboration with VCT centers at city clinics operated by the Ministry of Health; (2) partnering with the busiest non-government VCT center; (3) educating healthcare workers and the community about primary HIV infection; and (4) pairing with diverse VCT providers, including NGOs and private-sector organizations. Acute HIV-1 infections were defined by a negative HIV-1 serology combined with a positive HIV-1 RT-PCR test. Recent HIV-1 infections were identified by detuned EIA testing according to the classic STARTH algorithm. The VCT-based referral strategy resulted in the successful identification of 57 cases of acute and early HIV infection. A referral strategy of expanded VCT with viral RNA (Ribonucleic acid) testing to a national program in Botswana may be a promising approach for identification of primary HIV infections on a countrywide level. The program should offer VCT with viral RNA testing to the general public, facilitate proper counseling and risk reduction, and allow initiation of early HAART, and may reduce new viral transmissions.

Inferring HIV transmission dynamics from phylogenetic sequence relationships

New insights into HIV transmission dynamics, say the authors, are likely to come from analyzing the viral sequence information that is being routinely collected during HIV genotyping.

Serosorting sexual partners and risk for HIV among men who have sex with men

OBJECTIVE

The purpose of the current study was to assess whether men who have sex with men (MSM) who limit their unprotected anal sexual partners to those who are of the same HIV status (serosort) differ in their risk for HIV transmission than MSM who do not serosort.

METHODS

Cross-sectional surveys administered at a large Gay Pride festival in June 2006 (80% response rate) were collected from MSM. Univariate and multivariate logistic regressions were used to identify predictors of serosorting. Analyses were conducted in 2006.

RESULTS

Participants were self-identified as HIV-negative MSM (N=628); about one third of them engaged in serosorting (n=229). Men who serosort were more likely to believe that it offered protection against HIV transmission, perceived themselves as being at no relatively higher risk for HIV transmission, and had more unprotected anal intercourse partners. Over half the sample reported their frequency of HIV testing as yearly or less frequently; this finding did not differ between serosorters and nonserosorters.

CONCLUSIONS

Men who identify as HIV-negative and serosort are no more likely to know their HIV status than men who do not serosort and are at higher risk for exposure to HIV. Interventions targeting MSM must address the limitations of serosorting.

Detection of Acute and Established HIV Infections in Sexually Transmitted Disease Clinics in Guangxi, China: Implications for Screening and Prevention of HIV Infection

BACKGROUND

Human immunodeficiency virus (HIV) has spread throughout China and to some degree has penetrated the general heterosexual population in some regions.

METHODS

A cross-sectional survey of 11,461 sexually transmitted disease (STD) clinic attendees in 8 cities in Guangxi, China, was conducted for syphilis and for acute and established HIV infections.

RESULTS

The prevalence of acute and established HIV infections was 1.2% among the participants. Five acute (preseroconversion) HIV infections were detected. Multivariate analysis showed that HIV infection was independently related to unmarried status (odds ratio [OR], 1.73 [95% confidence interval {CI}, 1.00-2.99), less education (OR for less than primary school, 4.21 [90% CI, 1.21-14.58]), residence in city A (OR, 11.48 [95% CI, 2.05-64.31]) or city B (OR, 7.93 [95% CI, 1.75-35.91]), working in the entertainment industry (OR, 3.98 [95% CI, 1.14-13.88]), injection drug use (OR, 25.09 [95% CI, 10.43-60.39]), no condom use during most recent sexual intercourse (OR, 4.97 [95% CI, 1.38-17.88]), and syphilitic infection (OR, 1.91 [95% CI, 1.03-3.56]).

CONCLUSIONS

HIV prevalence in STD clinics is significantly greater than that in the general population, and subjects were identified who would be missed by conventional surveillance. China's nationwide system of public STD clinics, which reach down to the township level, should be used for HIV control programs.

Diagnosis and management of acute HIV infection

HIV infection starts as an acute, systemic infection, followed by a chronic period of clinical latency, usually lasting 3 to 10 years, which precedes the eventual collapse of the immune system. It is increasingly recognized that events occurring during acute HIV infection may determine the natural course of the disease. The very dynamic events of acute HIV infection provide multiple opportunities for biologic interventions, such as anti-retroviral or immune-based therapies. Similarly, the implementation of public health measures during acute HIV infection could help control epidemics or outbreaks. Many of the dramatic possibilities for intervention in acute HIV infection remain unproved, not the least because of traditional difficulty of diagnosing patients during this early period. This article reviews the natural history, pathogenesis and clinical presentation of acute HIV infection, and suggests a diagnostic and therapeutic approach to guide clinicians dealing with patients with suspected or confirmed acute HIV infection.

Focusing HIV prevention on those most likely to transmit the virus

Despite some success in reducing HIV incidence, the global epidemic continues to grow. For every person with AIDS in developing countries placed on treatment in 2005, many others were newly infected. We need more effective prevention programs that focus interventions on those most at risk for HIV transmission (MART), particularly those with 1) high behavioral risk and 2) high viral loads due to acute or recent infection, co-infections with other diseases, high viral set points, or untreated AIDS. This article provides examples of how prevention programs can incorporate emerging testing technologies and social/behavioral approaches to reach these individuals, their partners, and the social networks where active transmission is occurring.

How many sexually-acquired HIV infections in the USA are due to acute-phase HIV transmission?

OBJECTIVE

To estimate the number of persons in the USA who acquire HIV as a consequence of risky sexual activities with an acutely-infected sex partner.

METHODS

Estimates of the number of incident infections in the USA that are due to acute-phase HIV transmission were derived from a simple mathematical model that combined epidemiological data with information regarding the relative transmission rates for acutely-infected, nonacutely infected but serostatus-unaware, and serostatus-aware persons living with HIV.

RESULTS

Approximately 2760 (8.6%) of the estimated 32 000 sexually-acquired HIV infections in the USA each year are due to acute-phase transmission of the virus. Multivariate sensitivity analyses with a liberal range of values for key parameters produced an upper bound of 5537 infections, representing 17.3% of the total number of sexually-acquired infections.

CONCLUSIONS

Acute-phase HIV transmission accounts for fewer sexually-acquired infections in the USA than is generally assumed.