The most common way people are infected with HIV is by having sex with an infected person. You can't tell by looking at a person whether they have HIV, so you have to protect yourself -- and your sex partner.
and HIV Prevention
Don't have unprotected sex outside marriage or a committed relationship. If you or your partner has ever had unprotected sex -- or if either of you uses injected drugs -- the only way to be sure you don't have HIV is to get tested. Have two...
A woman who is infected
with HIV can spread the virus to her baby during pregnancy, delivery, or
How HIV is not spread
The virus doesn't survive well outside the body. So HIV cannot be spread through casual contact with an infected person, such as
by sharing drinking glasses, by casual kissing, or by coming into contact with the person's sweat or urine.
It is now extremely rare in the United States for HIV to
be transmitted by
blood transfusions or organ transplants.
The window period
After you've been infected, it can take 2 weeks to 6 months for your body to start making HIV antibodies.
This means that during this time you could have a negative HIV test, even though you have been infected and can spread the virus to others.
Most people go through the following
stages after being infected with HIV:
Initial stage (stage 1)
The first stage of HIV infection is defined by the U.S. Centers for Disease Control and Prevention (CDC) as a CD4+ cell count of at least 500 cells per microliter or a percentage of CD4+ cells at least 29% of all
lymphocytes. People in this stage don't have any symptoms.3
Chronic stage (stage 2)
The second stage of HIV infection is defined by the CDC as a CD4+ cell count of 200
to 499 or a percentage of CD4+ cells of 14% to 28%.3 It may take years for HIV symptoms
to develop during this stage. But even though no symptoms are present, the virus is making copies of itself (multiplying) in the body during this time.
HIV multiplies so
quickly that the
immune system can't destroy the virus. After years of
fighting HIV, the immune system starts to weaken.
AIDS (stage 3)
AIDS occurs when the CD4+ cell counts drop below 200, the percentage of CD4+ cells is less than 14%, or an AIDS-defining condition is present.4
If HIV isn't treated, most people get
AIDS within 10 to 12 years after the initial infection.
With treatment for HIV, the progression to AIDS may be delayed or