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What is
AIDS?
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AIDS stands for
Acquired Immunodeficiency (or Immune Deficiency) Syndrome. It
results from infection with a virus called HIV, which stands for
Human immunodeficiency virus. This virus infects key cells in
the human body called CD4- positive (CD4+) T cells. These cells
are part of the body’s immune system, which fights infections
and various cancers.
When HIV invades the body’s CD4+ T cells, the damaged immune
system loses its ability to defend against diseases caused by
bacteria, viruses, and other microscopic organisms. A
substantial decline in CD4+ T cells also leaves the body
vulnerable to certain cancers.
There is no cure for AIDS, but medical treatments can slow down
the rate at which HIV weakens the immune system. As with other
disease, early detection offers more options for treatment and
preventing complications.
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What is the
difference between HIV and AIDS? |
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The term AIDS refers
to an advanced stage of HIV infection, when the immune system
has sustained substantial damage. Not everyone who has HIV
infection develops AIDS.
When HIV progresses to AIDS, however, it has proved to be a
universally fatal illness. Few people survive five years from
the time they are diagnosed with AIDS, although this is
increasing with improvements in treatment techniques.
Experts estimate that about half the people with HIV will
develop AIDS within 10 years after becoming infected. This time
varies greatly from person to person, however, and can depend on
many factors, including a person’s health status and
health-related behaviors.
People are said to have AIDS when they have certain signs or
symptoms specified in guidelines formulated by the US Centers
for Disease Control and Prevention (CDC).
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The CDC’s
definition of AIDS includes: |
- All HIV-infected
people with fewer than 200 CD4+ T cells per cubic millimeter of
blood (compared with CD4+ T cell counts of about 1,000 for
healthy people)
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- People with HIV
infection who have at least one or more than two dozen
AIDS-associated conditions that are the result of HIV’s attack
on the immune system
AIDS-associated conditions include:
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- Opportunistic
infections by bacteria, fungi, and viruses. Opportunistic
infections are infections that are rarely seen in healthy people
but occur when a person’s immune system is weakened.
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- The development
of certain cancers (including cervical cancer and lymphomas).
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- Certain
autoimmune disorders.
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Most AIDS-associated
conditions are rarely serious in healthy individuals. In people with
AIDS, however, these infections are often severe and sometimes fatal
because the immune system is so damaged by HIV that the body cannot
fight them off. |
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History of AIDS |
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The symptoms of AIDS
were first recognized in the early 1980s: |
- In 1981, a rare
lung infection called pneumosystis carinii pneumonia began to
appear in homosexual men living in Los Angeles and New York.
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- At the same
time, cases of a rare tumor called kaposi’s sarcoma were also
reported in young homosexual men. These tumors had been
previously known to affect elderly men, particularly in parts of
Africa. New appearances of the tumors were more aggressive in
the young men and appeared on parts of the body other than the
skin.
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- Other infections
associated with weakened immune defenses were also reported in
the early 1980s.
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Groups most
frequently reporting these infections in the early 1980s were
homosexuals, intravenous drug users, and people with hemophilia,
a blood disorder that requires frequent transfusions. Blood and
sexual transmission were therefore suspected as the sources for
the spread of the infections.
In 1984, the responsible virus was identified and given a name.
In 1986, it was renamed the human immunodeficiency virus (HIV).
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Things that people need
to know |
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Because many of the
first cases of AIDS occurred in homosexual men and intravenous drug
users, some people mistakenly believe that other groups of people
are not at risk for HIV infection. However, anyone is capable of
becoming HIV-infected, regardless of gender, age, or sexual
orientation. |
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About the immune
system |
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Our bodies use a natural
defense system to protect us from bacteria, fungi, viruses, and
other microscopic invaders. This system includes general,
nonspecific defenses as well as weapon s custom-designed against
specific health threats: |
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Nice to know |
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When HIV encounters a
CD4+ cell, a protein called gp 120 that protrudes from HIV’s surface
recognizes the CD4 protein and binds tightly to it. Another viral
protein, p24, forms a casing that surrounds HIV’s genetic material.
HIV’s genetic material contains the information needed by the virus
to infect cells, produce new copies of virus, or cause disease. For
example, these genes encode enzymes that HIV requires to reproduce
itself. Those enzymes are reverse transcriptasse integrase, and
protease. |
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What are the
symptoms of HIV infection and AIDS? |
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Most people newly
infected with the HIV virus show few, if any, symptoms for a few
years. But during this asymptomatic period, HIV is actively
multiplying, infecting, and killing cells in the immune system,
particularly CD4+ T cells. People are very infectious during this
early phase. |
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As the immune system
weakens, symptoms begin to emerge. |
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Early symptoms
of HIV infection |
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Some people, but not
all, develop symptoms within a month or two of exposure to HIV.
These people may have a flu-like illness with such symptoms as:
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- Fever
- Rash
- Headache
- Loss of appetite
- Swollen glands
(enlarged lymph nodes)
- Achymuscles and
joints
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These early symptoms
usually disappear within a week to a month. Most HIV-infected people
who experience these early symptoms won’t see any more signs of the
infection for at least a few years. |
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How is HIV
infection diagnosed? |
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A blood test is used to
confirm whether a person has been infected with HIV. Anyone who has
engaged in risky behavior-such as sharing drug-injecting equipment
or having unprotected sexual contact with an infected person or with
someone whose HIV status is unknown-should consider being tested. |
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A positive HIV
test result does not mean that a person has AIDS
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Not everyone who has HIV
infection develops AIDS. Experts estimate that about half the people
with HIV will develop AIDS within 10 years after becoming infected.
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How HIV
infection is not spread |
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Research indicates that
HIV is NOT transmitted by casual contact such as: |
- Touching or
hugging.
- Sharing
household items such as utensils, towels, and bedding
- Contact with
sweat or tears
- Sharing
facilities such as swimming pools, saunas, hot tubs, or toilets
with HIV-infected people
- Coughs or
sneezes
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In short, studies
indicate that HIV transmission requires intimate contact with
infected blood or body fluids (vaginal secretions, semen, pre
ejaculation fluid, and breast milk). Activities that don’t involve
the possibility of such contact are regarded as posing no risk of
infection. |
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What treatments
are available for HIV and AIDS? |
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Although there is no
treatment currently available that can cure people of HIV or AIDS, a
number of therapies have been developed to help them stay healthier
and live longer. |
- Some medications
target HIV itself, to reduce the virus’s assault on the immune
system.
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- Other treatments
are used to treat or prevent specific opportunistic infections
that threaten the health of people with HIV-damaged immune
systems.
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Treatments that suppress HIV |
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Drugs that
interfere with the activity of a retrovirus such as HIV are
generally known as antiretroviral. All antiretroviral medications
currently approved to treat HIV infection target two viral enzymes
used by the virus to replicate itself. These enzymes, reverse
transcriptase and protease, are involved in different stages of
viral replication. |
