AIDS is acquired immuno deficiency syndrome. It is a
fatal disease caused by a rapidly mutate retrovirus
which attacks the immune system and leaves the
patient susceptible to infections, malignancies, and
neurological disorders. It was first recognized as a
disease in 1981. The virus was isolated in 1983 and
was ultimately named the human immunodeficiency
virus (HIV). There are two forms of the HIV virus, HIV-1
and HIV-2. The majority of cases worldwide are caused
by HIV-1.
It is transmitted primarily by exposure to contaminated
body fluids, especially blood and semen. In 1999 an
international team of genetic scientists reported that
HIV-1 can be traced to a closely related strain of virus,
called simian immunodeficiency virus (SIV), that infects
a subspecies of chimpanzee (Pan troglodytes
troglodytes) in Africa. Chimpanzees are hunted for
meat in this region, and it is believed the virus may
have passed from the blood of chimpanzees into
humans through superficial wounds, probably in the
early 1930s.
In a process, HIV infects the CD4 cells of the body's
immune system, cells that are necessary to activate B-
lymphocytes and induce the production of antibodies.
This is still imperfectly understood. The body fights
back producing billions of lymphocytes daily to fight the
billions of copies of the virus. The immune system is
eventually plagued and the body is left vulnerable to
opportunistic infections and malignancy.
Some people develop flu like symptoms shortly after
infection, but many have no symptoms. It may be a few
months or many years before serious symptoms
develop in adults; symptoms usually develop within the
first two years of life in infants infected in the womb or
at birth. Before serious symptoms occur, an infected
person may experience fever, weight loss, diarrhea,
fatigue, skin rashes, shingles thrush, or memory
problems. Infants may fail to develop normally.
The definition of AIDS has been refined, as more
knowledge has become available. In general it refers to
that period in the infection when the CD4 count goes
below 200 from a normal count of 1,000 or when the
characteristic opportunistic infections and cancers
appear. The conditions associated with AIDS include
malignancies such as Kaposi's sarcoma, non-Hodgkin's
lymphoma, primary lymphoma of the brain, and
invasive carcinoma of the cervix.
Opportunistic infections characteristic of or more
virulent in AIDS include Pneumocystis carinii
pneumonia, herpes simplex, cytomegalo virus, and
diarrhea diseases caused by cryptosporidium or
isospora. In addition, hepatitis C is prevalent in
intravenous drug users and hemophiliacs with AIDS,
and an estimated 4 to 5 million people who have
tuberculosis are coinfected with HIV, each disease
hastening the progression of the other.
Children may experience more serious forms of
common childhood ailments such as tonsillitis and
conjunctivitis. These infections conspire to cause a
wide range of symptoms like coughing, diarrhea, fever
and night sweats, and headaches and may lead to
extreme weight loss, blindness, hallucinations, and
dementia before death occurs.
HIV is not transmitted by casual contact. Transmission
requires a direct exchange of body fluids, such as blood
or blood products, breast milk, semen, or vaginal
secretions, most commonly as a result of sexual activity
or the sharing of needles among drug users. Such a
transmission may also occur from mother to baby
during pregnancy or at birth. Saliva, tears, urine, feces,
and sweat do not appear to transmit the virus.
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