How Will Disease Outbreaks Change as Global Temperatures Rise?

LSU associate professor awarded $2.1 million to study effects of environmental changes on infectious disease dynamics


LSU biological sciences associate professor Bret Elderd recently received a $2.1 million Ecology and Evolution of Infectious Diseases grant from the U.S. Department of Agriculture to investigate how abiotic—physical—factors occurring from environmental changes, like rising temperatures, can shape the coevolutionary dynamics of host-pathogen interactions.

The multi-agency EEID program supports research on the ecological, evolutionary, and social avenues that influence the transmission dynamics of infectious diseases. Elderd will be collaborating with biological sciences associate professor Maheshi Dassanayake and Michael Garvey, a post-doc in Elderd’s lab, as well as Vanja Dukic, an applied mathematician at University of Colorado at Boulder.

“When you look at tightly linked interactions between species, which have evolved overtime, and you change the temperature under which they are occurring, these interactions can also change,” Elderd said. “Over the long term, you may even alter the evolutionary trajectory of these species and their interactions.  We want to understand what part of the interaction between a host and its pathogen will change and the mechanisms driving that change.”

While there is an abundance of research on how different species interactions change under increasing temperatures, scientists know relatively little from an evolutionary perspective about the effects of rising temperatures on species.

The project uses the fall armyworm, an agricultural pest with a wide-spread population, and its species-specific baculovirus. The fall armyworm has a relatively quick life cycle, propelling through generations every 30-40 days. Because of the insect’s rapid life cycle, the researchers can observe potential evolutionary changes through the generations in a smaller, more manageable timeframe than longer-lived species.

“In a previous paper, we looked at how temperature changes affect interactions between a disease and its host,” Elderd said, “and our data show disease transmission actually increases when the temperatures rise. Increases in transmission were driven by changes in individual susceptibility where some individuals were more or less susceptible to the virus.  This occurred over the course of a single outbreak.  Since the host and virus are linked and outbreaks occur quite often, we want to know how these interactions will change over evolutionary time as temperatures increase.   How the host responds along with the virus to changing temperatures are going to be important in determining how it all plays out.”

In addition to tracking the spread of the disease, the researchers will track changes in the host and pathogen transcriptome—the set of all messenger RNA molecules in a cell or population of cells—and genome.

While the baculovirus only affects insects, Elderd said their findings and the associated mathematical models have the potential to be applicable to other viruses besides those that only infect insects.

“We think about diseases in how they infect an individual, and then as they go from the individual to a population, like Baton Rouge, and then as they spread across an even larger area, like Louisiana and beyond,” Elderd said.