Globally, there were 37.9 million people living with HIV worldwide at the end of 2018, with approximately 1.7 million becoming newly infected in 2018. Approximately 70% of people living with HIV are in sub-Saharan Africa. New cases peaked in 1999 (3.16 million) and have gradually decreased since then. Approximately 80% of new HIV infections are from people who do not know they are infected or who are not receiving regular care. The transmission rate was zero in patients taking antiretroviral therapy who were virally suppressed.
In the US, there were an estimated 38,281 diagnoses of HIV infection in 2017. The majority of diagnoses among males were in men who have sex with men (MSM). MSM accounted for 67% of all diagnoses in the US in 2017, while heterosexual contact accounted for 24%, and injection drug use accounted for 6%. The number of new infections in the US was highest in the 25-29 year old age group in 2017. Between 2010 and 2016, infection rates remained stable in MSM, decreased by approximately 17% in heterosexual men and women, and decreased by approximately 30% in people who inject drugs. However, infection rates have increased among certain demographics, including Latino MSM and black MSM aged 25-34 years.
In the World Health Organization European Region (consisting of 53 countries, and including data for the Russian Federation), there were 159,420 newly reported cases in 2017 (20 new infections in 100,000 population). Transmission among heterosexuals was the largest single route of infection, accounting for 49.4% of newly diagnosed cases. A total of 21.2% of new infections were attributed to MSM, and 13% to injecting drug use. The number of new infections was highest in the 30-39 year old age group (36%). In the UK, new diagnoses decreased by 6% in 2018 (compared with 2017) to 4484 cases (with 1908 of those in gay and bisexual men). The overall number of people living with HIV in the UK was estimated to be 103,800 in 2018 (an estimated 6700 people were living with undiagnosed HIV infection). The incidence in MSM is falling in some countries.
Survey data underscore the disproportionate impact of the AIDS epidemic on women, especially in sub-Saharan Africa. Globally, 52% of adults living with HIV infection are women. In the US, women accounted for 19% of estimated HIV diagnoses in 2017, with 86% acquired through heterosexual transmission.
Overall, globally, the HIV incidence rate is believed to have peaked in the late 1990s and to have stabilized subsequently, notwithstanding increasing incidence in a number of countries. Changes in incidence along with rising AIDS mortality have caused global HIV prevalence to level off. However, the numbers of people living with HIV have continued to rise, due to population growth and, more recently, the life-prolonging effects of antiretroviral therapy. In sub-Saharan Africa, the region with the largest burden of the AIDS epidemic, data also indicate that the HIV incidence rate has peaked and is starting to plateau in most countries. However, the epidemics in this region are highly diverse and especially severe in southern Africa, where some of the epidemics are still expanding.
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