They’re coming!! Black legged ticks

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In an article in the Detroit News, Aug 16, 2015, Erik Foster, Medical Entomologist from the Michigan Department of Community Health stated:

“With certainty and with our research in 2010 and 2014 broad statewide surveys, we found these populations of ticks are moving eastward,” said Erik Foster, a medical entomologist with the Michigan Department of Community Health. “We’ve found blacklegged ticks three blocks from my house in Ingham County. I was really surprised; I didn’t expect to see it so soon.”

For the full article, see Ticks, Lyme disease fears leap in Michigan, Detroit News, Aug 16, 2015

The difference between the maps of incidence of Lyme Disease for Michigan, 2014-2015, on the right, which the HSHV say are about the same is that, in the last year, Calhoun County is now listed as Endemic and Ingham and Jackson county are listed as “potential risk” which means they didn’t meet CDC’s criteria for endemic, but we just heard from the medical entomologist in Ingham County that they found deer ticks within 3 blocks of his house.

2014_Lyme_Risk_MapIngham and Jackson counties are right next door! There are 66 miles between Lansing (where that doctor lives) and Ann Arbor
I drove back and forth from Columbus last week and there were deer and deer carcasses all along the roads. Lyme disease is found in both eastern and northern Ohio. It is 42 miles between Toledo and Ann Arbor.

Are deer to blame?– partially
Ticks don’t start out being infected with Lyme. They get it by feeding on an infected animal, often a mouse or other small rodent. Then, they pass it along to the next animal or person they bite.

Deer ticks need blood to survive. In a typical two year cycle, the tick must have three blood meals. The life cycle begins in the spring of year one. Adults lay thousands of eggs on the ground around the end of May, which hatch into larvae, about the size of a period, in early August. It is at this larval stage that the ticks receive their first blood meal, usually from mice, chipmunks, and birds. This is when the larvae become infected with the Lyme disease bacteria.

After feeding for several days, the ticks become fully engorged and drop off the first host, usually into leaf litter, shrubs or bushes. They remain dormant until the next spring when they molt into nymphs, about the size of a poppy seed. May, June, and July are when the nymphs seeking their second blood meal. They hang out on grasses and bushes waiting for the next host my walk by. While most feed on mice and chipmunks, it is the time of year when pets and humans start spending more time outdoors, and become unsuspecting hosts. Nymphs, the size of poppy seeds now, are very difficult to detect and easily overlooked.

After feeding for four or five days, the nymphs will drop off the host and eventually molt into eight-legged adults. And again they wait, on grasses and shrubs, “questing”, for the next host to come along.

In late summer and through the fall, the adult ticks find their way onto large mammals, usually deer, where they mate.

This is a time when humans and pets are again susceptible to picking up ticks. While still a threat, the adult ticks are larger than the nymphs and easier to see. The females will attach and feed for up to a week, and then drop off and lay up to 3.000 eggs which will hatch in the spring. The two year cycle begins again.

So it is deer, who regularly pick up and serve as taxi, meal and bedroom for the ticks. And deer who provide a good mechanism for the spread of the disease.
And while most deer travel maybe a mile a day, within their home range, during the rut (late fall), some bucks will travel over 10 miles looking for a receptive mate.

From: LYMEinfo and a variety of other known sources, including CDC.

For more information on Lyme Disease, see the Lyme Disease page on this site.

See also the abstract of the 2014 Journal of Medical Entomology article, “The Relationship Between Deer Density, Tick Abundance, and Human Cases of Lyme Disease in a Residential Community,” and download the full article if you want (may require purchase).

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