The human immunodeficiency virus (HIV) targets the body’s immune cells, weakening the body’s ability to fight off infections. Understanding HIV’s survival outside the human body, especially on needles, is important for assessing potential risks.
HIV Survival Outside the Body
HIV is a fragile virus that cannot reproduce outside a living human host. It requires specific conditions, such as those found within the body’s cells and fluids, to remain viable and infectious. The virus quickly becomes inactive once it dries out or is exposed to air and sunlight. Studies show that HIV cultivated in laboratory settings, when placed on a surface, loses most of its infectivity, typically 90% to 99%, within several hours.
Factors Influencing Survival on Needles
While HIV is fragile outside the body, its survival on needles, particularly within a syringe, can be extended under specific conditions. The presence of a larger volume of blood offers a protective environment for the virus, shielding it from immediate degradation by air and drying. Temperature also plays a significant role in viral persistence; lower temperatures can prolong HIV survival. Some studies have demonstrated HIV survival for up to 42 days in syringes, especially when refrigerated, and up to 7 days at room temperature, though these are under specific controlled conditions. Conversely, factors like ultraviolet light, drying, and extreme pH levels can quickly inactivate the virus.
Understanding Transmission Risk from Needles
Even though HIV can survive for a period within a used needle, the actual risk of transmission from discarded needles in community settings is extremely low. There are no documented cases of HIV infection occurring from contact with a needle or syringe discarded in a public place. This low risk is due to several factors, including the rapid degradation of the virus once exposed to environmental elements. For transmission to occur, the virus needs to directly enter the bloodstream through a significant opening in the skin or a mucous membrane. While occupational needlestick injuries in healthcare settings, involving fresh blood from a known HIV-positive source, carry an estimated transmission risk of about 0.23% to 0.5%, this scenario differs significantly from encountering a discarded needle.
What to Do After Needle Exposure
If accidental exposure to a discarded needle occurs, immediate action is important. The first step involves thoroughly washing the affected area with soap and running water. It is important to encourage bleeding from the wound but avoid sucking on it.
Following initial wound care, seeking urgent medical attention is crucial. Healthcare providers can assess the risk and determine if Post-Exposure Prophylaxis (PEP) is necessary. PEP involves taking a course of antiretroviral drugs, typically for 28 days, which can significantly reduce the chance of HIV infection if started within 72 hours of exposure, ideally within one to two hours.