Oral sex between men a ‘small but real risk’ for HIV transmission, survey shows

Christopher Gadd
Published: 05 August 2004

Oral sex probably acounts for almost 3% of HIV infections in men who have sex with men (MSM), according to the results of a survey of newly diagnosed patients in England, Wales and Northern Ireland. This finding is published in a letter in the 1st August issue of Sexually Transmitted Infections.

The risk of contracting HIV through oral sex is known to be low. However, there is uncertainty surrounding the precise degree of risk due to the difficulty in obtaining reliable reports from study participants and differences between study findings, with estimates of incidence varying from less than 1% to almost 7% in one American study. “The indication given by these UK surveillance data is that oral sex carries a small but real risk,” write the authors.

The investigators, from the Communicable Disease Surveillance Centre in London, collated information from the 4150 MSM diagnosed with HIV between July 2001 and September 2003. The reports for 1359 of these men contained the question “Does the patient believe himself to have been infected through oral sex?”

Of the 688 (51%) of the patients who answered this question, 625 (91%) said ‘no’, while 63 (9%) said ‘yes’. However, on further questioning by a clinician or healthcare worker, 27 (43%) of the patients saying ‘yes’ admitted to having had unprotected anal intercourse, while 16 (25%) reported that oral sex was their only risk factor for having acquired HIV. The remaining 20 patients (32%) reported protected anal sex, but unprotected oral sex.

Assuming that infection did not occur through oral sex in the 671 cases for whom the answer to the question was not recorded, the authors calculate that “2.6% (36 of 1359) were probably infected through this route.” However, the true incidence of HIV transmission due to oral sex may be lower than this value, due to shame, denial or willingness to please the clinician or healthcare worker.

Although the study did take the HIV status of their partners into account, the patients were not asked about whether ejaculation occurred in the mouth, or whether there were small cuts or abrasions in the mouth, both of which could increase the risk of HIV transmission.

In addition, the authors acknowledge that “there may be recall difficulties surrounding condom use … or if used, coming off or splitting, or brief anal-penile contact that was not considered relevant or remembered.” The letter does not include any information on the prevalence of other sexually transmitted infections around the suspected time of HIV infection.


Gilbart VL et al. HIV transmission among men who have sex with men through oral sex. Sex Transm Infect 80: 324, 2004.

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