My wife and I enjoy oral sex. However, we have recently become concerned about the possibility of oral transmission of candidiasis, bacterial vaginosis, etc. I know that HIV and herpes can be transmitted this way, but we don't know about bacteria and fungi.

Ross

Oral sex can transmit infection. That said, a couple involved in a monogamous relationship has little to worry about. As you stated, herpes and HIV (the virus that causes AIDS) can both be spread by oral sex. If a person has oral herpes (cold sores) he or she can pass the infection to his/her partner. The recipient can then develop full-blown genital herpes. This can also occur in the reverse, when performing oral sex on a partner who has genital herpes leads to a case of oral herpes. A recent medical study confirmed that herpes could be spread even when there are no visible lesions.

HIV can also be spread by oral sex. This is thought to be less common than spread by sexual intercourse, but previous reports stating that HIV is only rarely spread by oral sex were probably understating the case. Other viruses that could possibly be spread through oral sex include hepatitis B, hepatitis C and cytomegalovirus (CMV). Hepatitis B is commonly spread through sexual intercourse and is presumed to be spread by oral sex. Hepatitis C is less commonly spread through sex, but it is possible. CMV, while not commonly thought of as a sexually transmitted disease, can be spread in this manner.

Other STDs (sexually transmitted diseases) can be spread orally. Syphilis commonly makes itself evident with a chancre or sore on the genitals, but if acquired through oral sex, the lesion can appear in the mouth. Gonorrhea can cause throat infection after oral sex. Chancroid, a painful ulcerative lesion, can also in rare cases occur on the mouth. Human papillomavirus (HPV), the cause of genital warts, can cause infections in the mouth as well. Experts have some concern that oral infections of this type may predispose people to cancer of the mouth and larynx (voice box), much as certain strains of HPV predispose women to cervical cancer.

The infections you mention, candidiasis (yeast) and bacterial vaginosis, are not likely to be transmitted by oral sex. In fact, they are generally not thought of as sexually transmitted diseases at all. Several medical-research studies have shown that treating the male partners of women with bacterial vaginosis has no significant effect on the recovery or relapse rate in patients with this syndrome. Similar studies have been performed for vaginal yeast infections, and the results have been largely inconclusive. I would not worry about bacterial vaginosis and yeast infections with regard to oral sex.

I can summarize the infection risk of oral sex in this way: Most diseases that can be transmitted by sexual intercourse can also be transmitted by oral sex. But if you are in a mutually monogamous relationship with someone who is free of disease, there is not much to worry about.