Primary HIV Infections Associated with Oral Transmission
B. DILLON*1, F. M. HECHT2, M. SWANSON2, I. GOUPIL-SORMANY2, R. M. GRANT3, M. A. CHESNEY4, and J. O. KAHN2.
1CDC, Atlanta GA; 2San Francisco Gen. Hosp. and Univ. of California, San Francisco; 3Gladstone Inst. of Immunology and Virology, San Francisco; and 4Ctr. for AIDS Prevention Studies, Univ. of California, San Francisco
Objective: To investigate reported cases of oral HIV transmission in a cohort of persons with primary HIV infection
Methods: From 6/96 - 6/99 we enrolled 122 persons with primary HIV defined as within 12 months of documented HIV seroconversion or history compatible with primary HIV infection confirmed by less sensitive EIA test. Risk behaviors for the period during which infection occurred were elicited with self-administered and interviewer administered questionnaire. Potential oral sex transmission cases were reviewed following an investigation protocol of a follow-up interview by an epidemiologist, review of clinical notes and partner corroboration where possible.
Results: There were 20 (16.4%) cases where the route of acquistion appeared to be oral sex on initial evaluation. Of these 20 cases, 3 provided insufficient additional information for classification. Of the remaining 17, 9 (53%) were subsequently reclassified as not associated with oral transmission due to other potential route of exposure. Two reclassified patients reported never engaging in anal sex but each reported a single episode of substance use associated with a blackout and risk could not be reliably recalled. Four patients reported a single incident of unprotected anal receptive anal intercourse and 1 reported a condom break during the period HIV was acquired. After follow-up investigation, 8 cases (6.6%) were classified as likely oral sex transmission. Each of the men believed oral sex represented no or minimal risk.
Conclusion: Oral sex transmission may be over-reported. However, even with strigent criteria for classification, oral risk transmission represented 6.6% of infections in our study of primary HIV. Despite lower transmission risk, oral sex may be an important mode of HIV transmission due to its frequency. This finding has substantial prevention implications. Standardized investigation of HIV transmission via oral sex is needed to understand the epidemiology and risk of this behavior.
Key Words: Oral Sex, Primary HIV, Transmission Risk