"Our findings sharply contrast the gloomy predictions that came out of the International AIDS Conference in Barcelona last month," said Sally Blower, UCLA professor of biomathematics and a member of the UCLA AIDS Institute. "Those statistics calculated that AIDS would claim 65 million lives by 2020."
"Our study found that expansion of drug treatment programs can eliminate HIV on a community level -- even without eradicating HIV in individuals," she said. "It's the first scientific rationale to show that treating more people in developing countries would produce dramatic impact and save substantial numbers of lives."
Blower and her colleagues conducted a new analysis of a previously published mathematical model that focused on the HIV-infected population in San Francisco. They chose the city because it possesses the same high prevalence of HIV as in developing countries, including African nations, where 30 percent of the population is infected.
The research team found that ARV drug therapy benefits both infected and uninfected persons.
"Antiretroviral therapy makes an effective prevention tool," Blower said. "It extends the lives of HIV-infected individuals who take it. It also decreases the number of new infections in the community. The eventual outcome is epidemic eradication."
"It's sort of like having a vaccine out there," she said. "Although the drugs can't cure people, they do decrease the community level of HIV infection. As less people become infected, the epidemic eventually runs out of steam."
According to Blower, the UCLA study suggests that the treatment and prevention of HIV infection are not two entirely different approaches. "Treatment is prevention," she said.
The UCLA mathematical model examined multiple scenarios created by manipulating the value of several different variables, including:
- the number of HIV patients receiving ARV drug treatment
- changes in risky sexual behavior
- the biological fitness of drug-resistant viral strains
- treatment-induced drop in viral load, reducing a patient's ability to infect others
Blower's team discovered that the rate of HIV infection was extremely sensitive to changes in risky sexual behavior. They concluded that any behavioral programs addressing HIV prevention and transmission must be tightly coupled with ARV drug therapy.
Additionally, an increase in risky sexual behavior will worsen the epidemic -- even if drug-resistant strains of HIV are not very fit.
What does this mean for San Francisco? "Our model suggests that it is possible to eradicate HIV in San Francisco," Blower said. "But given the high volume of unprotected sex and drug-resistant HIV strains, it's the worst of all possible worlds and doesn't look good."
Blower and her colleagues offer four recommendations to eradicate the HIV epidemic worldwide:
- Treat more HIV-infected people to reduce the epidemic's severity.
- Develop more effective drugs to reduce viral load. Even a slight drop in viral load would provide great benefit.
- Prevent drug resistance from developing in order to prevent the transmission of drug-resistant viral strains.
- Reduce the rate of risky sexual behavior in order to heighten the overall effect of treatment on the HIV epidemic.
"Expanding treatment programs is the key to eradicating HIV epidemics -- especially in developing countries," Blower said. "Treatment would both benefit the infected individuals and would eventually lead to eradication of HIV in the community."
The study was funded by the National Institute of Allergy and Infectious Diseases and the UCLA AIDS Institute.
Blower's co-authors were Dr. Jorge Velasco Hernandez from the Instituto Mexicano del Petroleo and Hayley Gershengorn from Harvard Medical School.