(Inside Science) — Classic summertime scenes of little league games, family hikes and rough and tumble boys exploring the vast continent of their own backyards are all fun and games until someone comes in from their adventure with an unwanted stowaway: the dreaded deer tick. Most of the time, these ticks are a disgusting but minor annoyance. Other times, there is a more serious consequence: Lyme disease.
A little bit of background
About 24,000 cases of Lyme disease are reported in the U.S. each year, and 95 percent of Lyme disease cases in 2012 came from 13 states: Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Vermont, Virginia and Wisconsin.
Why these states? Because lurking in the trees of the northeast and upper Midwest is a great abundance of deer ticks (Ixodes scapularis for the eastern black-legged tick, and Ixodes pacificus for the western black-legged tick), which can carry Borrelia burgdorferi – the bacterium that causes Lyme disease.
By and large, the prevalence of Lyme disease in the U.S. has held steady across the last 10 years or so, but public health officials, especially in the Midwest and northeast, are constantly looking for strategies to lessen the public’s risk of contracting Lyme disease – especially among children.
One solution may lie in a popular pastime during the autumn months.
Johnny, get your gun
A study published in the Journal of Medical Entomology found that the number of reported cases of Lyme disease was strongly related to the white-tailed deer population in the immediate area. After hunting initiatives during the autumn deer hunting season thinned out the white-tailed deer population, the cases of Lyme disease in that area also decreased pretty dramatically.
The 13-year-long study looked specifically at the community of Mumford Cove in Connecticut – one of the states plagued with the most cases of Lyme disease in the country.
In 2000, the community voted to allow controlled deer hunts to trim the deer population in the area, after a ban that lasted many years.
With the introduction of hunting in the community, the deer population began to wane.
Between 1995 and 2008, the researchers asked 90 percent of all permanent residents in the community if they had been diagnosed with Lyme disease, and the number of deer they had spotted in their neighborhood.
An 87 percent reduction in deer density in the area meant a nearly 50 percent reduction in tick infection rates and an 80 percent reduction in resident-reported cases of Lyme disease.
The equation was simple: fewer deer = fewer deer ticks = fewer cases of Lyme disease.
Of course, hunting is not the only way to curtail the deer and thus the deer tick population. The Humane Society of the United States, for example, is looking into a strategy called immunocontraception, which is a birth control method for animals that uses the animal’s immune response to control animal populations.
But, why are only deer ticks to blame for the spread of Lyme disease? Why don’t mosquitoes that also feast on human blood spread Lyme disease?
It is not so much the blood sucking that causes the disease as it is the bacteria carried by the insect. Deer ticks are known to carry Borrelia burgdorferi in the U.S., so they are the ones that can transmit Lyme disease to humans. It’s important to note, however, that not all deer ticks are infected with the bacteria, so not all tick bites will result in infection.
Lyme disease can be difficult to spot right away, especially if the person does not develop a rash at the tick bite site or does not present with symptoms. But when symptoms do occur, they usually present as flu-like symptoms such as fever, chills, fatigue and body aches. If the disease disease progresses untreated it can cause joint pain and neurological problems like Bell’s palsy.
In most cases, an infected tick must be attached for 36 to 48 hours or more before the Lyme disease-causing bacteria is transmitted.
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