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AIDS
The term AIDS applies to the most advanced stages of
HIV infection. Official criteria for the definition of AIDS are developed by the
CDC in Atlanta, Ga., which is responsible for tracking the spread of AIDS in the
United States.
In
1993, CDC revised its definition of AIDS to include all HIV-infected people who
have fewer than 200 CD4+ T cells. (Healthy adults usually have CD4+ T-cell
counts of 1,000 or more.) In addition, the definition includes 26 clinical
conditions that affect people with advanced HIV disease. Most AIDS-defining
conditions are opportunistic infections, which rarely cause harm in healthy
individuals. In people with AIDS, however, these infections are often severe and
sometimes fatal because the immune system is so ravaged by HIV that the body
cannot fight off certain bacteria, viruses and other microbes.
Opportunistic
infections common in people with AIDS cause such symptoms as coughing, shortness
of breath, seizures, mental symptoms such as confusion and forgetfulness, severe
and persistent diarrhea, fever, vision loss, severe headaches, weight loss,
extreme fatigue, nausea, vomiting, lack of coordination, coma, abdominal cramps,
or difficult or painful swallowing.
Although
children with AIDS are susceptible to the same opportunistic infections as
adults with the disease, they also experience severe forms of the bacterial
infections to which children are especially prone, such as conjunctivitis (pink
eye), ear infections and tonsillitis.
People
with AIDS are particularly prone to developing various cancers, especially those
caused by viruses such as Kaposi's sarcoma and cervical cancer, or cancers of
the immune system known as lymphomas. These cancers are usually more aggressive
and difficult to treat in people with AIDS. Hallmarks of Kaposi's sarcoma in
light-skinned people are round brown, reddish or purple spots that develop in
the skin or in the mouth. In dark-skinned people, the spots are more pigmented.
During
the course of HIV infection, most people experience a gradual decline in the
number of CD4+ T cells, although some individuals may have abrupt and dramatic
drops in their CD4+ T-cell counts. A person with CD4+ T cells above 200 may
experience some of the early symptoms of HIV disease. Others may have no
symptoms even though their CD4+ T-cell count is below 200.
Many
people are so debilitated by the symptoms of AIDS that they are unable to hold
steady employment or do household chores. Other people with AIDS may experience
phases of intense life-threatening illness followed by phases of normal
functioning.
A
small number of people (less than 50) initially infected with HIV 10 or more
years ago have not developed symptoms of AIDS. Scientists are trying to
determine what factors may account for their lack of progression to AIDS, such
as particular characteristics of their immune systems, or whether they were
infected with a less aggressive strain of the virus or if their genetic make-up
may protect them from the effects of HIV. Scientists hope that understanding the
body’s natural method of control may lead to ideas for protective HIV vaccines
and use of vaccines to prevent disease progression.
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Sex
