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Keywords:

  • HIV prevention;
  • nonoccupational exposure;
  • post-exposure prophylaxis;
  • source tracing

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

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.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

The Victorian Non-Occupational Post Exposure Prophylaxis Service (VNPEPS) co-ordinates state-wide access to nonoccupational post-exposure prophylaxis (NPEP) for those exposed to HIV in the community. The central administration of the service is located at The Alfred Hospital in Melbourne, Australia and there are 18 sites throughout Victoria where NPEP can be accessed. Since the service began in August 2005 to 31 December 2010, most individuals (2053 of 3076; 67%) reported an exposure to a source partner whose HIV antibody (Ab) status was unknown. Based on an estimated HIV seroprevalence of 9.6% in men who have sex with men (MSM) in Melbourne, the majority of unknown source partners will be HIV negative and the exposed person will not require NPEP [1]. Australian NPEP Guidelines, as well as other international guidelines, recommend that a proactive attempt should be made to contact the source as an endeavour to reduce unnecessary NPEP prescriptions [2-4].

One Swiss study demonstrated a reduction in the number of NPEP prescriptions after the introduction of active source tracing. In 146 exposures, 76 involved a source whose HIV serostatus was unknown. Of these, NPEP was either avoided, or commenced and later ceased, in 31 patients (40.8%) when the source was contacted and tested negative for HIV [5]. A recently published study in a larger Swiss cohort produced similar findings. Over a 10-year period there were 910 requests for NPEP and the HIV status of the source was unknown in 702 cases. In 298 (42%) of these cases the source was identified and tested [6].

The VNPEPS promotes source tracing but in practice very few source partners are contacted and tested for HIV. Between August 2005 and March 2008, 877 of 1355 patients presenting for NPEP indicated that their source partner was of unknown HIV status. Of these, only 19 patients (2.2%) stopped NPEP after their source was found to be HIV Ab negative. In view of the success of the Swiss source-tracing study, the VNPEPS instituted a research study with the objective of increasing the number of source partners who could be contacted and tested. We hypothesized that the availability of rapid HIV testing, plus the option of a mobile testing service, would increase the likelihood of a source partner being contacted and agreeing to an HIV test, and thereby reduce unnecessary NPEP prescriptions.

Methods

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Patients presenting to the two busiest NPEP sites [the Melbourne Sexual Health Centre (MSHC) and The Alfred Hospital Emergency and Trauma Centre (AHE&TC)] 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. Ethics committee restrictions required the exposed person to contact the source directly, or the treating practitioner could contact the source on behalf of the exposed person only at the time of the consultation.

Results

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

Between 1 July and 30 November 2010, 168 eligible patients presented to the MSHC and The AHE&TC. Of these, 116 (69%) reported a source of unknown HIV status and 40 identified that they were able to trace their source. Despite this, no source individual was contacted and the study failed to enrol any participants. There were four patients at the MSHC who did stop NPEP after their source was found to be HIV Ab negative. However, this follow-up was done outside the study. At best, only four of 116 (3.4%; 95% confidence interval 0.9–8.6%) of NPEP prescriptions were avoided.

Discussion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

These are very different results from those reported by the Swiss study, which we were attempting to reproduce. Our hypothesis could not be addressed satisfactorily. Potentially there are a number of reasons for this.

First, the patient populations are different. Our cohort is predominantly MSM who have high-risk sexual exposures. In the Swiss cohort, the majority of requests for NPEP were by heterosexual individuals and only 15% of NPEP requests were for exposures in MSM [6]. MSM sources were also less likely than all other groups to be available for testing; 19% compared with nearly 50% or more in other groups [6]. Our results compare better with a San Francisco post-exposure prophylaxis (PEP) study where only 16% of individuals were able to identify a source, and the majority of these were HIV Ab-positive regular partners [7]. When the source's HIV Ab status was unknown, only 1.8% recruited their source within 4 days. In addition, women were more likely to recruit their source than men (23% compared with 8.5%) [7].

Secondly, the Swiss have a ‘PEP policy’. An Infectious Diseases resident is available ‘around the clock’ to assess the exposed person and to enquire about the source. If a phone number is available, the resident contacts the source directly. In the case of sexual exposure, the resident informs the source that there is also a benefit for them to be tested as they may have been exposed to HIV (from the patient who requested NPEP). To increase the rate of success, the resident also makes it clear that the test is free of charge for the source and anonymous (Gilbert Greub, University of Lausanne, Lausanne, Switzerland; personal communication). Our ethics committee did not give approval for the treating clinician to contact the source directly, except if during the consultation the exposed person were present. In addition, the HIV test result of the exposed person would often be available before the source was tested. This raises the question of whether it is ethical to tell the source that they are at risk too if the exposed person is already known to be HIV negative.

Finally, in Switzerland NPEP is paid for by the patient, with some reimbursement via medical insurance [6]. In Australia, NPEP is provided free of charge to exposed individuals. Thus, there is no monetary incentive involved in contacting the source and preventing or stopping NPEP. The benefits of source tracing for the exposed person perceived by our service, namely elimination of side effects, anxiety and the need for follow-up HIV testing, were not perceived as sufficiently beneficial to outweigh the discomfort of calling a casual partner to discuss HIV. It would seem that the combination of a predominantly MSM population, service model differences and the availability of NPEP free of charge in Australia makes the implementation of successful source tracing in Australia unfeasible.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References

The Victorian NPEP Service is funded by the Victorian Department of Health. No funding was received for this project.

Conflicts of interest: There are no conflicts of interest.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Methods
  5. Results
  6. Discussion
  7. Acknowledgements
  8. References
  • 1
    Pedrana A, Hellard M, Guy R et al. Sexual risk behaviour and knowledge of HIV status among a sample of gay men in Australia. 22nd Annual Conference of the Australasian Society for HIV Medicine. Sydney, Australia, 2010.
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  • 3
    Australian Government Department of Health and Ageing. National Guidelines for Post-Exposure Prophylaxis after Non-Occupational Exposure to HIV, 2007. Available at www.ashm.org.au/images/publications/guidelines/2007nationalnpepguidelines2.pdf (accessed 22 December 2011).
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    Roland ME, Martin JN, Grant RM et al. Postexposure prophylaxis for human immunodeficiency virus infection after sexual or injection drug use exposure: identification and characterization of the source of exposure. J Infect Dis 2001; 184: 16081612.