Lyme disease study looks at factors that may increase threat
Excerpted from The Poughkeepsie Journal; (07/12/2018)
A new study examining nearly 20 years of data on forests and climate in Dutchess County may shed light on how ecology directly impacts the spread of Lyme disease.
Researchers at the Cary Institute of Ecosystem Studies, a not-for-profit environmental research and education organization based in Millbrook, analyzed the data and found a higher risk of contracting Lyme disease in forests with a larger rodent population and lower numbers of foxes, possums and raccoons.
They also found that tick-borne diseases, including Lyme disease, are closely tied with fluctuating acorn supply and predator communities in forests with many oak trees.
A research team spent 19 years collecting data and monitoring small mammals including mice and chipmunks, as well as black-legged ticks, climate and forests in Dutchess County. Richard Ostfeld, a disease ecologist at the Cary Institute, led the team.
Ostfeld said he hopes the information will help communities and residents determine how to exercise caution when they are outside, whether in their backyards or out in nature.
“Using nearly two decades of data on the forest food web, we were interested in untangling the ecological conditions that regulate the number of infected ticks in the landscape,” said Ostfeld.
The findings were recently published in an issue of Ecology, a journal of the Ecological Society of America.
Key findings included:
- Tick-borne diseases are linked with fluctuating acorn supply and the structure of the predator community.
- Forests with coyotes that lack a mix of bobcats, foxes and possums saw the highest risk of tick-borne diseases.
- Sites with high diversity in predators had lower infection in nymphal ticks – black legged ticks that are the size of a poppy seed – compared to sites dominated by coyotes. Coyotes sometimes displace other predators such as foxes and bobcats that are more effective at controlling rodent populations versus coyotes.
- The number of infected nymphal ticks was lowest at sites with denser forests and a greater diversity of predators.
- Climate impacts Lyme disease since humidity and moisture cause a greater number of infected ticks. Warm, dry spring or winter weather causes a decrease in infected ticks.
Lyme Handbook 
It is nice to see researchers finally focusing on small animals as being the main vector rather than deer. It certainly was a poor choice of names.