aNational Centre in HIV Social Research, and bNational Centre in HIV Epidemiology and Clinical Research, University of New South Wales, Sydney, NSW 2052, Australia.
Sponsorship: The National Centre in HIV Social Research and the National Centre in HIV Epidemiology and Clinical Research are supported by grants from the Australian government's Department of Health and Ageing.
Received: 11 December 2002; revised: 19 March and 23 April 2003; accepted: 20 May 2003.
Seventy-five homosexual men with recently acquired HIV were interviewed about their risk behaviour. Fifty-nine reported unprotected anal intercourse, and one shared injecting equipment, with a partner not known to be HIV negative. Of the remaining 15, 11 reported protected anal intercourse. In five of the 15 we judged oral sex to be the most likely source of infection, including three men who had a genital piercing. The possible transmission risk from genital piercing should be investigated.
Among homosexual men, unprotected receptive anal intercourse poses the highest risk of HIV transmission. Although it is agreed that the risk of transmission through oral sex is low, the precise degree of risk is difficult to establish [1–6] and sporadic cases have been reported .
Between 1993 and 1999, 75 homosexually active men in Sydney, with documented recent seroconversion, were interviewed in depth about the event(s) that may have led to their infection. A questionnaire schedule about all risk events in the previous 6 months was also administered. Transcripts were studied in detail and discrepancies discussed until investigators achieved consensus on each case.
To decide the most likely mode of transmission in each case we established a risk hierarchy. On the basis of epidemiological data, per-contact risk estimates and physiological plausibility [1,7–11], we assumed that sharing a needle for drug injection, unprotected receptive and insertive anal intercourse were high risk, and that condom-protected receptive and insertive anal intercourse, blood or semen contact with an open wound, oral sex and penile–anal external contact without insertion (`nudging') were medium to low risk. We regarded visits to dentists or blood donation in Australia, stepping on a discarded syringe, sex with a verified HIV-negative partner and mosquito bites as representing no risk. We adjusted in each case for the probability that the partner was infected, his likely viral load, timing in relation to any seroconversion illness, the presence of skin lesions, whether ejaculation occurred, and the length and vigour of the sexual act.
One man reported sharing injecting equipment with an HIV-positive partner. Fifty-nine men had had at least one episode of unprotected anal intercourse with an HIV-positive partner or one of unknown serostatus. Some of these men did not at first report brief or partial insertion as ‘intercourse', and regarded themselves as having had 100% safe sex. Some initially reported oral sex as their most likely source of infection. The remaining 15 men were judged to have acquired HIV through a less common route. Eleven of the 15 men also had protected anal intercourse, which they often assumed was 100% safe and did not report until questioned in detail.
We initially expected that the most plausible cases of oral transmission would be those involving receptive fellatio with ejaculation . However, in three of the five cases in which we judged oral transmission to be likely, insertive fellatio by a man with a penile piercing was the highest risk implicated. It is difficult to be certain that the risk pattern here is entirely a matter of the physical risk associated with a skin lesion rather than of the higher risk of exposure to positive partners, as the gay subculture of men involved in the leather scene, many of whom practise bondage and discipline and other esoteric sexual practices such as fisting, has a high proportion of HIV-positive men . Although aware that being pierced posed a risk of HIV or hepatitis C if the procedure was performed unhygienically, most men were unaware of any further risk once the initial wound had apparently healed.
Of the other two cases of likely oral transmission, one had no anal intercourse but receptive oral sex with ejaculation when he had gingivitis and dental treatment (open wound in mouth). The other had a single instance of condom-protected receptive anal intercourse with a man having anal sex for the first time, and multiple oral sex contacts with casual partners.
In studies attempting to quantify the risk of seroconversion associated with a particular sexual act, the ambiguity of some narratives would be seen purely as an obstacle to accuracy, or perhaps as a reason for excluding them from analysis. However, the apparently clear categories of questionnaire data do not remove such ambiguity but merely conceal it. Our in-depth interviews are likely to have elicited data that would not have been reported in a written questionnaire study. In one study, 55% of men who initially denied receptive anal intercourse in a written questionnaire later recalled it when they were interviewed . However, it is still possible that not all high-risk exposures were reported. Even a skilled interviewer cannot elicit a clear account of an event that is remembered through an emotional or drug-induced haze, or which was confusing to the respondent at the time. Definitions vary; a man who does not define fellatio or nudging as ‘sex’ will be unlikely to remember and report it. Reports of protected anal intercourse often emerged late in interviews when men had argued that their oral exposure was a more likely source of infection than their protected anal sex. Breaches in ‘safety protocol’ such as nudging or brief intromission without a condom were often ignored or concealed until probing questions were asked.
This case series cannot quantify the risk associated with oral sex. It is clear from the cohort and case–control studies that have analysed the risk that it is very low . Cohort studies of serodiscordant couples in whom sexual behaviour data are collected prospectively have not identified any cases of orogenital transmission [14,15]. Nevertheless, it is likely that cases of HIV transmission through unusual routes do occur.
Our participants were recruited through a network of general practitioners with high HIV caseloads. It is possible that men whose transmission route was uncommon were more likely to be referred to the study.
Among Sydney's gay and homosexually active men, condom use for oral sex has been neither recommended nor adopted since the advent of AIDS . Our findings suggest a need to investigate HIV transmission by breaches in skin integrity and to increase men's awareness of this issue. Body piercings, particularly of the genitals, may constitute a breach even when the skin has apparently healed on the surface, as the presence of a metal stud or ring may well cause ongoing subclinical inflammation . Furthermore, inflammatory skin conditions such as psoriasis can allow the entry of HIV, and are poorly recognized among gay men as constituting a potential site of entry for HIV. Dentists should explicitly warn patients about the infection risk associated with oral sex after performing invasive procedures or diagnosing gingivitis.
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