Pneumocystis pneumonia (PCP) is a serious infection that causes inflammation and fluid buildup in the lungs. It is caused by a fungus called Pneumocystis jiroveci. Likely spread through the air, this fungus is very common. Most people are exposed to it by age 3 or 4. A healthy immune system can easily control it. But it causes a type of pneumonia in people with weakened immune systems, such as those with HIV (human immunodeficiency virus). This is why it's called an opportunistic infection. Rarely,...
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.