How health authorities fight the spread of infectious diseases

Public outreach campaigns can prevent the spread of devastating yet treatable diseases such as tuberculosis, malaria and gonorrhea. But ensuring these campaigns effectively reach undiagnosed patients, who may unknowingly spread the disease to others, is a major challenge for cash-strapped public health agencies.

Now a team of researchers at the USC Viterbi School of Engineering has created an algorithm that can help policymakers reduce the overall spread of disease. The algorithm is also optimized to make the most of limited resources, such as advertising budgets.

To create the algorithm, the researchers used data, including behavioral, demographic and epidemic disease trends, to create a model of disease spread that captures underlying population dynamics and contact patterns between people.

Using computer simulations, the researchers tested the algorithm on two real-world cases: tuberculosis in India and gonorrhea in the United States. In both cases, they found the algorithm did a better job at reducing disease cases than current health outreach policies by sharing information about these diseases with individuals who might be most at risk.

The study was published in the AAAI Conference on Artificial Intelligence on Feb. 5. The authors were Bryan Wilder, a computer science graduate student; Milind Tambe, the Helen N. and Emmett H. Jones Professor in Engineering and a professor of computer science and industrial and systems engineering; and Sze-chuan Suen, an assistant professor of industrial and systems engineering.

Our study shows that a sophisticated algorithm can substantially reduce disease spread overall.

Bryan Wilder

“Our study shows that a sophisticated algorithm can substantially reduce disease spread overall,” said Wilder, the first author of the paper. “We can make a big difference, and even save lives, just by being a little bit smarter about how we use our resources and share information.”

Revealing disease dynamics

The algorithm also appeared to make more strategic use of resources. The team found it concentrated heavily on particular groups and did not simply allocate more budget to groups with a high prevalence of the disease.

This seems to indicate that the algorithm is leveraging non-obvious patterns and taking advantage of sometimes-subtle interactions between variables that humans may not be able to pinpoint.

The team’s mathematical models also take into account that people move, age and die, reflecting more realistic population dynamics than many existing algorithms for disease control. For example, people may not be cured instantly, so reducing prevalence at age 30 could mean creating targeted public health communications for people age 27.

“While there are many methods to identify patient populations for health outreach campaigns, not many consider the interaction between changing population patterns and disease dynamics over time,” said Suen, who also holds an appointment as assistant professor in the Leonard D. Schaeffer Center for Health Policy and Economics.

“Fewer still consider how to use an algorithmic approach to optimize these policies given the uncertainty of our estimates of these disease dynamics. We take both of these effects into account in our approach.”

Since transmission patterns for infection vary with age, the research team used age-stratified data to determine the optimal targeted audience demographic for public health communications. But the algorithm could also segment populations using other variables, including gender and location.

In the future, the study’s insights could also shed light on health outcomes for other infectious disease interventions, such as HIV or the flu. In fact, the next step is a trial with public health officials in India to better how the research can translate into real solutions.

The research was supported by MURI Grant W911NF-11-1-0332 and NSF CCF-1522054. Wilder was supported by a National Science Foundation Graduate Fellowship.