The first case of AIDS was identified in New York in 1979. The cause of the disease, a retro virus now called Human Immunodeficiency Virus, was identified in 1983-84 by scientists working at the National Cancer Institute in the United States and the Pasteur Institute in France. These workers also developed tests for AIDS, enabling researchers to follow the transmission of the virus and to study the origin and mechanism of the disease. Close relatives of the AIDS virus infect some African monkeys. This fact and the high incidence of infection of people in central Africa has led to the opinion that the AIDS virus originated there. In 1990, the World Health Organization announced that 203,599 cases of AIDS were reported worldwide by the end of 1989, and estimated the actual number of cases to be 600,000.
AIDS is part of everyday life for today’s young people, and they have many questions about this important and often confusing subject. AIDS stands for a condition called Acquired Immuno-Deficiency Syndrome. This is a very long name, but it is easy to understand if you take the different parts one at a time. The word acquired tells us that AIDS is something that a person gets, or acquires, from another person. Although AIDS can be passed from an infected woman to her unborn child, it is not something that you can inherit from your parents like your height or the color of your eyes and hair. It is also not an illness that can occur with no apparent outward cause, as cancer is, or that is a result of the body’s aging process, like Alzheimer’s disease.
Immunodeficiency is another long word, but it, too, is easy if you take it apart. Immuno refers to the body’s immune system. The immune system is the part of the body that fights off infections. When your body is invaded by organism that cause diseases like measles, the flu, or colds, the immune system prevents you from getting sick by attacking and destroying these organism. A deficiency means that there is a lack of something, or not enough of it to work correctly. So immuno- deficiency means that a person’s immune system is not strong enough to work correctly and is lacking the ability to fight off disease-causing organisms that, normally, it would destroy easily.
The last word, syndrome, means a group of conditions or symptoms that show, or indicate, that something is wrong. If you put these three words together, you get a good definition of AIDS. A person with AIDS has a group of conditions or symptoms that indicate that she or he has become infected with a virus that is causing the immune system to become weakened to the point where substances that would normally be destroyed are now able to survive and cause infections and diseases.
the flu virus causes the flu and the measles virus causes measles. In this case, the virus HIV causes AIDS.
We already know that immunodeficiency means that a person has a weakened immune system. If we link this to the word virus, we know that HIV is a virus that causes immunodeficiency, a breakdown in the body’s immune system.
immunodeficiency in humans.
When a person has been infected by the AIDS virus, we say that he or she is HIV-POSITIVE, or seropositive. This means that the person’s blood has tested positive for the presence of HIV. Since their discovery, both HIV and AIDS have been called different things at different times. Since AIDS is caused by HIV, many people simply it HIV disease. Throughout this book, the virus that causes AIDS will be referred to as either HIV or the AIDS virus.
As HIV destroys more and more cells in the immune system, it is easier for opportunistic infections and cancers to invade the body. People with AIDS may get many opportunistic infections during the course of their illness, either one at a time or several at once. Eventually, the immune system is so suppressed that one or more of these infections or cancers develops and cannot be treated success- fully. When we say that someone has died of AIDS, we mean that he or she has died as a result of one of these opportunistic infections or cancers.
Normally, when a virus invades the body, the immune system recognizes the virus and produces antibodies, special proteins that are designed to attack and destroy foreign substances. For instance, when your body is attacked by a flu virus, your immune system recognizes the presence of the flu virus and generates antibodies that are equipped to destroy flu viruses. The immune system also mobilizes special cells called killer lymphocytes, which can attack both the invading virus and cells invaded by the virus. The T-cells we discussed earlier help antibody-forming cells to recognize foreign invaders. They also release certain substances that attract other immune cells to the site of infection.
When HIV destroys the T-cells, it is actually destroying the generals that run the battle between the immune system and the invading substances. Without their leaders, the other cells of the immune system become confused. They don’t know which cells to at tack, and the defenses fall.
To make things worse, the AIDS virus may enter a cell and become dormant, waiting inside the cell to be used at a later time. It can stay there as long as six months without the body recognizing its presence. HIV is also able to mutate, or change its form, very easily. This takes it very difficult for the immune system to design an effective plan of attack. The immune system forms defenses based on the invading substance’s structure. When that structure changes, whatever defenses have been designed become useless. When HIV mutates, the lymphocytes that have been programmed to attack and kill it no longer recognize it, and the AIDS virus can move freely throughout the body until new defenses are created.
Through sexual intercourse, by using infected needles and syringes
Some people develop an acute flulike syndrome, similar to mononucleosis, within two to three weeks of becoming infected with HIV. This is then followed by a long period during which the person is asymptomatic, or has no symptom at all. This period can last for many years. This is dangerous because during this time an infected person may unknowingly pass the virus on to other people. During this asymptomatic period, the virus will continue to multiply. Finally, maybe as long as eight to ten years after the initial infection, the person will once again develop symptoms of HIV infection.
Being HIV-positive simply means that the body has been invaded by the AIDS virus. Just because a person is HIV-positive does not mean that he or she is sick. A person can be HIV-positive for many years before developing any serious infections. A person is said to have full-blown AIDS when he or she meets certain requirements established by the Centers for Disease Control. In general, a person has to test positive for antibodies to the AIDS virus and have been severely affected by one or more of various opportunistic infections or cancers recognized by the CDC as resulting from immunosuppression. The opportunistic infections and cancers used by the CDC to diagnose full-blown AIDS are also called indicator diseases, because they show, or indicate, that a person has AIDS.
That depends on the person who is infected and how quickly the virus breaks down his or her immune system. Some people have been infected for over ten years without developing any major infections or complications. Others develop full-blown AIDS within a year or two of becoming infected. In general, it appears that about 30% of HIV-positive people develop an AIDS indicator disease within the first five years after testing positive, and 50% within nine years.
of people infected with HIV will actually develop full-blown AIDS. Until more time has gone by and researchers have had time to monitor the progress of people infected with in recent years, we won’t have any final answers. What is important to remember is that, even if an HIV-positive person never develops AIDS, he or she will always have the AIDS virus in his or her system for as long as he or she lives and will always be able to transmit the virus to other people.