A growing number of people are living with HIV, according to a November 2009 United Nations report that also noted that significant progress has been achieved in reducing the number of AIDS-related deaths. (Tim Wimborne/Reuters)

When AIDS surfaced on the medical radar screens in 1981, the diagnosis was a death sentence.

But — over the past decade or so — that's begun to change as evidence began to mount that people could live many years with AIDS if they were taking certain drugs.

A November 2006 study in the New England Journal of Medicine provided the strongest evidence yet that life-long antiretroviral therapy had turned HIV/AIDS into a chronic disease rather than a countdown to death.

The study showed that people who take a break from HIV therapy to reduce the side-effects are more than twice as likely to die than those who take a steady course of the drugs.

"Quite unexpectedly, our results show that interrupting therapy increases the risk of serious non-AIDS-related events," Dr. Wafaa El-Sadr, one of the trial's co-chairs, said in a statement.

The trial on nearly 5,500 people infected with HIV in 33 countries was stopped early when the advantages of continuing therapy were clear from the preliminary data.

It's a big leap since 1981, when doctors in New York and Los Angeles noticed that increasing numbers of previously healthy young men were seeking help for symptoms that included severe weight loss, virulent herpes infections, life-threatening lung and brain infections and previously rare cancers. Around the same time, doctors in France, Zaire and Haiti also noticed a similar syndrome in both men and women.

The remarkable thing these patients had in common was that they were dying from infections to which most healthy people were immune. The doctors were puzzled because they could find no obvious cause for this new syndrome. If a line can be drawn in time, then 1981 marks the official beginning of the AIDS epidemic.

The mystery illness

By 1983 French researchers had isolated a virus that would later be called HIV (human immunodeficiency virus). They and others linked this virus to the development of AIDS (acquired immune deficiency syndrome), but a test for exposure to HIV would not become widely available for several more years.

HIV is unusual in that it infects the very cells of the immune system — called T-cells — that protect us from attack by viruses, bacteria and other bugs. Once a person becomes infected, the immune system mounts a counter-attack by producing massive numbers of T-cells. For a time, the virus appears to be contained. Indeed, on the outside, the average HIV-positive person appears no different from an average healthy person.

Yet inside the body of someone with HIV infection rages a vast war, as billions of viruses and T-cells are created and destroyed in a single day. The body cannot sustain the expenditure forever, and the virus slowly gains the upper hand. After 10 years or more of battle the immune system begins to collapse. At this point, infections that are, at worst, annoying for the average person, turn lethal as AIDS develops.

Overwhelmed by wave after wave of infection, the body eventually gives in. Initially considered a mysterious gay plague, researchers now know that HIV is transmitted through unprotected sex, by sharing needles used for injecting drugs, from transfusions of contaminated blood and from breast feeding by infected mothers. HIV has now spread to the point where one per cent of sexually active adults around the globe have the virus.

Epidemic update

A growing number of people are living with HIV, according to a November 2009 United Nations report that also noted that significant progress has been achieved in reducing the number of AIDS-related deaths. Nonetheless, the number of people with HIV is increasing in every region of the world. According to the report:

• There were approximately 33.4 million people living with HIV in 2008 — an increase of 400,000 over the previous year. About 2.0 million AIDS-related deaths were recorded in the same year.
• In 2008, 2.7 million people were newly infected with HIV. Of the total, 71 per cent of the new infections occurred in Sub-Saharan Africa. The report also noted the spread of HIV seems to have peaked in 1996 when there were about 3.5 million new infections.
• Greater access to antiretroviral therapy is helping to expand the lifespan of many people though some regions are continuing to go without. For example, approximately 400,000 infants are born with HIV every year in Africa.

AIDS in Canada

• An estimated 58,000 people had HIV/AIDS in 2006.
• Every two hours, someone in the country becomes infected with HIV.
• More than 27 per cent of infected people don't know they have HIV.
• Women now account for one-fifth of people with HIV/AIDS, up from one-10th in 1995.

Canada recorded its first case of AIDS in 1982. The Public Health Agency of Canada estimates that by the end of 2005, there were about 58,000 people living with HIV-AIDS. Of those, the agency estimates that 15,000 — or just over 25 per cent — don't know it.

In 2009, Thai and American researchers said they had developed an experimental vaccine that appeared to cut the risk of becoming infected with HIV by 31 per cent. (Ramon Espinosa/Associated Press)

The agency says Canada's infection rates have remained relatively stable at approximately 2,500 new cases a year. However, death rates have fallen as medical advances increase the life expectancy of infected people.

The greatest proportion of new infections continues to be among men having sex with men, at 45 per cent. Women accounted for 27 per cent of new infections and now make up more than 20 per cent of the population of people living with HIV-AIDS. But the rate of infection among aboriginals is growing faster than any other group. They accounted for nine per cent of new infections in 2005, an overall infection rate that is nearly three times higher than among non-aboriginals.

Although the number of deaths caused by AIDS has fallen since 1996, Health Canada calls the epidemic "severe and deeply troublesome," and says Canadians should not be complacent.

Dec. 1, 2010, is World AIDS Day. That's the day the AIDS community has chosen, in each of the last 22 years, to raise awareness about the disease. The theme for 2010 is universal access and human rights.

New treatments explored

In September 2009, Thai and American researchers stated they had completed trials for an experimental vaccine that appeared to cut the risk of becoming infected with HIV by 31 per cent.

The research was published online a month later in the New England Journal of Medicine, and presented at a scientific conference in Paris. An editorial published in the journal noted there were still important considerations to be answered, including how long the vaccine's effects last.

In 2007, Ottawa announced a $111-million plan to build an HIV-vaccine plant in Canada. The money was meant to aid more research and assist in possible clinical trials, but in 2010 the federal government cancelled the project.