Many of them share needles, a practice that places users at a high risk of contracting the Human Immunodeficiency Virus (HIV), which causes AIDS. Sasha, 31, is a drug user in the southeastern Kazakh city of Almaty.
"It is not usual to speak up about that now, but [I can say that] I am a drug addict," Sasha said. "Well, as you know, that thing leads to AIDS."
HIV weakens the immune system, making it harder for the body to combat other infectious diseases. That leads to Acquired Immune Deficiency Syndrome, or AIDS.
HIV can enter the body through the lining of sexual organs during intercourse. It also spreads through contact with infected blood, which can happen when drug users share needles. There is no evidence, however, that HIV spreads through casual contact, such as kissing or sharing cooking utensils.
Arman Zhusanbay, spokesman for the city of Almaty's Department of Interior Affairs, said that HIV in Central Asia spreads mainly through needle sharing.
"Basically, AIDS spreads among drug addicts. Because, as we all know, very often drug addicts use the same syringes in groups," Zhusanbay said. "That is how they infect each other with HIV."
UNAIDS, the UN body that works to combat AIDS, estimates the number of people living with HIV/AIDS in Central Asia to be about 32,000. Some 16,500 of them are in Kazakhstan, 11,000 in Uzbekistan, 3,900 in Kyrgyzstan, and fewer than 200 in Tajikistan and Turkmenistan combined.
Aleksandr Kossukhin, UNAIDS national program officer in Almaty, said that the majority of people with HIV in the region are under the age of 30. Kossukhin stressed that the sexual transmission of HIV is also increasing, a sign that the disease has gained a foothold in the wider population.
"HIV is predominant among commercial sex workers. Transmission is gradually shifting to the sexual route," Kossukhin said. "Another phenomenon is the growing proportion of women among newly infected people. For instance in Kazakhstan in 2001, about 19 percent of newly registered HIV cases happened among women. In the year 2004, that percentage rose to 31 percent."
The linkages between intravenous drug use and sex work are vivid. Studies among sex workers in the Kazakh cities of Karaganda, Pavlodar, Shymkent, and Uralsk have found that overall, 14 percent injected drugs and 42 percent said they sold sex for drugs.
Sexual transmission accounts for a growing share of HIV infections in Kazakhstan, where more than 25 percent of newly registered infections in 2004 have been attributed to unprotected sex. This appears to be in line with the low levels of condom use reported in the country. Just 58 percent of people aged 15 to 24 said they used condoms with casual partners.
Labor migration from rural to urban areas, both within countries and the region, increases the risk of spreading HIV to the general population. Kossukhin said that the issue is of particular concern in impoverished Tajikistan.
"In the case of Tajikistan, it is believed that about 1 million [people] are migrating annually to Russia and other countries of the Commonwealth of Independent States to earn money," Kossukhin said. "Migrants [having] contacts with commercial sex workers could be easily infected with HIV. In Tajikistan, syphilis is widely spread in the rural areas because men migrate, come [back] home and infect their wives or other [sex] partners."
A further cause for concern is the simultaneous emergence of tuberculosis (TB) with HIV co-infection. TB-HIV co-infection, when it occurs, undermines treatment and care, increases health care costs, and often kills.
In addition to the suffering that HIV/AIDS causes to the patients, relatives, and friends, the disease has a potentially devastating effect on economic development. A recent World Bank study estimates that the rampant spread of HIV would diminish long-term economic growth rates by roughly 10 percent in Kazakhstan and Kyrgyzstan, and by about 21 percent in Uzbekistan by 2015.
Still, governments can help diminish the spread of AIDS if they encourage prevention and treatment. Presenting the UNAIDS Epidemic Update 2004, the agency's executive director, Peter Piot, told reporters in Brussels last week that "there are more and more countries, particularly in Eastern Africa, Cambodia, Thailand, Brazil, where less people become infected. There is now a strong, high political commitment across the world [to prevent AIDS infection], although I would say not yet in Eastern Europe [and Central Asia]."
The UNAIDS report said that fewer than 5 percent of people in Kazakhstan who need antiretroviral therapy -- which slows the progression of HIV infection into full-blown AIDS -- are getting it. It also said that treatment for drug injectors is not yet supported by substitution therapy.
At the same time, stigma and misinformation about the epidemic persist. According to a recent World Bank-commissioned poll in Kyrgyzstan, 98 percent of people have heard of HIV/AIDS. However, 50 percent of people aged 15 to 29 think it can be transmitted from kissing and 30 percent think they can get the disease just by being in the same room with an HIV-positive person.
(Merkhat Sharipzhanov, director of RFE/RL's Kazakh Service, contributed to this report.)