Bumper crop of acorns in 2015 could increase canine Lyme risk in 2017

March 10, 2017

Exploring the connections between white-footed mice, black-legged ticks and four-footed friends.


Anyone who's lived around oak trees knows that acorns are more plentiful some years than others. When they rain down on your roof you'd swear you were in the midst of heavy artillery fire. What you may not know is that lots of acorns in 2015 can lead to more ticks-and tick-borne disease-in 2017.

The Cary Institute of Ecosystem Studies, a Millbrook, New York–based research group that studies the scientific connections among various environmental influences, has taken a hard look at the significance of acorn “mast” years (those seasons when acorn artillery shells pound your roof). What happens, they've found, is that during an acorn boom, white-footed mice feast on the bounty, stock their pantries and emerge the next spring hale and hearty-and explosive in population growth.

The mice, as it happens, are key players in infecting the notorious deer tick, Ixodes scapularis, with the agents that cause Lyme disease, babesiosis and anaplasmosis. Here's how ecologist Rick Ostfeld describes the process in an article on the Cary Institute website:

“The ticks that are emerging as larvae in August-just as the mice and chipmunks are reaching their population peaks-have tons of excellent hosts to feed from. They survive well and they get infected with tick-borne pathogens. And that means that two years following a good acorn crop we see high abundance of infected ticks, which represents a risk of human exposure to tick-borne disease.”

Of course, as veterinarians and veterinary parasitologists know, human exposure means canine exposure as well.

The Cary Institute's predictions are based on 20 years of field studies that have confirmed the relationship among acorn mast years, mouse outbreaks and the prevalence of infected ticks. “Mark your calendars,” the group states-“2017 will likely be a bad year for Lyme disease.”