Friday, 20 March 2009

The Cause of Aids

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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