If deer can spread Lyme disease

Deer are thought NOT to  be able to transmit the pathogen. Therefore, a Borrelia-free tick that feeds on a deer will not pick up Borrelia.

However, they are often the most important host for adult female ticks, and are often termed “tick reproduction hosts” (24).

Therefore, high deer densities are related to higher tick densities, and higher densities of larvae and nymphs feeding on smaller transmission hosts allows more pathogen transmission.

Some studies have found a correlation between deer densities and Borrelia infection (17, 18, 21, 47, 48, 55). However, theoretical studies predict that extremely high deer densities might “dilute” the Borrelia in the tick population, because deer don’t carry it (56) Furthermore, some studies have found no relationship between deer abundance and Borrelia (57, 58).

Therefore, the influence of deer on Lyme disease risk is an area that requires a lot more research.