Growing blacklegged tick populations = growing incidence of tick-borne illnesses (including Lyme disease)

This spring brought with it predictions of higher tick populations this summer, especially in the Northeast … along with heightened concern of contracting Lyme disease.  Lyme disease is caused by the bacterium Borrelia burgdorferi, which is transmitted by blacklegged ticks as they feed on our blood.  There are several other pathogens that could pass into our bodies as well.

Note: blacklegged ticks is now the preferred name for deer ticks

The short summary of why there may be more ticks in the Northeast this summer:  Two years ago, most oak forests in the Northeast saw a bumper crop of acorns.  This led to higher mouse populations last summer and more blood-feeding opportunities for the ticks.  Higher tick survival set the stage for more ticks this summer. A milder winter may have also helped.

This will be a good opportunity to test how well we can predict tick abundance from the acorn crop of two years ago.  The relationship is pretty well established, and is even more complicated.  Tick abundance is also influenced by chipmunks (and other rodents), deer, gypsy moths, soil moisture, shrub cover, weather, and more.  You can find a good summary of this on the Acorn Connections page of the Cary Institute for Ecosystem Studies website.

Over the past three decades, blacklegged tick populations have been growing swiftly.  Writing in Science, Clair Asher summarizes the finding of one research study (by Eisen et al. 2016) documenting that blacklegged ticks are now present in half of all U.S. counties.  This is a 45% increase in the number of counties where the tick has been found since 1998.

Here are a few of the popular news stories predicting more ticks this summer:

Among the best: Forbidding Forecast For Lyme Disease In The Northeast on NPR

Or try: “Prepare for a Bad Summer for Ticks” published in the Wall Street Journal, but available also on the website for the Cary Institute for Ecosystem Studies.

Why 2017 may be a very bad year for Lyme disease on USA Today

Lyme isn’t the only disease ticks are spreading this summer by WIRED

Featured image via: https://www.cdc.gov/lyme/transmission/blacklegged.html

 

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