Human Immunodeficiency Virus is a particular type of virus that causes AIDS. These viruses affect blood and other body secretions of the infected individual, without revealing any symptom. The infectious nature of the virus causes the disease to spread from one person to another. Such infections happen when the secretions come in contact with the vagina, anal area, mouth, eyes or any cut in skin. Modern treatments are able to prevent HIV infection from becoming AIDS. Medications have serious side effects. The screening tests involve a series of blood tests. The first test is called ELISA. This test looks for antibodies to HIV in the blood. This test may reveal the blood to be HIV-positive even if the cell is not affected at all. Thus, a second test called Western Blot Assay is conducted for confirmation. Recent infection may show a negative result. In these cases, repeat testing is recommended.