As mentioned earlier, HIV/ AIDS is a relatively new health problem. In 1981, several medical practitioners in USA were puzzled because a large number of young men were developing pneumonia due to a new type of bacteria or a rare type of skin cancer called Kaposi's sarcoma. Both these diseases were earlier observed only in people with damaged natural defence mechanism (immune system) of the body. In addition, these patients had several other infections also. Pneumonia is the term used for inflammation of the lungs due to any disease-causing agent. The most common cause of pneumonia is the bacteria called pneumococcus.
Initially, symptoms of pneumonia and kaposi's sarcoma were observed only in homosexual men, but soon they were found in other sections of the society such as those with haemophilia or those who were intravenous drug users. Haemophilia is a hereditary disease where the blood lacks some essential components necessary for clotting of blood and healing of wounds. Intravenous means injecting a substance into the veins. Thus, the medical practitioners concluded that the disease spread through sexual route among the homosexuals and blood route among the intravenous drug abusers or those requiring regular transfusion of blood or blood products.
By 1982, it was evident that a new disease had emerged. During this time, doctors in Africa also came across people with unusual symptoms. It soon became evident that the new disease in the USA and Africa were one and the same. The virus that caused the disease was first identified and isolated independently in 1984 by scientists in France and the US. This new virus was called HIV in 1986. Subsequently, one more virus was identified which was also capable of producing signs and symptoms of AIDS. The virus, first isolated was called HIV-1 and the virus identified later was called HIV-2.
The origin of HIV viruses and AIDS is still a mystery. There have been three main theories about its origin but none of them have been proven so far. In fact all of them have limitations. The first theory is that the HIV existed in a small isolated community and was somehow transmitted to the outside world. The second theory may have been transmitted from an animal, such as monkey. The third theory is that some existing viruses may have changed their genetic structure and therefore developed a new variety of the virus. It is important to remember that all the three theories have several deficiencies and therefore the origin of HIV remains unknown. Also, understanding the origin of the virus may not contribute significantly in developing strategies to prevent and control HIV infection.