Tick bites pose risk of multiple infections, says study led by SLC faculty member

A new study conducted by a team of scientists including SLC biology faculty member Michelle Hersh, lead author of the study when she was affiliated with Bard College and the Cary Institute of Ecosystem Studies, reveals risks of exposure to multiple pathogens from tick bites. 

Published June 18 online in the peer-reviewed scientific journal PLOS ONE, the study focuses on co-infection of blacklegged ticks. People bitten by these ticks have a higher than expected chance of being exposed to more than one pathogen at the same time. Importantly, ticks were nearly twice as likely to be infected with the pathogens that cause Lyme disease and human babesiosis than expected due to chance alone. “Both medical practitioners and local residents should be aware of the risk of co-exposure,” said Hersh.

The researchers collected thousands of blacklegged ticks from over 150 sites in Dutchess County, NY, an area with a high incidence of tick-borne illnesses. They also collected ticks that had fed on different kinds of wildlife, including birds, rodents, opossums, and raccoons. Ticks acquire pathogens from feeding on infected hosts. DNA from each tick was extracted and tested for the presence of several pathogens. Almost 30 percent of the ticks studied were infected with the agent of Lyme disease. One-third of those were also infected with at least one other pathogen. The agents of Lyme disease and babesiosis were found together in seven percent of the ticks.

“Mice and chipmunks are critical reservoirs for both the bacterium that causes Lyme disease and the protozoan that causes babesiosis, so ticks that have fed on these animals are much more likely to be co-infected,” said Hersh.

The researchers also considered another emerging pathogen, the bacterium that causes anaplasmosis in humans, but fortunately ticks were not more likely than expected to be co-infected with Anaplasma and the Lyme disease bacterium.

Read the study»