The human immunodeficiency virus (HIV) is one of the most intriguing and challenging viruses to have existed. Evidence suggests that HIV first originated in Africa around 1920 to 1930 as a result of cross-species infections of humans by simian (ape and monkey) viruses. The United States became aware of the disease that HIV causes, acquired immunodeficiency syndrome (AIDS), in 1981, and the virus was identified 2 years later. HIV infects helper CD4 T cells of the immune system, causing their gradual decline in numbers. Scientifically, HIV is an enigmatic challenge that is being deciphered, molecule by molecule, in the search for a vaccine or cure. Sociologically, HIV began as a disease that caused fear and stigma but is now no longer a death sentence, manageable for years with antiviral medications. Worldwide, over 37 million people are living with HIV.
Essential Human Virology (Second Edition), 2023, Pages 209-230,