Let's say that someone uses a needle which has some old blood infected with HIV. In this case, is it possible for them to get infected with HIV?

  • $\begingroup$ Doesn't the oxygen of air eliminate the virus? $\endgroup$
    – Alex
    Commented Jun 22, 2014 at 18:54
  • $\begingroup$ It's important to define how old is "old", here, I think. I rephrased the question a bit so that it focuses more on the science than an individual diagnosis. $\endgroup$
    – jonsca
    Commented Jun 22, 2014 at 19:13
  • $\begingroup$ Thanks. Let's not define old in order to have a complete answer. I suppose the answer is based on that. $\endgroup$
    – Alex
    Commented Jun 22, 2014 at 19:17

1 Answer 1


Yes, you can transmit HIV with infected needles/syringes. This is a quite common mechanism of transmission when drug addicts share and re-use needles and syringes and also in third world hospitals with poor hygiene standards.

A drop of blood is considered infectious at least until it has completely dried up (some research showed that it might be contagious for up to 5 days longer when the conditions are right, see reference 1 below). Mostly HIV is senstive against high temperatures (over 60°C), while it is stable at low temperatures. It is very sensitive against shifts in pH (below 7 or above 8) and also against desinfectants like bleach. Have a look at the references below, a lot of research has been done by Abdala et al. in this field. You can find his whole reference list here (it contains more articles in this field).


  1. Survival of HIV-1 activity after disinfection, temperature and pH changes, or drying.
  2. Survival of HIV-1 in syringes.
  3. Survival of HIV-1 in syringes: effects of temperature during storage.
  4. Viability of HIV-1 in syringes: implications for interventions among injection drug users.

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