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Triple-Threat Ticks

A new study finds that deer ticks can carry other serious illnesses in addition to Lyme disease

by Ann Morrow on July 3, 2014


Babesiosis—ever heard of it? Probably not, but if you’re an outdoorsy type, you need to know that blacklegged ticks, the notorious pest that transmits the bacterium for Lyme disease, can also carry the protozoan that causes babesiosis, a malaria-like disease that infects red-blood cells. Babesiosis produces symptoms similar to Lyme disease with high fever, chills, and nausea and fatigue. It can be fatal to the elderly and people with weakened immune systems.

According to a study published last week by scientists at Bard College, Sarah Lawrence College and the Cary Institute of Ecosystem Studies, deer ticks are almost twice as likely to be infected with two pathogens—the parasites for Lyme disease and babesiosis. The researchers collected thousands of blacklegged ticks from 150 sites in Dutchess County, an area with a high-incidence of tick-borne illnesses (Albany County also has a burgeoning rate of tick-borne disease) and examined their DNA. Almost 30 percent of the ticks were infected with Lyme, and of these a third were infected with at least one other pathogen.

Ticks acquire pathogens from feeding on infected hosts, often mice and chipmunks. Adult ticks also climb up on grasses and bushes and wait for large animals to pass by, including humans. Another emerging pathogen being found in blacklegged ticks is the bacterium that causes anaplasmosis in humans. In addition to symptoms similar to Lyme disease, anaplasmosis can cause hemorrhages.

And there’s more bad news: In New York state, tick transmission is causing a rise in Powassan encephalitis, a formerly rare disease that can result in long-term neurological damage and death. With all these diseases, prevention is the best medicine, and anyone venturing into wooded areas should keep skin areas covered in clothing.

Mice and chipmunks are critical reservoirs for tick-transmitted pathogens, said Richard Ostfeld of the Cary Institute in an e-mail. “Small mammals are often particularly abundant in habitats that have been degraded by human activity,” he said. “That means these patterns of co-infection might get worse as humans continue to impact forest ecosystems.”