MONDAY, Dec. 1 (HealthDay News) -- Physicians should routinely screen all patients 13 years and older for HIV, says a new practice guideline released Monday by the American College of Physicians (ACP). HIV is the virus that causes AIDS.

In the United States, HIV affects more than one million people, and about 20,000 new infections are caused each year by people who don't know they have HIV. Screening can help identify undiagnosed cases of HIV infection and prevent further transmission of the virus.

"The purpose of the guideline is to present the available evidence to physicians as a way to help guide their decisions around screening for HIV in their practice," guideline lead author Dr. Amir Qaseem, senior medical associate in ACP's Clinical Programs and Quality of Care Department, said in a group news release. "ACP recommends that physicians adopt a routine screening policy for HIV and encourage their patients to get tested, regardless of their risk factors."

The new guideline, released on World AIDS Day, says doctors should offer initial screening to all patients and should determine the need for repeat screening intervals on a case-by-case basis. Patients at higher risk for HIV infection should be retested more frequently than patients at average risk.

High-risk patients include: those who've shared injection needles; had a blood transfusion between 1978 and 1985; have had unprotected sex with multiple partners; have a sexually transmitted disease, or have had unprotected sex with anyone in any of these risk categories.

Patients should talk to their doctors about their individual risk, says the guideline, which was published on the Annals of Internal Medicine Web site.

"The intent of this guideline is to help prevent the unwitting spread of HIV infection," Dr. Vincenza Snow, director of clinical programs and quality of care at ACP, said in the news release. "I would tell my patients that it's important to know your HIV status, so that you do not risk infecting anyone else. Besides, an AIDS test is very simple and quick, and can be performed during a routine exam."

• More News on AIDS

Related MedlinePlus Pages:

• AIDS