Just how risky are various activities for transmission of HIV?
The CDC in the US has published what they believe to be the best estimates of the risk of transmission of HIV by a variety of activities. They are indicated in the images below. The risks are listed as the risk per 10,000 exposures, as well as by odds.
You need to keep in mind that the risks are increased in sexually transmitted routes if there is some other sexually transmitted infection (STI) present. If you have gonorrhea, for example, the inflammation that causes decreases the natural barriers of your mucous membranes, and thereby increases the likelihood of transmission of HIV. If the positive partner has an STI, then the inflammatory cells in their system that are fighting that infection carry HIV and when they are transmitted during sex, a higher load of HIV is transmitted.
In the case of needlestick injuries, the age of the blood in the needle is important. Fresh blood from one person to another, such as in transfusion is highest risk, while a needle with dried blood found on the ground and then causing a needlestick injury, is much less of a risk. Keep in mind that other infections, such as hepatitis C, are transmitted through dried blood, so the risk of transmission of hepatitis C is the same whether the blood on the needle is fresh of dried.
Thank you to Blue Ranger Design for the graphics.
Estimate of per-act risk for acquisition of HIV by exposure route, assuming no condom use. | |
Exposure Route | Risk per 10,000 Exposures - (Odds) |
Blood Transfusion with Contaminated Blood 9,000 - (9 out of 10) | |
Needle-Sharing Injection Drug Use 67 - (6.7 out of 1,000) | |
Anal Sex Positive Person on Top 50 - (5 out of 1,000) | |
Vaginal Sex Negative Female 10 - (1 out of 1,000) | |
Anal Sex Negative Male on Top 6.5 - (6.5 out of 10,000) | |
Vaginal Sex Negative Male 5 - (5 out of 10,000)
| |
Oral Sex Negative Male Performing 1 - (1 out of 10,000) | |
Oral Sex Negative Male Receiving 0.5 (5 out of 100,000) |
