Q: Hello good evening Doc. My question goes like this; if a person is HIV positive, and then he cuts him/her with a blade, after 3days anther person uses da same Sharp object, and her also cuts him/herself with the same blade while the Blood is dry… How true is it that, if the Blood has dried out that u cannot get infected?
A: Thanks for writing in.
Once the blood on a blade is exposed to air, it dries out and because the Human Immuno-deficiency Virus is just too fickle, it dies very quickly and loses its ability to divide and multiply outside the human body. So, it is unlikely that using same blade 3 days later will lead to infection with the HIV.
Having said that, my first advice would be to get tested immediately if you believe you have been exposed to risky behavior. Post exposure prophylaxis may be recommended by your doctor. These drugs used to treat HIV are usually taken daily for about 4 weeks to reduce chances of becoming HIV positive.
The length of time before a subject tests positive to HIV following exposure (sero-conversion), known as the window period would depend on the type of test done.
An antibody test can read positive from 3 to 12 weeks, if there is sero-conversion. An antibody is a disease-fighting protein produced by the body in response to an infection (HIV infection, in this case).
A combination antibody/antigen test (which detects both antibody and antigen…which is a part of the virus) can read positive from 2 to 6 weeks after exposure, if there is sero-conversion.
A Nucelic Acid Test (NAT) can detect HIV infection in the blood from 7 to 28 days following infection.
Generally, if the initial test is negative, a repeat test is done 3 months after the exposure to ‘close the window’. Some may stretch this to a further screen after 6 months. Be guided by your doctor.
I hope this helps.
Have a good night, everyone 😀