UN representatives have said that Russia and the ex-Soviet bloc need to step up their HIV prevention programmes to stop its rapid spread, but stigma and domestic drug policies are hindering progress.
As the world prepares to mark the 30-year anniversary of the first recorded case of HIV, the virus that causes AIDS, effective prevention is "to a large extent missing in the region," UNAIDS regional director Denis Broun told reporters.
Ninety percent of new infections in the region occur in Russia and Ukraine, with a growing share of women infected by sex partners who have contracted the disease through drug injection, according to the United Nations.
Data also show the epidemic spreading through Eastern Europe and Central Asia nearly five times faster than the global average, growing to 1.4 million people in 2010.
But Broun said the disease remains poorly understood among the former Soviet republics.
"When we are talking about prevention among drug users or men who have sex with men, we are talking about people who are not easy to reach ... who are often stigmatised," Broun said.
"To reach them with effective prevention there is a need to work with them ... so their behaviours are better understood. This is what to a large extent is missing in the region."
Only 20 percent of those who need AIDS treatment in the region receive it, making the rest a greater risk and shortening their life expectancy, Broun said.
Meanwhile, a lack of substitution therapy options for heroin users means they "risk being infected and infecting others," he added.
Russia has effectively banned therapy that substitutes heroin with drugs such as methadone that are not injected, something that Broun said has worked well in western Europe. In Russia, methadone is illegal for medical use.
"In western Europe, less than five percent of HIV transmission is through drug use, while here it is over 70 percent," Broun said.
Russia's Health Minister Tatiana Golikova said earlier this year there was no proof that methadone treatment was effective, and drug enforcement officials have said it was more addictive than heroin.
Harm reduction programmes such as needle exchanges are also hanging by a thread in Russia, whose anti-drug policies tend to focus on total abstinence.
They are not officially banned but "there is a lack of enthusiasm to put it mildly, even veiled resistance" to these programmes, said the head of Russia's UN Office on Drugs and Crime, Vladimir Ibragimov.
"With the current trend they will most likely be closed," he said.
Prevention is also hindered by a stigma attached to homosexuality in Russia, Broun said.
"When there is a stigma, men who have sex with men don't have access to prevention and treatment," he said. "They are afraid of going to help centres, and their risk is much higher."
A UN report released last year said HIV among homosexuals in the region is a "hidden epidemic" because of a lack of data and poor attention of national governments to this risk group.
In Russia, gay rights activists have for six successive years failed in their attempts to get a Gay Pride parade sanctioned in Moscow
Last weekend, their latest unsanctioned attempt to hold a meeting near the Kremlin was broken up violently after activists were attacked by ultra-Orthodox and nationalist group members.