Epidemiology of HIV/AIDS

HIV/AIDS, or Human Immunodeficiency Virus, is considered by some authors a global pandemic. However, the WHO currently uses the term 'global epidemic' to describe HIV. As of 2018, approximately 37.9 million people are infected with HIV globally. There were about 770,000 deaths from AIDS in 2018. The 2015 Global Burden of Disease Study, in a report published in The Lancet, estimated that the global incidence of HIV infection peaked in 1997 at 3.3 million per year. Global incidence fell rapidly from 1997 to 2005, to about 2.6 million per year, but remained stable from 2005 to 2015.

Sub-Saharan Africa is the region most affected. In 2018, an estimated 61% of new HIV infections occurred in this region. Prevalence ratios are "In western and central Europe and North America, low and declining incidence of HIV and mortality among people infected with HIV over the last 17 years has seen the incidence:prevalence ratio fall from 0.06 in 2000 to 0.03 in 2017. Strong and steady reductions in new HIV infections and mortality among people infected with HIV in eastern and southern Africa has pushed the ratio down from 0.11 in 2000 to 0.04 in 2017. Progress has been more gradual in Asia and the Pacific (0.05 in 2017), Latin America (0.06 in 2017), the Caribbean (0.05 in 2017) and western and central Africa (0.06 in 2017). The incidence:prevalence ratios of the Middle East and North Africa (0.08 in 2017) and eastern Europe and central Asia (0.09 in 2017)". South Africa has the largest population of people with HIV of any country in the world, at 7.06 million as of 2017. In Tanzania, HIV/AIDS was reported to have a prevalence of 4.5% among Tanzanian adults aged 15–49 in 2017.

South & South-East Asia (a region with about 2 billion people as of 2010, over 30% of the global population) has an estimated 4 million cases (12% of all people infected with HIV), with about 250,000 deaths in 2010. Approximately 2.5 million of these cases are in India, where however the prevalence is only about 0.3% (somewhat higher than that found in Western and Central Europe or Canada). Prevalence is lowest in East Asia at 0.1%.

In 2017, approximately 1 million people in the United States had HIV; 14% did not realize that they were infected.

In 2017, 93,385 people (64,472 men and 28,877 women) living with diagnosed HIV infection received HIV care in the UK and 428 deaths. 42,739 (nearly 50%) of those are gay or bisexual, a small segment of the overall population.

In Australia, as of 2017, there were about 27,545 cases. In Canada as of 2016, there were about 63,110 cases.

A reconstruction of its genetic history shows that the HIV pandemic almost certainly originated in Kinshasa, the capital of the Democratic Republic of the Congo, around 1920. AIDS was first recognized in 1981, in 1983 the HIV virus was discovered and identified as the cause of AIDS, and by 2009 AIDS caused nearly 30 million deaths.