When inequality pays dividends

When there are limited treatments for serious diseases, such as bird flu and HIV-AIDS, city residents should be first in line for the drugs ahead of those in rural areas to most effectively contain the risk to the community, according to research led by a University of New South Wales (UNSW) academic.

The researchers focused on the HIV-AIDS crisis in South Africa, finding that a quarter of its AIDS-related deaths and infections could be averted within four years, if the limited supply of anti-retroviral therapies is distributed inequitably.

"The South African government is facing a moral dilemma," said the first author of the research, Dr David Wilson, who is now based at the Centre for Vascular Research (CVR) at UNSW, after completing the work at UCLA with another of the paper's authors, Professor Sally Blower. "We have shown it is most efficient to distribute the drugs to the cities only, leaving rural areas even more disadvantaged."

"If it is implemented in South Africa, our strategy will save a large number of lives in the short-term and this trend will further magnify in years to come," said Professor Blower, the senior author of the research.

"The methodology in this paper can also be very easily applied to other settings and also other diseases such as influenza vaccination, including the potential emergence of bird flu," said Dr Wilson. "Even in Australia and the United States there are not enough flu vaccines for everyone, if a virulent case appears. Concentrating the distribution of drugs in the cities would be far more effective at containing the outbreak."

The findings, which have just been published in the prestigious journal, Proceedings of the National Academy of Science (PNAS), have shown that if this strategy had commenced in South Africa in 2004, 1,400 lives would have been saved and 15,000 new infections would have been prevented by 2008 in one province of the country alone.

The researchers used mathematical modelling, based on figures from the KwaZulu-Natal province and its capital, Durban, to make this conclusion. KwaZulu-Natal is the South African province with the largest population (9.4 million) and the highest prevalence of people living with HIV-AIDS (approximately 21 percent of all South African cases, or almost 2 million people).

"Durban acts as a major hub in the province, so reducing transmission in the main city will most effectively contain the problem," stated the authors. "Up to 46 percent of infections in Durban would be prevented, but generally less than 5 percent in rural areas will be prevented."

"We also had a surprise finding," said Professor Blower. "This strategy will have the lowest levels of transmitted drug resistance overall."

"Most people receive the therapy and respond to it, but the HIV virus mutates and eventually becomes resistant to the treatment, so they have to go onto another therapy," said another author, Dr Jim Kahn, University of California at San Francisco and San Francisco General Hospital. "These drug-resistant strains can be transmitted to other people, disqualifying the use of first-line treatments".