Bobcats Are Back, and They’re Helping Protect People From Zoonotic Disease

Bobcats and other species help reduce the spread of diseases from animals to humans partly because they and other large mammals are poor disease vectors. Bobcats also prey on the small rodents that easily transmit pathogens.

By Christine Woodside

Originally published on Mongabay, 12 November 2024

Humanity has good reason to want to conserve bobcats and other large mammals. Large animals in an ecosystem reduce the spread of disease-causing organisms that can pass from wild animals to humans, a mechanism known as "spill-over" or the dilution effect. One of many examples is the North American bobcat.

Much of the research on the dilution effect has focused on Lyme disease, which is caused by a bacterium prevalent in the U.S. Northeast. Blacklegged ticks (Ixodes scapularis) feed on Lyme disease-infected animals and can pass Lyme to humans when they bite and attach to them.

We continue benefiting from the strong presence of these stealthy small cats in our ecosystems. Their being here lowers the risk of zoonotic disease (those passed from animals to humans), partly because bobcats are poor reservoirs for known diseases, and also because they help control mice, a major disease vector.

Like many mammals, bobcats also carry Lyme disease, yet they are poor at passing along the Borrelia burgdorferi bacteria that causes the disease. In fact, ticks that feed on infected bobcats rarely transmit the Lyme bacteria to the next mammal they bite. The most efficient hosts and vector of Lyme are white-footed mice (Peromyscus leucopus), which almost always do pass on the bacteria to ticks that bite them.

Bobcats feed heavily on the mice, so reduce their populations. In a 2016 study, Felicia Keesing, Levi, Ostfeld and others modeled the dilution effect throughout the ticks’ life cycle. Among the researchers’ conclusions: Bobcats, coyotes and other larger mammals “may reduce the density of small mammals” like mice which are efficient hosts for zoonotic diseases.

“If a tick feeds on a white-footed mouse, it is almost certain to pick up the bacterium,” Keesing said in an interview. But “If it feeds on a bobcat, it is almost certainly not going to pick up the bacterium. It’s not that they [bobcats] don’t get infected, it is that they don’t pass on the bacterium.”

But when large mammals are removed from an ecosystem and biodiversity becomes low, the environment is degraded and “mice are the only thing left,” she added. “The ticks feed on them. And all, or [about] 92% of the ticks become infected. That happens because the other [wildlife] they feed on are not there.”

She underlined the importance of bobcats to ecological well-being, noting that the species is “an integral part of the food chain, controlling prey populations and maintaining the balance in ecosystems.”

You can read the full article here: https://news.mongabay.com/2024/11/bobcats-are-back-and-theyre-helping-protect-people-from-zoonotic-disease/

Cover photo: Wild bobcat photographed in Wichita Mountains National Wildlife Refuge, Oklahoma. Image courtesy of Steve Enter/U.S. Fish and Wildlife Service.