The human immunodeficiency virus or HIV leads to acquired immune deficiency syndrome, or AIDS. HIV works by destroying the body's T cells, which will slowly but surely cause the immune system to deteriorate and prevent it from fighting off viruses and bacteria that cause disease. Once HIV progresses to AIDS, the immune system is so weak that it is unable to fight often fatal diseases and cancers. Understanding the main causes of AIDS can help alter behaviors to prevent HIV transmission, and may lead HIV-infected individuals to seek treatment which can greatly improve and prolong life.
The Original Source
The Centers for Disease Control (CDC) explains that a type of West African chimpanzee is likely the original source of HIV infection in humans. Scientists believe when humans hunted for meat and came into contact with the chimp's infected blood, a chimp version of the immunodeficiency virus transmitted to the humans and then mutated into HIV.
Sex
Both the CDC and the Mayo Clinic list unprotected sex, or the failure to use a condom, as a main cause of HIV transmission and AIDS. While all unprotected sex is risky, anal sex carries a higher risk than vaginal or oral sex. Sex with multiple or anonymous partners and the presence of sexually transmitted diseases can also increase the risk for infection.
Transfusions/Transplants
HIV infection through organ and/or tissue transplants and blood transfusion is rare today, according to the CDC, thanks to efforts made after 1985 to screen blood donors, blood banks and hospitals. That said, the risk of acquiring HIV infection through blood transfusion or organ/tissue transplants still exists.
Needles
The virus can be easily transmitted through needles and syringes contaminated with HIV-laden blood. For this reason, intravenous drug users who share drug paraphernalia are at high risk for HIV transmission. Although less common, transmission is also possible through accidental needle sticks between HIV-positive patients and health-care workers. The Mayo Clinic states that experts put this risk at less than 1 percent.
Pregnancy
Nearly 600,000 babies acquire HIV each year during pregnancy, delivery or breastfeeding, according to the Mayo Clinic. Women who get tested and receive treatment during pregnancy pose a significantly lower risk to their babies.
