Infectious Disease: Evolving Challenges to Human Health

Controlling The HIV Pandemic -- Text-only Version


More than 40 million people around the world are infected with the AIDS virus. Each year about 5 million people are newly infected.

The burden of this pandemic falls most heavily on sub-Saharan Africa, where more than 25 million adults and 3 million children are infected with HIV.

The AIDS pandemic began only 3 decades ago. In this short time, powerful new drugs and treatment programs have been developed to control the disease and reduce mortality from AIDS.

Treatments are complex and costly, and they are life-long. And there is still no cure for AIDS, nor a vaccine to protect against HIV infection. Even so, progress in controlling the pandemic has been dramatic.

Just three years after the first AIDS case was recognized in 1981, initial tests of the antiretroviral agent azidothymidine, or AZT, showed promising results. AZT was officially approved for HIV treatment in 1987.

It was a breakthrough. With regular therapy, the viral load in the body was dramatically reduced and the immune system recovered.

More than thirty new antiretroviral drugs were developed during the 1990s, thanks to the focused efforts of government and academic researchers, clinicians, and the pharmaceutical industry.

Today, these drugs are given in combinations to slow the rate at which HIV evolves resistance to medications.

Global data show a dramatic decrease in AIDS in developed countries where antiretroviral drugs are being extensively used. Even though new HIV infections continue, these drugs enable people in these countries to live with the infection without progressing to AIDS.

Despite rapid progress in developed nations, AIDS remains a threatening burden in many of the world’s poorest countries. Treatment is very costly and often has significant side effects, and drug combinations must be taken faithfully every day to forestall drug resistance.

Providing antiretroviral drugs in these high-infection areas has become a major focus in the global effort to control the disease, and progress is being made.

In Botswana, in 2002, 40% of the nation’s population was estimated to have HIV and the nation risked losing an entire generation. The government recognized the problem and initiated Africa’s first government-sponsored, wide-spread HIV treatment program.

New clinics were established throughout the country, yet the disease carried such a strong social stigma that people were reluctant to be tested and risk getting bad news.

In response, the government instituted routine HIV testing in medical clinics as part of blood screening for all ailments. People who saw doctors for other complaints learned their HIV status, and the number of people who signed up for antiretroviral treatment soared.

Seeing these results, a dozen other African nations instituted HIV treatment programs, and the movement toward global treatment of people with HIV infection is growing.

Even with their high cost and side effects, antiretroviral treatment has changed HIV/AIDS from an untreatable, deadly disease into a chronic infection that many people live with for decades, providing higher quality of life for most people.

Despite these gains, the pandemic continues, with new infections in all countries. The only way to stop the spread is through prevention.

Preventing HIV infection has medical, social, and cultural dimensions. The disease spreads through intimate sexual contact and other blood-to-blood means, such as reusing needles. HIV can also spread from mothers to their infants.

Mother-to-child transmission has been virtually eradicated in the US and Europe, but remains an enormous concern in some African countries where infection rates among pregnant women can reach 20 – 40%. In addition, interruption of mother to infant transmission through breast feeding remains a huge problem in resource poor settings.

Intensive national campaigns to eliminate mother-to-child transmission have shown excellent results.

In Botswana, for example, 39% of pregnant women were HIV-positive in 1999. The government implemented a program to stop mother-to-child transmission and by 2001, 40,000 women were under treatment.

Successful programs rely on intensive government and volunteer support to overcome the parallel challenges of providing a medical infrastructure to test for HIV and distribute medications, and encourage women to be tested despite their fear of the disease and the social stigma that can accompany an HIV-positive outcome.

Campaigns against sexual transmission have shown similar results. In Thailand, for example, where HIV was once rampant among sex workers, the government instituted a program to encourage 100% condom use, which has lowered the transmission of HIV to members of the Thai Army.

In Uganda, where roughly 1/3 of the army was once HIV-positive, government distribution of 160 million condoms per year has virtually halted the sexual spread of HIV in many areas.

The AIDS virus could theoretically be stopped through prevention alone. But, the complex social, cultural, and economic forces that drive the HIV pandemic must be altered.

A vaccine against HIV infection could make the difference. To date, however, such a vaccine has proved elusive.

An ideal vaccine would produce an immune response in people who have never been exposed to HIV. Successful vaccines for other viruses mimic infections without causing disease. Like an infection, a vaccine stimulates immune responses that are tailored to fight off the specific virus.

HIV is continuously undergoing rapid genetic changes and presenting new variations to the immune system.

In fact, the viruses in a single infected person are so genetically diverse that they are not fully recognized by the immune system and not uniformly susceptible to drugs.

Whether immune-based protection is possible remains unknown. There has never been a documented case of complete recovery from HIV infection.

But there are people who seem to survive HIV infection on their own. For reasons that are still being studied, HIV does not destroy the immune systems in these people. Understanding the mechanisms that control HIV infection in this population is a focus of vaccine research.

It may be possible to develop vaccines that enable HIV-positive to maintain healthy immune systems without the aid of antiretroviral drugs. If so, the vaccine would significantly reduce the risk of spreading the virus to others and could contribute to the end of the HIV pandemic.

Many hurdles must be overcome. HIV is unique among infectious diseases because of its genetic diversity, its destruction of immune system cells, and its ability to remain latent inside cells for years before being activated to create new viruses that spread throughout the body.

Vaccines may bring hope to the future. Today, anti-retroviral drugs help extend lives, although the cost is great and side effects can be significant. Prevention of HIV infection remains the only sure protection against this global pandemic.