How HIV Is Diagnosed

The only way to diagnose HIV (an informal term often used to refer to infection with the human immunodeficiency virus) is with an HIV test. There are a variety of such tests, some using samples of blood, others saliva or urine. Testing typically takes place at a point-of-care location (a doctor's office, hospital, clinic, or even drugstore, for example). There also are tests that can be done at home (similar to home pregnancy tests). Some HIV tests look for the presence of the virus itself and others rely on the presence of antibodies to the virus created by the immune system.

In most cases, how or where a person is tested for HIV matters less than that he or she has the test at all: For someone who has been infected with HIV, early diagnosis is vital. It can make the difference between living a long and otherwise healthy life thanks to highly effective antiretroviral medications for HIV and succumbing to the serious illness.

A Life-Saving Test

The initial symptoms of HIV so resemble those of more innocuous viral infections that unless they know they've been exposed to the virus (by engaging in risky behavior, for instance), most people aren't likely to suspect HIV infection. Once the early symptoms resolve, the virus goes into a long remission during which it silently destroys cells in the immune system. It's not until this process has gone on long enough (typically eight to 10 years) that signs of compromised immunity begin to occur—the late stage of infection known as AIDS (acquired immunodeficiency disease).

At this point, treatment isn't likely to be effective, which is why public health organizations such as the U.S. Centers for Disease Control and Prevention (CDC) have specific guidelines for HIV testing based on factors such as age, sex, and lifestyle.

The CDC recommends that:

Everyone between 13 and 64 gets tested for HIV at least once as part of routine health care
People with risk factors for exposure to HIV get tested more frequently—at least annually, in most cases
Gay, bisexual, and other men who have sex with men (MSM) be tested at least once a year
Sexually active MSM at increased risk of the infection get tested even more often, such as once every 3 or 6 months

In addition, because an HIV-positive woman can pass the virus to an unborn child, the U.S. Preventive Services Task Force recommends that doctors "screen all pregnant women for HIV, including those who present in labor who are untested and whose HIV status is unknown."

Types of HIV Tests

Again, there are several types of tests for screening for HIV. Most are relatively accurate, although point-of-care tests tend to be more reliable than home tests, since these usually use a sample of blood and are conducted by trained clinicians, decreasing the likelihood of error.

There also are direct and indirect methods of detecting HIV:

Direct testing detects either antigens (proteins on the surface of the virus) or RNA (the virus’ genetic material)
Indirect testing screens for antibodies—proteins produced by the immune system in response to the virus

HIV Test Options
Option	Method	What it tests for	Time until results	Good to know
Rapid point-of-care tests	Finger prick, oral swab of the gums, or with a urine sample	Both HIV antigen and antibodies	About 20 minutes	The most accurate of these uses a blood sample—the combination HIV Ag/Ab test
Standard point-of-care tests	Blood draw for a sample that is then sent to a lab	HIV antibodies	Five to 10 days	Also known as the HIV ELISA: now less common than the combination HIV Ag/Ab test
Rapid at-home tests	Saliva	HIV antibodies	About 20 minutes	More private, less accurate than point-of-care tests
Home collection kits	Drop of blood transferred to a test card and sent to a lab	HIV antibodies	About on business day after receipt by lab	Can be difficult to obtain a blood sample by yourself
Nucleic acid tests (NATs)	Blood sample	HIV RNA (genetic material)	A couple of days	Pricy; can detect HIV earlier than other types of tests; sometimes use to screen donated blood or newborns

With the exception of the NAT, a positive result from an HIV test is regarded as a preliminary positive, which means a second test will be needed to confirm the diagnosis.

A Word From Verywell

Being tested for HIV is nothing less than stressful but its absolutely necessary. If your results are negative, you can move forward with a better understanding of how to stay that way. If you are positive, you can begin HIV therapy that will allow you to live a long, healthy, and productive life.