It should be noted that if you have herpes, you could be giving it to her. The transmission of herpes through cunnilingus if not just from the woman receiving, but also from the person giving.

Please also note that the picture provided is not the only clue to herpes. Herpes, like HIV is a virus, and is not always easily identifiable. In fact, how people react to herpes varies from person to person. Don't think you can identify someone with herpes just by a visual inspection!

anyone involved in biomedical research and medicine know that HIV and oral risk is theoretical at best. the only possible tinier than miniscule risks go to the ones that take cum in the mouth. Otherwise, it is close to zero. Receiving BJ is no risk unless she has OPEN LESION of herpes and syphgillis.
Herpes is not transmitted when it is not shedding - no lesions

you follow CDC recommendations for testing.  Also you minimize the risk of giving or receiving oral sex if you mean BBBJ or DATY by doing a couple of things that are emphasized by providers particularly London Rayne and Naomi_Sweets repeatedly day in and day out on these threads.

Rimming has more risk of contracting diseases that come from bacteria in the colon as well as parasites like Giardia but it can be mimmized hygeine prior at the rim.

Oral hygeine that minimizes STD transmission includes not brushing the teeth and gums for 2 hours prior and minimizing the use of antiseptic mouth washes which are less risk than vigorous brushing that can damage the integrity of the epithelium of the oral mucosa.

The following diseases while much lower risk than the other end of the spectrum could be transmitted if there were a break in integrity of the oral mucosa and/or cuts in the penis or scrotum area of the male or vulvar or clitoral (ouch) area of the female.  I'm not sure why previous posters chose to single out certain STDs as more prevelant in transmission under these circumstances, because the medical fact is any of them could be transmitted under the circumstances I outlined above.

We do threads on this nearly every other day by the way so if you read back on this board or the general board you can see scores of them.

Diseases that could theoretically be transmitted although you can minimize this by taking simple precautions to enjoy oral sex are:

HIV which has a winddow of a 4week to 6 month incubation period before it shows up in tests. By the way home testing will miss about 7% of HIV cases so it is never a test knowledgable physicians recommend or the medical/infectious disease literature recommends including the newest one available all over the web.
Herpes
Hepatitis B and Hepatitis C (right now we have no cure for C and it has a definite correlation to hepatocelluar carcinoma which is higher in heavy drinkers)
HPV which has a high correlation to cancer of the cervix in women particularly certain subtypes of HPV like 16.
Syphillis
Chancroid
Gonorrhea or GC
Chlamydia which is as high as 90% asymptomatic in females and 70% in males and currently is tested for about 45% of the population who has it in the US alone and has a 3 week incubation period before it shows up in tests.
Bacterial Vaginosis
Mulluscom Contagiosum
LGV (Lymphogranuloma Venereum) a subtype of Chlamydia

Also from this recent TER thread:
http://www.theeroticreview.com/discussion_boards/viewMsg.asp?BoardID=33&Page=1&MessageID=99863

When the mouth and tongue are healthy and uncut, the chance of getting a sexually transmitted infection (STI) through oral sex is quite uncommon, though possible. Sores or scrapes in the mouth present a ready passage-way for virus or bacteria to enter the blood stream. Unless you're 100 percent sure of your partner's clean bill of sexual health, it's a good idea to use protection if any cuts, tears, sores or scrapes are present in the mouth (even tiny sores, like accidentally biting your tounge). Additionally, after you've had your wisdom teeth yanked, a root canal performed, or your dentures re-fitted, it's wise to stay away from unprotected oral sex (even if your partner is STI-free, your dentist would probably advocate treating your mouth gently after any of these procedures).

STIs like gonorrhea, syphilis, Chlamydia, HPV, and HIV can be transmitted through pre-cum or ejaculate. Herpes, especially when cold sores are present, can also be passed on through oral sex. Although these cases are very rare, transmission is possible.

Good providers do care a great deal, and are attentive to staying as healthy as possible as Naomi conveyed.

However, I saw a blog from a top and expensive provider in my area who proudly bragged about having a chance pickup encounter on her blog where she cheerfully relished a male driving an uncondomed dick into her vagina.  So just because a provider is $500 an hour (if that story was true that she proudly blogged about recently) doesn't mean they are particularly safe in all their sex practices. And that particular male plunging his uncondomed dick into her after a chance pickup has probably plunged same uncondomed dick into other vaginas or other additional closed spaces like a rectum.

See Also:
HIV Transmission from CDC
http://www.cdc.gov/hiv/resources/qa/transmission.htm

Ck out the Topic (Expand the plus) "Can I get HIV from Oral Sex?"

CDC-INFO STDs
1-800-CDC-INFO (232-4636)