to the editor: The authors of this article state that human immunodeficiency virus (HIV) transmission following a needlestick from a discarded needle in the community setting (as opposed to the health care setting) has not been reported. They also state that “some experts may recommend PEP [postexposure prophylaxis] if the needlestick occurred in a high-risk community setting, such as a park known to be visited by injection drug users.”

At the National HIV/AIDS Clinicians' Consultation Center's Post-Exposure Prophylaxis Hotline (PEPline; http://www.nccc.ucsf.edu), we receive 2,000 calls annually on managing percutaneous exposures. The PEPline does not recommend PEP for exposures to discarded needles in the community.

The common concern with discarded needles is that the needle may have been used by a person with HIV infection. The risk of transmission from discarded needles is unknown, but is considerably lower than the one in 300 chance with percutaneous injuries from a known HIV-positive source in a health care facility.¹ At room temperature, HIV concentration in dried blood is reduced by 90 to 99 percent.² The risk of HIV infectivity declines exponentially outside the body, with the risk of HIV transmission from exposure to dry blood contaminated by research laboratory levels of concentrated virus declining by 90 percent every nine hours.³ The small statistical risk of transmission, further reduced by the rapid decay of transmissible HIV from drying over time, explains why discarded needles in the community setting have not transmitted HIV.

There have been rare and extraordinary circumstances when the PEPline has varied from our general approach of not recommending PEP after exposure to a discarded needle, such as during a police raid in which a needlestick is sustained from a freshly bloody discarded needle used by an intravenous drug user. In such cases, risk of toxicity to the exposed person should be weighed against the potential benefits from PEP.

The risk of toxicity from antiretroviral drugs used for PEP, although small, generally far outweighs potential benefits from PEP following percutaneous injury from discarded needles. Children are often the ones exposed to discarded needles in the community setting; they would be at risk of regrettable toxicities from unnecessary PEP. Therefore, we recommend counseling parents that HIV transmission in these cirucmstances has not been reported and that the risk of PEP toxicity to their child far outweighs potential benefits.

For the treating physician, the recommendation against PEP is almost always the best course of action for exposures from a discarded needle in the community. In all cases, the decision about whether to receive PEP is a personal one. The exposed person needs to be informed of the risks and benefits, and should participate in the decision. The PEPline is available for consultation at 888-448-4911.