Cytomegalovirus (CMV) is a herpes virus. It is very common, infecting up to 80% of people in the U.S. by age 40. Normally, it hides out in the body. This is not a problem for most people because a healthy immune system can easily control it. However, it can cause severe disease in people with HIV (human immunodeficiency virus). It's able to take advantage of a weakened immune system, which is why it's called an opportunistic infection. The most common illness CMV causes is retinitis, an eye infection...
A woman who is infected with HIV can spread the virus to her baby during pregnancy, delivery, or breast-feeding.
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.4
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%.4 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.