As a result, many patients are not only ill with AIDS, but are often battling addiction at the same time. Patients quite often have to go through withdrawal when they first arrive in hospital. And keeping patients compliant with their medication can be a challenge since many tend to interrupt treatment, especially when they find themselves using drugs again.

"This is the dark side of our life," explains Dr Vladimir Musatov, Deputy Chief Physician at the Botkin Infectious Diseases Hospital, as he led the way through the dim, grungy corridors of the neglected and dilapidated building that houses patients receiving AIDS treatment.

The hospital, located in the heart of St. Petersburg, is the largest in the world dedicated to infectious diseases. The doctors here work with the most difficult and hard to reach of patients. Many come to them addicted to drugs, co-infected with tuberculosis and unaware that they are living with advanced HIV.

After visiting a hospital near his home for what he thought was a case of the flu, Alexey, a 25-year-old construction worker, was transferred to the AIDS clinic at Botkin Hospital. He had been diagnosed with HIV. His immune system was in such disrepair that at the time of admittance he only had 13 of the body's key infection fighting agents, known as T4 cells. Healthy adults usually carry a T4 cell count of 1,000 or more.

"Initially I was very angry with the doctors here," Alexey reminisces in the gloomy room with a single bed that he's come to call home. "I was banging chairs, shouting at them." Now that he has been on treatment for three months, things are better, he says. His T4 cell count is up to 157 and doctors say that his steady progress means he'll be able to return home to his family in a few weeks.