People who get bitten by a blacklegged tick have a higher-than-expected chance of being exposed to more than one pathogen at the same time. The new research, published online today in the journal PLOS ONE, was conducted by scientists at Bard College, Sarah Lawrence College, and the Cary Institute of Ecosystem Studies.
This is a female adult blacklegged tick on a scientist's hand.
People who get bitten by a blacklegged tick have a higher-than-expected chance of being exposed to more than one pathogen at the same time. The new research, published online today in the journal PLOS ONE, was conducted by scientists at Bard College, Sarah Lawrence College, and the Cary Institute of Ecosystem Studies.
"We found that ticks are almost twice as likely to be infected with two pathogens-the bacterium that causes Lyme disease and the protozoan that causes babesiosis-than we would have expected," says Felicia Keesing, a professor of biology at Bard College, Adjunct Scientist at the Cary Institute, and co-author of the paper. "That means health care providers and the public need to be particularly alert to the possibility of multiple infections coming from the same tick bite."
Almost 30 percent of the ticks were infected with the agent of Lyme disease. One-third of these were also infected with at least one other pathogen. The agents of Lyme disease and babesiosis were found together in 7 percent of ticks.
The researchers collected thousands of blacklegged ticks from over 150 sites in Dutchess County, New York, an area with 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.
"Mice and chipmunks are critical reservoirs for these two pathogens, so ticks that have fed on these animals are much more likely to be co-infected," says Michelle Hersh, an assistant professor of biology at Sarah Lawrence College, past postdoctoral researcher at the Cary Institute, and lead author of the study.
"Mice and other small mammals are often particularly abundant in habitats that have been fragmented or degraded by human activity," says Richard Ostfeld of the Cary Institute of Ecosystem Studies. "That means these patterns of co-infection might get worse through time as humans continue to impact forest ecosystems."
The researchers also considered another emerging pathogen, Anaplasma phagocytophilum, the bacterium that causes anaplasmosis in humans. Fortunately, ticks were not more likely than expected to be co-infected with Anaplasma and the Lyme disease bacterium.
The researchers determined the proportion of ticks infected with each pathogen individually, then calculated the rates of co-infection expected by chance alone. Not only was co-infection with the agents of Lyme disease and babesiosis greater than expected, but rates of triple infection with the agents of Lyme, babesiosis, and anaplasmosis were about twice as likely as expected. "People in tick-infested parts of the United States such as the Northeast, Mid-Atlantic, and Upper Midwest, are vulnerable to being exposed to two or three diseases from a single tick bite," says Keesing. "And, of course, that risk increases when they're bitten by more than one tick."
Source: Cary Institute of Ecosystem Studies
Beyond the Surface: Rethinking Environmental Hygiene Validation at Exchange25
June 30th 2025Environmental hygiene is about more than just shiny surfaces. At Exchange25, infection prevention experts urged the field to look deeper, rethink blame, and validate cleaning efforts across the entire care environment, not just EVS tasks.
A Controversial Reboot: New Vaccine Panel Faces Scrutiny, Support, and Sharp Divides
June 26th 2025As the newly appointed Advisory Committee on Immunization Practices (ACIP) met for the first time under sweeping changes by HHS Secretary Robert F. Kennedy Jr, the national spotlight turned to the panel’s legitimacy, vaccine guidance, and whether science or ideology would steer public health policy in a polarized era.
Getting Down and Dirty With PPE: Presentations at HSPA by Jill Holdsworth and Katie Belski
June 26th 2025In the heart of the hospital, decontamination technicians tackle one of health care’s dirtiest—and most vital—jobs. At HSPA 2025, 6 packed workshops led by experts Jill Holdsworth and Katie Belski spotlighted the crucial, often-overlooked art of PPE removal. The message was clear: proper doffing saves lives, starting with your own.