AIDS is a disease which is caused by HIV - Human Immunodeficiency Syndrome - which has infected over 33 million people worldwide in 2010 and killed approximately 5% of its prey. The figure bellow shows how people living with HIV are spread around the world (source: wikipedia).
Before we start to get into the scientific discussion on this syndrome, we must understand the true meaning of the two terms mentioned above- HIV and AIDS. HIV is the virus which after entering the body will attack mainly the white blood cells of the body which are the human body's soldiers. The virus will feed off and use the energy of the host cell and eventually destroy it. So, the role of the Human Immunodeficiency Virus is to damage the Immune System of the human body - as quiet visibly seen in the name of the virus. To be more precise, the virus attacks the CD4 cells, which are immune cells. The normal concentration of these in a healthy body with a reliable and strong immune system is between 450 and 1200 in a cubic millimetre of blood. But as the virus attacks more and more of the CD4 cells, the immune system will become weaker and weaker and increasingly vulnerable to "opportunistic infections".
AIDS is known as the stage in which the concentration of the CD4 cells has fallen bellow 200 per 1 cubic millimeter of blood. This means that the body's defence system has become extremely weak and is literally an open target for any bacteria or virus that's floating past.
Tuberculosis are also at a higher risk.
The Human Immunodeficiency Virus can be spread in various ways which will be examined later on, but it's only logical to see where the virus originated from first. According to the Centers for Disease Control and Prevention (CDC), the source of HIV has been tracked down to a specie of chimpanzee in Africa. Scientists believe that the chimpanzee's version of the Immunodeficiency Syndrome called the Simian Immunodeficiency Virus (SIV) was passed onto humans when they were hunted and eaten and therefore came into contact with the primate's infected blood. It is believed that the virus spread to the other countries of the world in the following decades.
To understand the symptoms caused by AIDS we must realize that what the HIV does is weakening the immune system and therefore killing the body's soldiers. In this case, bacteria, viruses and fungi can affect the patients body dramatically. The systematic symptoms to infection such as weight loss, fever, sweating and weakness may be observed. Also, the body becomes vulnerable to many cancers such as the immune system cancer called lymphomas and others such as Kaposi's sarcoma.
There is no vaccine nor cure for HIV or AIDS and the best solution is to prevent the virus from entering the body. If a patient is diagnosed with HIV, an antiretroviral treatment can take place. Again this is not a publicly available solution and the hunt for better methods must continue.