Surge in Lyme Disease Predicted for Northeastern US
A rapid decline in mouse populations in the Northeast may have set the stage for a dangerous outbreak of Lyme disease this year.
A leading researcher on human exposure to vector-borne diseases working with the Cary Institute of Ecosystem Studies says that states in the U.S. Northeast may face an increased risk from Lyme disease this year.
Lyme disease is a bacterial infection spread to humans by the bite of the blacklegged tick. Caused by the bacteria Borrelia burgdorferi, the disease occurs in much of the nation, including parts of the West Coast, the Upper Midwest, and New England.
Symptoms of the disease include body-wide itching, chills, fever, headache, and muscle pain and stiffness. Left untreated, within just weeks or months after infection, victims can suffer weakness or paralysis in facial muscles, pain and swelling in large joints such as the knees, and heart problems. Latter stages of the disease may be accompanied by abnormal muscle movement, weakness, numbness and tingling and speech problems, according to PubMed Health published by the U.S. National Library of Medicine.
The key to the reason why states in the Northeastern U.S. may face increased risk from Lyme disease this year is to be found in the ecological interplay between populations of white-footed mice (the preferred host of the blacklegged tick) and the amount of acorns produced by oak trees.
Acorns provide a food base upon which populations of white-footed mice thrive. Heavy production of acorns supports a large population of mice. Oak trees, however, are not consistent producers of acorns, and production varies from year to year, leading to similar fluctuations in mice populations.
"We had a boom in acorns, followed by a boom in mice. And now, on the heels of one of the smallest acorn crops we've ever seen, the mouse population is crashing," said Dr. Richard S. Ostfeld, a disease ecologist with the Cary Institute of Ecosystem Studies in Millbrook, New York.
"This spring, there will be a lot of Borrelia burgdorferi-infected black-legged ticks in our forests looking for a blood meal,” Ostfeld noted. “And instead of finding a white-footed mouse, they are going to find other mammals—like us."
The ticks that transmit the disease to humans are extremely tiny, making detection difficult. According to the Cary Institute, the larval stage of the ticks would have fed on 2011’s mouse population. This spring, as nymphs, they will soon be looking for another meal. “These tiny ticks—as small as poppy seeds—are very effective at transmitting Lyme to people. The last time Ostfeld's research site experienced a heavy acorn crop (2006) followed by a sparse acorn crop (2007), nymphal black-legged ticks reached a 20-year high,” the Institute said in a press release.
A mild winter and early spring mean more people will be enjoying the outdoors just as more ticks may be looking for a meal, leading to a potential increase in Lyme disease.
To protect yourself from the ticks that carry the disease, the Mayo Clinic offers several useful bits of advice. First, when outdoors in areas where ticks may be active, wear long pants and sleeves. When walking in areas with long grass, tuck pants-legs into socks.
Additionally, consider the use of insect repellant. “Apply an insect repellent with a 10 to 30 percent concentration of DEET to your skin and clothing,” says the Mayo Clinic. “Choose the concentration based on the hours of protection you need — the higher the concentration of DEET, the longer you are protected. A 10 percent concentration protects you for about two hours.”
Even if you take these precautions, don’t assume that you have avoided ticks. Upon returning inside, check yourself carefully for any uninvited “guests.” These ticks, notes the Mayo Clinic, “are often no bigger than the head of a pin, so you may not discover them unless you search carefully. It's helpful to shower as soon as you come indoors. Ticks often remain on your skin for hours before attaching themselves. Showering and using a washcloth may be enough to remove any unattached ticks.”
If you do find a tick attached to your skin, the Mayo Clinic suggests removing it carefully using tweezers. “Gently grasp the tick near its head or mouth. Don't squeeze or crush the tick, but pull carefully and steadily. Once you've removed the entire tick, dispose of it and apply antiseptic to the bite area.”