A recent research presented at the world AIDS conference has pointed out that less than 10 percent of injecting drug users (IDUs) receive appropriate assistance that will help them from spreading HIV.
Of the roughly 16 million IDUs around the world, some three million have the human immunodeficiency virus (HIV), although the tally could be as high as 6.6 million, it said.
By being marginalised and criminalised, this group can become a major vector for spreading HIV through shared use of syringes or through prostitution to feed a drug habit, it said.
Only eight percent have safer, legal substitutes such as methadone to opiate drugs like heroin.
And only four percent of IDUs with HIV receive antiretroviral drugs, which can repress blood levels of the virus to such low levels that the risk of contaminating others can be slashed by more than 90 percent.
These are the most effective techniques to help drug users to return to good health, wean themselves off their addiction and reduce their risk to others, according to the papers, which were also published by the British journal The Lancet.
Combined, these practices can help reduce HIV prevalence among drug users by more than half, investigators have found.
The studies were presented at the 18th International AIDS Conference in Vienna, which has swung a spotlight on the state of the pandemic of HIV/AIDS in the countries of the former Soviet bloc.
In these states, HIV spread is being driven especially by the overlap between drug use and sex work.
From 2001 to 2008, the number of people in Eastern Europe and Central Asia rose by two-thirds, reaching 1.5 million, according to the UN agency UNAIDS.
More than two-thirds of them live in Russia, which combined with Ukraine accounts for more than 90 percent of the region's infections.
More than 33 million people have HIV, two-thirds of whom live in sub-Saharan Africa, where the pandemic is driven especially by sexual intercourse.
Last year UNAIDS said 19 percent of resources needed for preventing HIV should be earmarked for IDUs, but as little as one percent was allocated this way.