On the very same day the world was celebrating the World AIDS Day, the American College of Physicians released a new practice guideline in the Annals of Internal Medicine website. The group, whose 126,000 members are internists, wants doctors to perform HIV screening tests on all patients over the age of 13.

Back in 2006, the Centers for Disease Control and Prevention called for virtually all patients younger than 65 admitted to hospitals or seen in primary care and emergency rooms to be routinely tested for HIV on an opt-out basis. To be more explicit, patients should automatically be tested unless they specifically refuse. But a study released two weeks ago by the Forum for Collaborative HIV Research showed that only about 5 percent of patients with evidence of serious illness are being routinely checked in hospital emergency rooms for HIV, the virus that causes AIDS. The reasons for which patients are not routinely tested for HIV vary. Among them are the perception of many clinicians that it takes too much time and the reluctance of some insurers to pay for the tests.

Now the American College of Physicians encourages “their patients to get tested, regardless of their risk factors,” said Amir Qaseem, a senior medical associate for the college and lead author of the new guideline. According to it, those considered to have a higher-than-average risk of HIV infections should be offered frequent testing. They include those who use drugs intravenously and share needles, those who have unprotected sex with multiple partners, or those who had a blood transfusion from 1978 to 1985.

“The intent of this guideline is to help prevent the unwitting spread of HIV infection. I would tell my patients that it’s important to know your HIV status so that you do not risk infecting anyone else,” Vincenza Snow, an internist at a free clinic in Philadelphia and director of clinical programs and quality of care at the American College of Physicians, said in a statement.

Furthermore, patients should talk to their doctors about their individual risk, the guideline says.

The standard HIV test looks for antibodies in a person’s blood. When HIV enters a person's body, special proteins are produced. These are called antibodies. Antibodies are the body's response to an infection. So if a person has antibodies to HIV in their blood, it means they have been infected with HIV.

Most people develop detectable HIV antibodies within 6 to 12 weeks of infection. In very rare cases, it can take up to 6 months. It is exceedingly unlikely that someone would take longer than 6 months to develop antibodies.

The HIV-infected population in the US rose to 1.1 million in 2006 from an estimated 994,000 in 2003, meaning that since 2003, HIV prevalence has increased by 11 percent, or 112,000 people, according to a study of the CDC released at the beginning of October.

The CDC previously reported that more people are becoming infected each year than previously estimated, with 56,300 new HIV infections in the US in 2006. Previous estimates put the number of new infections at about 40,000 a year.

Testing for HIV is important because once you know that you’re infected you can take further measures to protect others from getting infected and you can benefit from treatment right away. Recent studies have shown that starting treatment with antiretroviral drug right after you learnt about your infection increases your survival chances by 30 percent.