Testing and Diagnosis
Of the estimated 1.1 million Americans currently living with HIV, 21 percent do
not know they are infected. People who have been infected recently with HIV
often have few to no symptoms yet are extremely infectious and may unknowingly transmit
the virus to others. Therefore, the Centers for Disease Control and Prevention (CDC)
recommends HIV testing for adults, adolescents, and pregnant women during routine
Regular HIV screenings allow healthcare providers to identify
people who are not aware that they are infected with HIV, so that they can be counseled
on the need to avoid high-risk behaviors, instructed on safe-sex practices, and
given information about starting antiretroviral therapy. HIV testing can also be
performed anonymously if a person is concerned about confidentiality.
When should I get tested for HIV?
You should be tested at least once to find out your HIV status. Ask your doctor
or nurse if and when you need the test again. All pregnant women
should be tested for HIV. All other women should be tested at least once to find
out your HIV status. You should be tested more often if you are at higher risk of
HIV infection. You are at higher risk if you:
- Having unprotected sex with more than one partner
- Injecting drugs, either now or in the past
- Having sex with someone to get money or drugs in return, or having sex with someone
who has traded sex for money or drugs
- Having sex, now or in the past, with someone who has HIV, is bisexual, or injects
- Having another sexually transmitted infection
- If you had a blood transfusion between 1978 and 1985
Remember, these are not the only ways to get HIV, and are not the only reasons to
get tested. All people should know their HIV status. But many do not. About one
in five people infected with HIV or AIDS in the United States do not know they have
it. Many new HIV infections are caused by people unaware that they are infected.
It can take between two weeks and three months after infection for HIV antibodies
to be found in your blood. So, it may take up to three months for an HIV test to
be positive if you were very recently infected.
It is important to know your HIV status for these reasons:
- Many new HIV infections are caused by people unaware that they are infected.
- HIV medicines are more effective if you start them early.
- Starting treatment
early can mean the best health for you and a longer time before you develop AIDS
or other infections. Unfortunately, most people do not find out they have HIV until
the disease is at advanced stages. This limits the treatment options.
There is good news. Though many Americans still don't know they have HIV, more people
are getting tested than ever before. If you don't know your status, it's time to
find out. Testing is quick and easy, and there are many places to get tested: HIV
testing centers, health departments, hospitals, private doctors' offices, and clinics.
To get tested:
If you test negative, you can take steps to stay that way. If you
find out that you are infected with HIV, treatment can slow down the progress of
the virus. If you are pregnant, you also will be able to help
prevent passing HIV to your baby. You can tell your sex partners if you
have HIV and protect them from getting the virus.
Types of HIV tests
Antibody tests are often used to screen for HIV. Antibodies are
things that the body makes to try to fight infections, such as HIV. Antibody tests
look for antibodies to HIV, rather than the HIV itself. Antibodies to HIV often
can be found between two weeks and three months after infection. Depending on the
test and the place where you are tested, results come back within a few minutes
to a few weeks. Ask your doctor or testing center how long you must wait.
These are some kinds of antibody tests:
- Enzyme immunoassay (EIA) tests. These tests are the most common
and give results in a day to one to two weeks.
- Rapid tests. These are antibody tests that give you results quickly,
usually in about 20 minutes. Rapid tests use blood from a vein or a finger stick
or fluid from your mouth to look for antibodies to HIV. If you are HIV-negative,
these are just as accurate as the EIA test. If you test HIV-positive with this test,
you will need a follow-up blood test to confirm the results.
- Home Access Test. With this antibody test, you take your blood
sample at home and mail it to a lab for testing. Results are provided over the phone
by a counselor. You do not have to give your name. You will receive an ID number
to use when you call for the results. There is only one home test approved by the
U.S. Food and Drug Administration (FDA):
Home Access HIV-1 Test System . It takes about seven days to get test results.
Home Access also makes an express test with results available the day the lab receives
your shipment. It takes three to seven days to get test results. You can buy this
FDA-approved test online or at the drugstore. Beware: Online you can buy several
HIV home test kits that are not approved by the FDA. Many of these tests give wrong
If you test positive with an antibody screening test, you will need a second type
of test to confirm that you are infected. You must wait a few days to a few weeks
for the results.
DNA and RNA tests look for parts of the HIV itself. These tests
are not used as often as the antibody tests. But they are useful in some specific
cases, such as testing for HIV in a newborn baby whose mother is HIV-positive and
testing someone who has just become infected (who has acute
HIV Testing in Infants
CDC recommends that all pregnant women get tested for HIV before and/or during delivery.
Knowing the HIV status of the mother allows physicians to prevent mother-to-child
HIV transmission by providing antiretroviral treatment to both mothers infected
with HIV and their newborn infants. However, it is difficult to determine if a baby
born to a mother infected with HIV is actually infected because babies carry their
mothers’ HIV antibodies for several months. Today, healthcare providers can conduct
an HIV test for infants between ages 3 months and 15 months. Researchers are now
evaluating several blood tests to determine which ones are suitable for testing
babies younger than 3 months.
With the right treatments, HIV-positive people can live for decades before developing
AIDS. How can you tell when HIV has progressed to AIDS? You can't. AIDS is not a
diagnosis you can make yourself. Only your doctor can do that. You have developed
AIDS if you are infected with HIV and:
- Your CD4+ count drops below 200 cells per cubic millimeter. (Healthy adults have
CD4 counts of 1,000 or more.)
- You have an AIDS-defining condition, which is an illness that is very unusual in
someone not infected with HIV. You can read about some of these conditions in the
opportunistic infections (OIs).
There are some things that may make it more likely that you will progress to AIDS
sooner. For instance, people who have symptoms when they are first infected with
HIV tend to get AIDS sooner than people who have no symptoms. There are different
kinds (strains) of HIV, and each one of those may progress at a different rate.
Infection with more than one strain of HIV can also lead to AIDS or other infections
AIDS isn't the only reason that you need to keep up-to-date with visits to your
HIV doctor. Today, about half of the people who die from HIV-related infections
are getting infections other than AIDS. You need to keep track of your CD4 count
and ward off OIs to stay healthy. The Centers for Disease Control and Prevention
recommends that HIV-positive women who don't have any symptoms have screenings every
year. Some women may need screenings more often, so ask your doctor what is right
See where to Get an HIV test.
Recommendations for HIV Testing of Adults, Adolescents, and Pregnant Women in Health-Care
Settings,CDC September 2006.
Information published courtesy of NIAID & Womens Health.
This article was last modified in: 06/18/2012