###Human: What are the chances of acquiring a HIV infection from a used, hair-cutting blade? ###Assistant: Hello. The likelihood of HIV (human immunodeficiency virus) transmission, in this case, is 1 in 300. Firstly, you are not sure that the person, on whom the blade was used previously, was HIV positive. More importantly, HIV rarely survives in dried blood. So, in the case the person's blood was on the blade, it would have dried in 15 minutes. Hence it is less likely that the HIV would survive. In spite of all this, I would say precaution is the best. Always ask the barber to use a new blade. Also, the chances of getting a Hepatitis B and C infection are higher than that of an HIV. To prevent this, I suggest getting a Hepatitis B vaccine. Please consult your local clinic in case you experience any unexplained and non-recovering fever. If you are still worried, consult your local clinic and get an HIV test done after one to three months. For more information consult an internal medicine physician online -->