Too many people are still contracting HIV and dying of AIDS-related illnesses due to stigma and a lack of access to information and testing, Elton John said on Monday.
Modern medicine means those with HIV can live long, fulfilling lives without infecting others, the singer said in a letter published by Britain's Independent newspaper.
"Everyone should understand the risks of HIV, and everyone who needs it should have the chance of dignified help and support," John wrote in the letter, co-signed by The Independent's owner Evgeny Lebedev.
"That can only happen if we know our status."
About a quarter of the 37 million HIV-positive people worldwide do not know they have the virus. Last year 1.8 million people were infected with HIV.
HIV/AIDS "started off as a disease of young gay men in the 1980s, affluent people in New York, LA and San Francisco," John said while visiting Atlanta, Georgia, last week, according to The Independent.
"Now it's a disease of the poor all across America, but especially in the South. People are being forgotten. That is a disgrace."
African Americans accounted for 44 percent of HIV diagnoses in the United States in 2016, despite making up just 12 percent of the population, according to government data.
Almost six in 10 of the 17,528 black Americans diagnosed with the virus that year were gay or bisexual men.
John's letter coincided with a Christmas appeal to fund projects run by his charity, the Elton John Foundation, in Atlanta, Delhi, Kiev, London, Maputo and Nairobi.
Around 22 million people accessed antiretroviral drugs around the world in 2017, compared with 8 million in 2010. The wider availability of the life-saving medicine has more than halved AIDS-related deaths globally since 2004.
The Elton John Foundation was the seventh-largest funder of HIV/AIDS programs in the world in 2016, according to its impact report published that year.