Postexposure prophylaxis for human immunodeficiency virus infection after sexual or injection drug use exposure: identification and characterization of the source of exposure

Nonoccupational post-exposure prophylaxis source tracing: is it really feasible in Australia?

OBJECTIVE

A Swiss nonoccupational post-exposure prophylaxis (NPEP) source-tracing study successfully reduced unnecessary NPEP prescriptions by recruiting and testing source partners of unknown HIV serostatus. The Victorian NPEP Service in Australia attempted to replicate this study with the addition of HIV rapid testing and a mobile service.

METHODS

Patients presenting to two busy NPEP sites who reported a source partner of unknown HIV status were routinely asked if their source could be traced. If the exposed person indicated that their source partner was traceable they were asked to contact them and discuss the possibility of having an HIV test.

RESULTS

No sources were enrolled and the study was terminated.

CONCLUSION

We hypothesize that there are a number of differences between Australia and Switzerland that make source tracing unfeasible in Australia.

Strategies for harm reduction among HIV-affected couples who want to conceive

As effective HIV treatments become more widespread, HIV-infected individuals are living longer, healthier lives. Many HIV-affected couples (sero-discordant and sero-concordant) are considering options for safer reproduction. A large body of evidence suggests that reproductive technologies can help HIV-affected couples to safely conceive with minimal risk of HIV transmission to their partner. However, for most couples such technologies are neither geographically nor economically accessible. This paper addresses the options for safer procreation among HIV-affected couples who cannot access reproductive technologies.

Tenofovir DF plus lamivudine or emtricitabine for nonoccupational postexposure prophylaxis (NPEP) in a Boston Community Health Center

BACKGROUND

Nonoccupational postexposure prophylaxis (NPEP) has been used to decrease HIV transmission after high-risk exposures. However, suboptimal adherence in completing the recommended 28-day course has resulted in prophylaxis failures. Fenway Community Health, the largest center caring for HIV-infected and high-risk men who have sex with men (MSM) in New England, began an NPEP program in 1997, initially using zidovudine-based regimens.

METHODS

Two phase 4 studies, using tenofovir DF regimens combined with either lamivudine or emtricitabine, were conducted. This paper evaluates the experience of those who used tenofovir-based NPEP regimens, comparing the subjects to historical controls who used zidovudine-containing regimens.

RESULTS

Between May 2004 and March 2005, 44 individuals who presented after high-risk sexual exposure were prescribed tenofovir DF/lamivudine for NPEP. Between March 2005 and March 2006, 68 individuals with 72 high-risk experiences received tenofovir DF/emtricitabine, and were compared to122 historical controls who were prescribed 126 courses of zidovudine plus lamivudine between January 2000 and May 2004. Seventy-two percent of those who took tenofovir DF and emtricitabine, and 87.5% of the participants who took tenofovir DF and lamivudine, for NPEP completed their regimens as prescribed, whereas only 42.1% of those who took zidovudine plus lamivudine did so (P < 0.0001). Participants who took tenofovir DF-containing regimens were more likely to report diarrhea or abdominal discomfort; patients who took zidovudine-containing regimens were more likely to report nausea and vomiting, which was often severe enough to lead to product discontinuation.

CONCLUSIONS

Tenofovir DF-containing regimens for NPEP are generally well tolerated with high completion rates. Tolerability and adherence compared favorably to zidovudine-containing regimens used previously. Tenofovir DF-containing regimens should be considered for PEP to enhance adherence and regimen completion.

The public health impact of widespread availability of nonoccupational postexposure prophylaxis against HIV

OBJECTIVE

The aim of the study was to describe the use of nonoccupational postexposure prophylaxis (NPEP) in Australia, and to estimate the number of HIV infections that its use prevented.

METHODS

We conducted a population-based observational cohort study of people who presented to antiretroviral prescribers in Eastern Australia, and reported a high-risk nonoccupational exposure to HIV, in 1998-2004. Prescribers collected data at baseline, 4 weeks and 6 months. Data collected included details of HIV exposure, drug regimens and HIV serostatus.

RESULTS

The great majority of the 1601 participants were male (95%) and presented after male homosexual exposure (87%). Only 32% of exposures were to HIV-positive sources. Two antiretroviral drugs were prescribed after 48% of events, and three or more drugs after 52% of events. The median time to receipt of NPEP was 23 h. Side effects were reported by 66% of participants. No case of NPEP failure in an adherent individual was identified. It was estimated that 0.9-9.2 HIV infections had been prevented. This compared with a total of 1138 newly acquired HIV infections notified in the geographical area covered by the study.

CONCLUSIONS

In Australia, NPEP has been widely prescribed and is mainly targeted at high-risk exposures. Although there were no identified failures of NPEP, it is likely that only a small proportion of new HIV infections in the study area were prevented. NPEP may be a valuable preventive intervention for an individual, but it can only play a minor role in HIV prevention at the population level unless targeting can be further improved.

Postexposure prophylaxis after sexual exposure to HIV

Increasing numbers of international, national and state/provincial health organizations in the developed and developing world recommend postexposure prophylaxis (PEP) following potential sexual exposure to HIV. The evidence for these policies is extrapolated from occupational healthcare worker, perinatal prophylaxis and animal studies. There is no direct evidence of PEP efficacy after sexual exposures. Studies addressing potential increases in risk behavior, toxicities and cost–effectiveness are encouraging. Considerations for offering PEP include the timing and characteristics of the exposure and the HIV status of the source and exposed individuals. PEP includes 28 days of a combination antiretroviral drug regimen containing two or more drugs and associated laboratory testing, counseling and referrals. PEP service delivery challenges include ensuring adequate access to services, optimizing PEP adherence and facilitating follow-up HIV testing and counseling. Men who have sex with men, sexual assault survivors, children and adolescents, and individuals in resource-limited settings present unique needs and challenges.

Cost-effectiveness of HIV post-exposure prophylaxis in France

OBJECTIVE

To assess the cost-effectiveness of HIV post-exposure prophylaxis (PEP) in France.

METHODS

We used a decision tree to evaluate, from a society's perspective, the cost of PEP per quality-adjusted life-year (QALY) saved. We used 1999-2003 PEP surveillance data and literature-derived data on per event transmission probabilities, PEP efficacy and quality of life with HIV. HIV prevalence and lifetime cost of HIV/AIDS management in the HAART era were derived from French studies. We assumed that mean life expectancy in full health was 65 years among uninfected individuals and that the mean survival time after HIV infection was 22.5 years. The costs of PEP drugs and follow-up were derived from the French public sector. A 3% annual rate was used to discount future costs and effects.

RESULTS

During 1999-2003, PEP was prescribed to 8958 individuals (heterosexual sex: 47.6%; homosexual sex: 28.4%; occupational exposure: 23.4%; drug injection: 0.6%); of those, 2143 were exposed to a known HIV-infected source. PEP was estimated to prevent 7.7 infections and saved 64.5 QALY at a net cost of euro 5.7 million, resulting in an overall cost-effectiveness ratio of euro 88,692 per QALY saved. PEP was cost saving for 4.4% of cases and cost effective (< euro 50,000 per QALY) in a further 11.3% of cases. In contrast, 72 and 52% of prescriptions had a cost-effectiveness ratio exceeding euro 200,000 and euro 2 millions, respectively, per QALY saved.

CONCLUSION

Overall, the French PEP programme is only moderately cost effective. PEP guidelines should be revised to target high-risk exposures better.

Seroconversion following nonoccupational postexposure prophylaxis against HIV

BACKGROUND

The efficacy of antiretroviral postexposure prophylaxis (PEP) against infection with human immunodeficiency virus (HIV) following occupational exposures has prompted the use of PEP after nonoccupational exposures. There are, however, important differences between occupational and nonoccupational exposures, and the effectiveness of PEP following nonoccupational exposure is unknown. We sought to describe the occurrence and circumstances of HIV seroconversion following nonoccupational PEP.

METHODS

HIV uninfected individuals reporting potential sexual or injection drug use exposures to HIV in the preceding 72 h received a 28-day regimen of antiretroviral therapy and counseling in a nonrandomized trial. The level of HIV antibody was measured 12 weeks after PEP initiation.

RESULTS

Of 877 exposed subjects, 702 were evaluable 12 weeks after exposure. Seroconversion was detected in 7 subjects (1%; 95% confidence interval, 0.4%-2%). Three seroconverters reported having no exposures after PEP initiation and, thus, probably represent evidence of chemoprophylactic failure. In the other 4 subjects, additional exposures to HIV after PEP initiation or detection of HIV RNA in plasma specimens obtained at baseline precluded determination of the source of seroconversion. No exposure source was available to assess genetic concordance with the seroconverter's virus.

CONCLUSIONS

As for occupational exposure, PEP is not completely effective in preventing HIV infection following nonoccupational exposure. Therefore, primary prevention remains essential. In contrast to the occupational setting, the potential source of exposure is rarely available for testing in the nonoccupational setting, and exposures are often not isolated. Thus, it is often impossible to determine whether seroconversion resulted from failure of PEP or from other exposures, posing difficulties for future comparative studies seeking to evaluate the effectiveness of PEP.

Current trends of HIV disease of the mouth

HIV infection affects residents of all countries of the world, but the greater majority of affected individuals reside in the developing world. In the past decade there have been substantial changes in the management of HIV disease, particularly the introduction of highly active antiretroviral therapy (HAART). Such agents have reduced significantly the morbidity and mortality associated with HIV disease, however, they are not available for most HIV-infected individuals in the developing world. There is now considerable understanding of the molecular epidemiology, transmission and therapy of the common opportunistic oral infections of HIV disease, and as a consequence of improved anti-HIV strategies, the frequency and severity of oral disease associated with HIV infection have reduced considerably, although HAART may predispose to human papilloma virus infection of the mouth and potentially increase the risk of later oral squamous cell carcinoma. Despite advances in clinical care the majority of individuals with HIV disease worldwide will continue to develop oral disease, as they are resident in the developing world and do not have ready access to even simple therapies.

Postexposure Prophylaxis After Sexual Assaults: A Prospective Cohort Study

OBJECTIVE

The objective of this study was to evaluate HIV postexposure prophylaxis (PEP) protocol in rape victims.

STUDY

The victims were assigned to 1 of 3 categories, according to the severity of exposure (I-low, II-moderate, III-high). HIV PEP was provided to victims in groups II (Zdv + 3TC) and III (Zdv + 3TC + PI) until 72 hours after exposure. The follow-up was 6 months.

RESULTS

From May 1997 to October 2001, 347 victims were attended. PEP was offered to 278 victims (141 in group II and 137 in group III). Side effects were more common in group III (P <0.01). No seroconversion was diagnosed in the 180 victims that completed the follow-up. Univariate analysis showed that the schooling level, knowledge of the aggressor's HIV status, and the use of PEP were associated with compliance.

CONCLUSIONS

Triple therapy was associated with side effects, which suggested that drug regimes should be reviewed. The variables related to a high risk of HIV transmission were also significant for compliance.

Potential effect of HIV type 1 antiretroviral and herpes simplex virus type 2 antiviral therapy on transmission and acquisition of HIV type 1 infection

Biological strategies for interrupting transmission of human immunodeficiency virus (HIV) type 1 should be directed at reducing infectiousness of and susceptibility to HIV-1. Potential antiretroviral interventions include reducing the likelihood of transmission of HIV-1 by reducing HIV-1 load in the blood and genital tract of HIV-1--infected person, prophylaxis after high-risk exposure, and pre-exposure prophylaxis for very high risk populations. Antiviral treatment of herpes simplex virus (HSV) type 2, the most common cause of genital ulcers, should be evaluated as a strategy for HIV-1 infection prevention by reducing infectiousness of and susceptibility to HIV-1, on the basis of biological and epidemiological data indicating that HSV-2 facilitates transmission and acquisition of HIV-1. The rationale for antiretroviral and HSV-2-specific interventions and studies to test these strategies are described.

The antiretroviral rollout and drug-resistant HIV in Africa: insights from empirical data and theoretical models

The U.S. Government has pledged to spend $15 billion in Africa and the Caribbean on AIDS. A central focus of this plan is to provide antiretroviral treatment (ART) to millions. Here, we evaluate whether the plan to rollout ART in Africa is likely to generate an epidemic of drug-resistant strains of HIV. We review what has occurred as a result of high usage of ART in developed countries in terms of changes in risky behavior, and the emergence and transmission of drug-resistant HIV. We also review how mathematical models have been used to predict the evolution of drug-resistant HIV epidemics. We then show how models can be used to predict the likely impact of the ART rollout on the evolution of drug-resistant HIV in Africa. At currently planned levels of treatment coverage, we predict that (over the next decade) in Africa: (i) the impact of ART on reducing HIV transmission (and prevalence) is likely to be undetectable (unless accompanied by substantial changes in behavior), (ii) the transmission rate of drug-resistant HIV will be below the WHO surveillance threshold of 5%, and (ii) the majority of cases of drug-resistant HIV that will occur will be due to acquired (and not transmitted) resistance. For the next decade, large-scale surveillance for detecting transmitted resistance in Africa is unnecessary. Instead, we recommend that patients should be closely monitored for acquired resistance, and sentinel surveillance (in a few urban centers) should be used to monitor transmitted resistance.

Management of occupational and nonoccupational postexposure HIV prophylaxis

The principles of managing patients with recent HIV exposures are similar whether the exposure occurs in an occupational or nonoccupational setting. For both settings, clinicians should 1) assess the likelihood that HIV and other bloodborne viruses will be transmitted as a consequence of the exposure; 2) advise the patient about the risks and benefits of treatment; 3) choose an appropriate antiretroviral treatment regimen (if the decision is made to treat); 4) screen for other illnesses that may complicate treatment or follow-up; 5) counsel patients about the importance of adhering to treatment; 6) promote safe-sex practices and methods to avoid future exposures; 7) follow the patient for potential side effects of treatment; 8) provide follow-up care including repeat HIV testing for seroconversion, surveillance for primary HIV infection, and reinforcement of counseling messages.

Cost-effectiveness of HIV postexposure prophylaxis following sexual or injection drug exposure in 96 metropolitan areas in the United States

OBJECTIVES

To evaluate the cost-effectiveness of HIV postexposure prophylaxis (PEP) following sexual or injection-related exposures in 96 metropolitan statistical areas in the United States (MSA).

DESIGN

Empirical, model-based cost-effectiveness analysis.

METHODS

Epidemiological and population size estimates from the literature were combined with information about the distribution of exposure types, PEP completion rate, proportion of source partners known to be HIV infected, and PEP program costs obtained from a feasibility study of PEP in San Francisco to estimate the cost-effectiveness of hypothetical PEP programs in each of the 96 MSA. The effectiveness of combination antiretroviral therapy following sexual or drug use-related exposures, which is presently not known, was assumed equal to the effectiveness of zidovudine monotherapy in the occupational setting. The main outcome measure was the cost-utility ratio, defined as the cost per quality-adjusted life year (QALY) saved by the PEP intervention.

RESULTS

The cost-utility ratios for the 96 MSA ranged from 4137 dollars to 39,101 dollars per QALY saved; only two of the ratios exceeded 30,000 dollars per QALY saved. Combined across the 96 MSA, the hypothetical PEP programs would reach nearly 20,000 clients at a total cost of approximately 22 million dollars. The overall cost-utility ratio across MSA was 12,567 dollars per QALY saved. The majority of the HIV infections prevented by PEP were among men and women who reported receptive anal intercourse exposure.

CONCLUSIONS

PEP following sexual or drug use-related exposures could be a cost-effective complement to existing HIV-prevention efforts in most MSA across the United States.

Transmission of HIV-1 drug resistance

BACKGROUND

The use of highly-active anti-retroviral therapy (HAART) for treating HIV infections is increasing. Recent studies have demonstrated that HAART is improving both the length and quality of life in HIV-infected patients. Resistant strains of HIV arise when drug adherence is poor. This can lead to the transmission of drug-resistant strains of HIV to susceptible individuals. This can lead to suboptimal first-line therapy, if the resistance profile of the transmitted virus is unknown.

OBJECTIVES

To review the mechanisms of how drug resistance arises; the methods used to characterise drug resistance; the problems arising with compliance leading to the development of drug-resistant HIV strains; the evidence for the incidence, prevalence and trends in the transmission of resistant HIV strains in different risk groups; and the evidence of suboptimal response to first-line therapy where transmission of a resistant HIV strain has occurred. On the basis of this, a case is presented for the routine resistance testing of all newly diagnosed HIV-infected individuals.

STUDY DESIGN

Literature review.

RESULTS AND CONCLUSIONS

There is evidence, though limited at present, that transmission of drug-resistant HIV strains can lead to suboptimal response to first-line therapy in newly diagnosed HIV-infected individuals. As the use of HAART can only increase in the future, and compliance will always be a problem in such HAART-treated patients, baseline resistance testing should become a routine part of their management.

Human immunodeficiency virus type 1 superinfection was not detected following 215 years of injection drug user exposure

Evidence for human immunodeficiency virus type 1 (HIV-1) superinfection was sought among 37 HIV-1-positive street-recruited active injection drug users (IDUs) from the San Francisco Bay area. HIV-1 sequences from pairs of samples collected 1 to 12 years apart, spanning a total of 215 years of exposure, were generated at p17 gag, the V3-V5 region of env, and/or the first exon of tat and phylogenetically analyzed. No evidence of HIV-1 superinfection was detected in which a highly divergent HIV-1 variant emerged at a frequency >20% of the serum viral quasispecies. Based on the reported risk behavior of the IDUs and the HIV-1 incidence in uninfected subjects in the same cohort, a total of 3.4 new infections would have been expected if existing infection conferred no protection from superinfection. Adjusted for risk behaviors, the estimated relative risk of superinfection compared with initial infection was therefore 0.0 (95% confidence interval, 0.00, 0.79; P = 0.02), indicating that existing infection conferred a statistically significant level of protection against superinfection with an HIV-1 strain of the same subtype, which was between 21 and 100%.