With no treatment available to prevent the spread of chikungunya, a viral disease transmitted to people by mosquitoes, dozens of teams competed in the CHIKV Challenge to develop the most accurate predictions for cases of the disease for all Western Hemisphere countries and territories.
Hosted by the Defense Advanced Research Projects Agency, which commissions advanced research on behalf of the U.S. Department of Defense, the international competition was launched to accelerate the development of new infectious-disease forecasting methods.
The competition culminated in a win for the University of Arizona.
UA mathematics professor Joceline Lega and collaborator Heidi Brown, an assistant professor of epidemiology in the Mel and Enid Zuckerman College of Public Health, took first place and a $150,000 prize, which will support their ongoing collaboration.
All told, 11 winners were named, receiving a total of $500,000 in prize money, representing institutions that also included the University of Southern California, Johns Hopkins University and the University of Massachusetts.
The win exemplifies the collaborative work of Lega and Brown, the UA's efforts to create proactive measures to minimize the spread of viruses and also the University's interdisciplinary emphasis for solving grand challenges both locally and internationally.
"Our model is extremely simple, which was at first quite surprising," Lega said, adding that she and Brown are now trying to determine if the approach could be used for other epidemics.
Chikungunya, considered a growing public health and national security risk, has been detected in Africa, Southern Europe, Southeast Asia and also islands in the Indian and Pacific Oceans, the U.S. Centers for Disease Control and Prevention reports.
In 2013, the disease was reported for the first time in the Caribbean, the CDC also reported. The Pan-American Health Organization has reported, as of May, nearly 1.4 million suspected cases and more than 33,000 confirmed cases of the virus, noting that it is swiftly spreading in the Western Hemisphere.
"There are two reasons I study these diseases: One reason is because of the public health impact and the other is because of the intellectual challenge," Brown said.
"You can look at number of cases: over a million chikungunya cases in this one outbreak alone, or the 50 to 100 million dengue infections estimated by the World Health Organization to occur each year," Brown said. "If you consider for each of these cases the physical burden, the economic burden on the individual, community or country, if you consider the efforts into vector control — these diseases are having a huge impact globally."
Consider the burden of the West Nile virus. Brown cited research indicating that costs associated with U.S. hospital care and deaths as a result of the West Nile virus, as reported to the CDC, reached about $778 million during a period spanning 1999 to 2012.
During the CHIKV Challenge, scientists and researchers representing 38 institutions were called to produce ways to accurately predict when and where chikungunya — which can result in a fever, joint and muscle pain, swelling, rashes and other symptoms — might appear.
Like the other teams, Lega and Brown were provided weekly reports from the Pan-American Health Organization to develop their predictions, which were then tested against future reports from the organization. Lega and Brown were able to estimate the number, duration and peak of chikungunya cases that occurred in 2014 and 2015 in the Caribbean.
By design, CHIKV Challenge participants were allowed to update their predictions every month as they learned from experience — a challenge structure that sped development of better methods. On average, the top participants succeeded in doubling the accuracy of their predictions every two months relative to their initial forecasts.
"From a mathematical modeling perspective, it was a unique opportunity to develop a model that was based on real data," Lega said.
Brown said mosquito-borne diseases are especially difficult due to the complexity of their systems.
"We try to model the interactions between mosquitoes, pathogens and humans — each adapting, evolving, changing their behavior by both the behavior of the other and the environment in which these interactions exist. Add to that a changing climate," Brown said.
"Any headway we can make in predicting the number of cases, when cases will peak, when an outbreak will end, or how severe an outbreak will be is helpful in reducing the disease burden."