You go every year for your regular medical checkup. Your doctor performs a thorough medical history and physical examination. You expect to discuss how to maintain medical fitness and possibly have blood drawn to check your cholesterol.

But you are surprised when you doctor asks you if you want to have an HIV test. Your immediate thought may be: "I'm not at risk for HIV. This happens to other people."

For more than 1 million people in the United States, however, the human immunodeficiency virus (HIV) -- the virus that causes AIDS -- is a grim reality. Of those infected, approximately 25 percent aren't aware that they are HIV positive.

And each year there are approximately 40,000 new HIV infections in the United States, most of which are transmitted by those 25 percent who do not know that they are infected. It is a situation that last year spurred the U.S. Centers for Disease Control and Prevention (CDC) to revise recommendations for HIV testing to better control the HIV epidemic.

An Epidemic on Home Soil

It has been more than 25 years since we first heard about a new disease -- one which was lethal, sexually transmitted, and blood-borne.

Stigma soon arose from the disease called AIDS, as it emerged initially among gay and bisexual men, as well as those who used intravenous recreational drugs. A diagnosis of HIV back then meant near certain death in a relatively short period of time -- and being viewed by others with fear and discrimination.

Fortunately, over the past decade, we have seen the emergence of new and improved therapies which have dramatically extended the lives of people with HIV infection. What was once a uniformly fatal disease can now be managed as a chronic condition in which people can live for many years, even decades.

Symptoms and Progression of HIV Infection

A person infected with HIV may have a mild flu-like illness with sore throat and fatigue for a few weeks after becoming infected. People may attribute these symptoms to the flu or another virus and never go to see a physician.

It may take five to 10 years after infection with HIV virus for them to progress to acquired immunodeficiency syndrome (AIDS). During this time they usually have no symptoms, but they are capable of transmitting this infection to others unknowingly.

But once these individuals develop AIDS, they are faced with a syndrome characterized by a severely weakened immune system and susceptibility to normally harmless germs.

If treated with and maintained on highly active antiretroviral therapy (HAART), many people can keep HIV "in check." There is no known cure for HIV, but HAART delays progression to AIDS and can significantly reverse immune system weakness.

Who Is at Risk for HIV?

HIV can be transmitted by sexual activity, sharing needles with others who may be infected, and from an HIV-infected mother to her baby at birth.

Sexual activity means both heterosexual and homosexual intercourse. Worldwide, heterosexual transmission is the most common way to transmit HIV. Blood used for transfusions early in the epidemic was a source for HIV transmission, but testing of blood and donor screening since 1985 has made the blood supply extremely safe in the United States.

Many people are sexually active but do not see themselves at risk for HIV. They mistakenly believe that they can recognize HIV infection in their sexual partner even though there may be no clinical symptoms. It only takes one encounter to transmit the infection.

New CDC Testing Recommendations

The new recommendations are a step toward making HIV testing a routine part of medical care. In the past, HIV testing was emphasized for those in high-risk groups and required a separate written informed consent and prevention counseling. The following are some important recommendations from the CDC regarding HIV testing:

HIV screening is recommended for all patients as a routine part of medical care unless the patient refuses testing; All pregnant women should be screened for HIV; Persons at high risk should be screened every year for HIV infection; Separate written informed consent for HIV testing should not be required, but all testing should be done voluntarily and with consent.

HIV testing is governed by a wide range of federal and state laws and it will take time and effort to amend many laws which prevent full implementation of the CDC guidelines.

There are conventional HIV tests and a rapid HIV test available. They both measure HIV antibody produced by the body in response to infection. Rapid HIV screening tests can deliver a result in 30 minutes, thereby providing test results during the same visit. Conventional tests will require the patient to return for results after several days.

Whenever an HIV test is positive, it must be confirmed by a second test. During the first two to eight weeks after infection, an HIV test may be falsely negative; it is therefore important for people who may have been exposed to repeat HIV testing in three to six months.

New Recommendations Go a Long Way

There is an obvious benefit to the HIV-infected individual to be recognized early in the disease. Early detection leads to early treatment and a healthier and longer lifespan.

In many studies it has been shown that those who became aware of their HIV infection reduced their high-risk sexual behaviors and decreased transmission to their partners. Thus, more expanded testing and identification of those HIV infected can help prevent future HIV infections.

Dr. José A. Montero is associate professor of medicine at the Division of Infectious Diseases and International Medicine at the University of South Florida College of Medicine in Tampa.