[Question #6705] Blood Transmission

13 months ago
Hello Doctors:

Thank you for providing this on line service!

I obtained a laceration on the inside of my hand, it bleed for about 10 mins or so and then I placed a band aid on the wound. It did not require any stitches. The next day I removed the bandage to air and healing.  I went out to eat and the server introduced himself to the table by shaking everyone’s hand, just as a reflex and without thinking I shaked his hand and then realized my open wound.  I did not see any obvious blood on my hand after the handshake, however I think I saw a wound on his hand and will admit very unlikely the two wounds matched or pressed together in the handshake.  However if they did, I have learned in your library of already asked questions that HIV transmission could not occur because of no obvious blood and open wounds touching just does not transmit...correct?  However any concern with transmission of Hep C? Or does that also require visible blood?  Thank you!
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
13 months ago
Welcome back to the forum and thanks for your continued confidence in our services.

This is the sort of question that was common in the first few years of the HIV/AIDS epidemic. Even before HIV was discovered and identified as the cause, and before blood tests were available, medical experts and public health agencies such as CDC an all local and state health departments advised the public that because no cases had been observed in people who had not had sexaul or needle-sharing contact with other persons were not at risk; and that there was no risk from non-intimate personal contact. Those basic facts remain true and have been scientifically proved and re-proved over and over.

In addition, within a year or two of the first AIDS cases in the US, the biological explanations became for the low risk from other than sexual contact. They have to do with the large amount of virus exposure required for infection to take hold ("just one virus" doesn't do it); exposure to certain kinds of cells to which the virus initially attaches; and the fragility of the virus, which doesn't survive drying or air exposure. But this knowledge really isn't what's important. In the 40 years of the recognized world wide HIV/AIDS epidemic, it remains the case that virtually nobody has been documented to have acquired HIV without the necessary intimate contact. When the occasional patient is diagnosed and denies such exposures, it always turns out they were wrong:  some lie, being embarrassed or otherwise not willing to reveal such behaviors; others were exposed to partners who, unknown to them, were at high risk (think of the spouse of a husband who, unknown to her, also has sex with men or uses drugs by injection).

Similar comments apply to the hepatitis B and C viruses. Transmission requires much more blood contact than would occur in the circumstances you describe.

Bottom line:  you are not and never will be at risk from interpersonal contact other than sex, needle sharing, etc. Don't worry about it.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD
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13 months ago
Thank you, Dr Handsfield!

Again based on the library of previous questions I felt pretty good no hiv risk, however really do appreciate the in depth response around the scientific/biological reasons.  First I had heard that science has shown that requires certain cells, I am supposing that means cells that typically line anus, vagina (sexual organs) are susceptible rather than as in my case the hand? (This question not for more convincing just personal education :)

As for Hep C, given some legitimate sources say to stay away from shared toothbrushes, razors etc I thought much easier to transmit Hep C via blood or two sticky wounds in my case.  But confirming no testing recommended for Hep C given no visible blood? 

Thanks again!
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
13 months ago
The susceptible cells (bearing the protein called CD4) are under the anal mucosa (lining), but that's only 1 cell layer and easily disrupted. The vaginal lining is not sucesptible, because it has more cell layers; the virus usually must ascend into the uterine cervix or even the uterus itself -- these differences probably explaining why receptive anal sex is a lot higher risk than vaginal. Healing cuts are sealed off by blood clot and growing fibrous tissue.

Don't confuse common sense advice, like not sharing razors or toothbrushes, with high risk in event of actual exposure. Even if the risk is say, only 1 chance in many thousand, why not avoid it if avoidances is so simple? The actual risks from shared razors or toothbrushes is miniscule.
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13 months ago
Thanks Dr Handsfield again for your quick replies and thorough explanations.  I do use this resource from time to time and 9 times out of 10 have my concern or question answered by all the previous answers/questions from you and Dr. Hook.  It is a valuable resource on the unique everyday situations and encounters that come up.  I will add that two sticky wounds touching are not a concern for transmission to the catalog.


H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
13 months ago
Thanks for the thanks. I'm glad to have helped.

That completes the two follow-up exchanges included with each question and so ends this thread. Best wishes and stay safe.
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