The human immunodeficiency virus (HIV) is the virus that causes AIDS (acquired immune deficiency syndrome). HIV is transmitted in blood, semen, vaginal fluids and breast milk.
According to the U.S. Centers for Disease Control and Prevention, HIV is mainly spread by sexual contact, sharing needles and syringes with someone who has HIV, or by being exposed to HIV as a foetus or through breastfeeding.
The kind of needle that is most likely to transmit HIV is a syringe. Different kinds of syringes can hold different amounts of blood, and therefore can keep HIV alive for different lengths of time.
Robert Heimer, an expert on HIV viability inside syringes, reports to the University of California San Francisco's HIV InSite website that HIV can live up to 36 days within a needle.
The best way to prevent getting HIV from a needle is to use a new syringe or other type of needle any time you receive an injection. If you accidentally come into contact with a non-sterilised needle, see a health care provider immediately.
If you cannot avoid using a syringe used by someone else, you should clean the syringe with bleach for "at least two minutes to neutralise both HIV and hepatitis," according to HIV InSite. The syringe should be rinsed again with clean water before use.