Two Cases Document AIDS Transmission Through Oral Sex

The San Francisco Department of Public Health has documented what are apparently the first two cases in California of AIDS virus transmission between two men through oral sex.

The researchers said the new data confirm other reports of transmission of the human immunodeficiency virus, or HIV, through oral sex and reinforce earlier warnings from public health officials that the practice does not represent safe sex.

“Exposure to semen, whether oral, vaginal or rectal, carries a risk of transmission of HIV,” Dr. Alan R. Lifson, assistant director for research of the department’s AIDS office, said in a telephone interview Saturday. Lifson added that although oral sex may be “less risky” than anal intercourse as a means of transmitting the AIDS virus, it is “not safe.”

Public health officials emphasize several strategies to avoid exposure to the AIDS virus through sexual intercourse. These include using condoms, avoiding the exchange of bodily fluids, such as semen, and abstaining from sexual relations.

The AIDS virus is contained in the semen, as well as the blood, of infected individuals. The virus might be transmitted to a sexual partner during oral intercourse through small cuts or sores in the mouth, diseased gums or normal oral tissue. Researchers, however, are not certain of the exact means of transmission.

Lifson said he was “confident” of the findings in the two “very recent” cases. Both men had only one risk factor for HIV infection--exposure to semen through receptive oral intercourse.

The two men had been studied extensively over the last five years as part of a citywide San Francisco study of thousands of gay and bisexual men.

In the previous studies, the two men had tested negative for AIDS virus antibodies. This summer, they both tested positive. A test known as the polymerase chain reaction, which is a more sensitive blood test than the standard antibody test, confirmed that the earlier AIDS antibodies tests were negative, Lifson said.

Detailed sexual and personal histories revealed that one man had receptive oral sex with multiple partners whose HIV infection status was unknown. The other man also had oral sex with multiple partners, one of whom was known to be infected with HIV.

“The interviewers . . . were quite confident that the information they received was accurate,” Lifson said.

There have been several earlier reports in medical journals describing apparent cases of HIV transmission between two men through oral sex. In September, 1987, Boston researchers reported such a case in the Annals of Internal Medicine.

In January, Massachusetts researchers described a case of apparent female-to-male transmission of the AIDS virus through oral sex. But the reliability of the report, which was published as a letter in the New England Journal of Medicine, was questioned by other AIDS physicians.