Ticks that carry Lyme disease reportedly are spreading across the US

by 1389 on February 18, 2016

in 1389 (blog admin), microbes, PSA

It is time to permit more hunting of the deer that play host to these parasites.

Ixodes scapulares - carries Lyme disease
A blacklegged tick (Ixodes scapularis), one of the main carriers of Lyme disease. Credit: Gary Alpert, Harvard University, Bugwood.org

Live Science has the story:

Here a tick, there a tick, everywhere a tick, tick: The critters that can carry Lyme disease are now more widespread in the U.S. than ever before, according to new research.

In the study, experts mapped the distribution of Lyme-disease-carrying ticks and found that these ticks are ranging farther north than before, and are now living in nearly 50 percent of U.S. counties.

There are two tick species that can carry the Borrelia burgdorferibacteria that cause Lyme disease: the blacklegged tick, also known as the deer tick (Ixodes scapularis), and the western blacklegged tick (Ixodes pacificus). The bacteria can only be transmitted to people through the ticks’ bites. I. scapularis is the primary carrier in the eastern U.S., and I. pacificus is the primary carrier in the far western states.

Researchers previously surveyed these ticks’ distribution in 1998 and mapped the tick populations in the continental U.S. Those results showed that the ticks were present in 34 percent of U.S. counties, across 41 states.

In the new study, they looked at studies and data from state health departments, and reached out to public health officials, Lyme-disease researchers and other scientists. [Video: A Tick Bite Visualized]

For every U.S. county, the researchers evaluated whether tick populations for I. scapularis and I. pacificus were “established” or “reported.” “Established” meant that there was evidence that a population of ticks was alive and well, and reproducing in the county, whereas “reported” meant that a few ticks had been spotted at some point, although not necessarily recently, the scientists said.

After evaluating data for the 3,110 counties in the continental U.S., the researchers found recorded evidence that the eastern tick, I. scapularis, is now reported or established in 1,420 counties and the western tick I. pacificus, is reported or established in 111 counties. Together, the two tick species span 49 percent of U.S. counties across 43 states.

“What we saw was a pretty substantial expansion in the northeastern U.S. in the north central states,” Rebecca J. Eisen, lead author of the study and a research biologist at the Centers for Disease Control and Prevention, told Live Science. The ticks are also expanding farther west and east, she said.

And Lyme cases have been on the rise as well. In 1991, about 10,000 Lyme disease cases were reported in the U.S., but in 2014, more than 33,000 Lyme cases were tallied, according to the CDC. However, some of this increase may be due to more awareness of the disease and more cases being reported. Early-stage Lyme symptoms include fever, chills, joint pain and a distinctive “bull’s-eye” rash at the site of the tick bite. If untreated, the disease can cause arthritis, heart palpitations, brain inflammation, and weakness of the facial muscles, the CDC says.

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