AIDS (Acquired Immunodeficiency Syndrome) is the long-term result of infection with HIV (Human Immunodeficiency Virus). "Immunodeficiency" describes a weakness in the body's ability to defend itself against the pathogens (disease-causing agents) which cause illness. Advanced immune deficiency can lead to a number of serious illnesses, and later even death. An HIV infection cannot be cured. Once a person has been infected, regular medical check-ups are important so that they do not miss the best time to start treatment. HIV is treated with antiretroviral drugs. These must be taken every day without fail, and most likely for life.