syphilis from oral sex

I was looking for some reliable information. What are the chances or percentage of a man catching syphilis from an infected woman by performing cunnilingus on her? Secondly, what are the percentage of people who are infected with syphilis that never develop any primary or secondary symptoms?

[H. Hunter Handsfield, M.D.]

I doubt there has been a single case of syphilis acquired by performing cunnilingus in the past 10 years in the United States.  Why?  One reason is that there aren't very many infected women, outside rather restricted population groups (two thirds of all cases occur in gay men).

The proportion of people with newly acquired syphilis who remain asymptomatic depends on the site of exposure.  It is hard to miss a chancre of the penis or mouth, but easy to miss one inside the rectum or vagina.  The chance someone could catch syphilis of the mouth and not notice anything wrong probably is well under 10%.  The symptoms of secondary syphilis can be subtle, however.  But considering all people with newly acquired infection probably at least 80% would have symptoms of primary or secondary syphilis.

Assuming this all applies to you, it seems you have little reason to worry about syphilis.  But if this reassurance doesn't completely resolve your fears, have a syphilis blood test about 6 weeks after the exposure.

I hope this helps.  Best wishes--- HHH, MD

[cdn067]

The reason I asked were that the women were in a high risk group (escorts), and I used protection except for that act.

[H. Hunter Handsfield, M.D.]

Contrary to what you assume, many commercial sex workers are not at particularly high risk for most STDs or HIV.  The frequency of syphilis in escorts (i.e., more expensive CSWs) probably is very low, especially in those who routinely use condoms for vaginal and anal sex, as yours apparently does.  My estimate above of the likelihood of someone acquiring syphilis by cunnilingus applies to you.  You aren't likely to be the first such case in recent years, especially in the absence of a lesion of your lips or tongue that you would notice.