HIV<span> (</span>human immunodeficiency virus<span>) is a virus that attacks the immune system, the body's natural defense system. Without a strong immune system, the body has trouble fighting off disease. Both the virus and the infection it causes are called </span>HIV<span>. White blood cells are an important part of the immune system. and also </span>The virus can be transmitted through contact with infected blood, semen, or vaginal fluids.Within a few weeks of HIV infection, flu-like symptoms such as fever, sore throat, and fatigue can occur. Then the disease is usually asymptomatic until it progresses to AIDS. AIDS symptoms include weight loss, fever or night sweats, fatigue, and recurrent infections.No cure exists for AIDS, but strict adherence to anti-retroviral regimens (ARVs) can dramatically slow the disease's progress as well as prevent secondary infections and complications.