MadSci Network: Immunology

Re: Is it likely that hiv can enter the bloodsteam from a 6 day old finger cut?

Date: Sat Sep 11 13:09:08 2004
Posted By: Mike Conrad, Post-doc/Fellow, Microbiology, UNC
Area of science: Immunology
ID: 1093294191.Im

Is it likely that hiv can enter the bloodsteam from a 6 day old finger

It is very unlikely that HIV could enter the bloodstream through a 6 day
old finger cut, especially if the cut has healed over with unbroken skin.
The risk is essentially zero.  Being a scientist, it is very difficult to
say exactly zero, but for all practical purposes it's zero.  It's like the
Powerball Lottery.  You could play it all day, and the odds of winning are
practically zero.

Continuing with your question, if the fluid was dry, the odds are even 
closer to zero.  In the lab, dried samples are treated as potentially
infective, and that's good lab technique.  But it is very hard to find
active HIV in a dried sample.  (Viable HIV have been found from high
concentration dried samples kept in a constant humid environment, but this
is a very artificial situation.)
After 5 or 6 days, the newly healed skin will look pink since it is
thinner and has not toughened (remodeled).  But once the wound has healed
over it is covered with skin cells.  These cells lack the major receptor
(CD4) for HIV and are generally not infected by HIV.  (In the test tube,
high concentration HIV can be forced into these cells using alternate
receptors, but again, these are very artificial conditions.)

In any case, the ideas involved with "safer sex" should be followed
to reduce any chance of infection.  This means avoiding exchange of

To alleviate any worries, an HIV test can be done.  About a month after
exposure, the test becomes useful.  You also can talk to someone at one of
these numbers:

I hope this answers your questions.  Mike Conrad.

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