New research, led by University of Georgia professor of ecology Vanessa Ezenwa, found that parasites and infections may cause livestock to produce more methane.

“There is evidence that climate change, and warming temperatures in particular, are impacting some infectious diseases and increasing their prevalence,” Ezenwa said. “If that’s happening for livestock diseases, and simultaneously higher prevalence is triggering increased methane release, you could end up with what we call a vicious cycle.”

Methane is a greenhouse gas with an effect on global warming 28-36 times more potent than carbon dioxide. In the past 10 years, atmospheric methane concentrations have increased rapidly, the announcement from the University of Georgia said.

The research team of ecologists, veterinarians and One Health experts formed a working group led by Amanda Koltz, senior scientist in biology at Washington University in St. Louis (Mo.), to study the effects of parasites on ecosystems, including their impacts on climate.

“Infectious diseases impact all animals, but our understanding of how their effects extend to the broader ecosystem is still limited,” Koltz said. “For example, parasite/host interactions can shape host physiology, behavior and population dynamics; some of those impacts are likely to have widespread, cascading effects on ecosystem-level processes.”

The review focused on ruminant livestock, including cows, sheep and goats. The researchers examined data from studies of sheep that showed that animals infected with intestinal worms produced up to 33% more methane per kilogram of feed than uninfected animals, the announcement said.

Infection also causes sheep to grow more slowly, increasing the time to slaughter and thereby increasing total methane emitted by the infected animals, the researchers said.

They also reviewed studies of dairy cattle suffering from mastitis, which revealed that cows with mastitis release up to 8% more methane per kilogram of milk produced than uninfected cows, the announcement reported.

The authors calculated that infectious diseases in ruminant livestock could lead to a sizable increase in methane released into the atmosphere.

The team’s findings highlight the need to take infectious diseases into account when modeling future climate scenarios to ensure that they don’t underestimate methane emissions, the announcement said.

“The vicious cycle between climate impacts on disease and disease impacts on climate is striking,” said co-author Aimée Classen, a professor of ecology and evolutionary biology and director of the University of Michigan Biological Station. “Our study highlights that scientists need to incorporate both animals and disease into the experiments and models used to predict future carbon emissions.”

In addition to Ezenwa, Koltz and Classen, the study’s co-authors include Sharon Deem with the Saint Louis Zoo Institute for Conservation Medicine; David J. Civitello and Matthew Malishev of Emory University; Brandon T. Barton and Zoë E. Johnson of Mississippi State University; Daniel J. Becker of Indiana University; Maris Brenn-White of the Saint Louis Zoo; Susan Kutz of the University of Calgary in Alberta; Rachel M. Penczykowski of Washington University; Daniel L. Preston of the University of Wisconsin-Madison, and J. Trevor Vannatta of Purdue University.

The research was published in the journal Cell.