Prepare for a sharp increase in Lyme disease infections in the northeastern U.S., epidemiologists announced Thursday. Researchers blamed the predicted disease surge on an acorn shortage and not the most recent mild winter.
Acorns are the primary food of white-footed mice, animals that provide Lyme-disease-carrying ticks with nourishing blood. As acorn crops decrease, so decrease mice populations along with the food source for Lyme-associated ticks. The ticks then have to search for new sources of food, including humans.
On the heels of one of the smallest acorn crops we've ever seen, the mouse population is crashing, Richard Ostfeld, a disease ecologist at the Cary Institute of Ecosystem Studies, said in a statement. This spring, there will be a lot of [Lyme disease]-infected black-legged ticks in our forests looking for a blood meal. And instead of finding a white-footed mouse, they are going to find other mammals - like us.
A booming crop of acorns in the 2010/2011 winter season set the stage for a record number of ticks at the nymph growth stage for the 2012 spring season, researchers said. Ticks feed only three times throughout their lives: as larvae, nymphs and adults. Ticks transmit the bacteria that cause Lyme disease, Lyme borreliosis, most effectively at the nymph stage.
The last time the northeastern U.S. experienced a heavy acorn crop followed by a shortage, in 2006 and 2007, the number of nymphal ticks reached a 20-year high, Ostfeld, who has tracked the relationship between acorns, mice and ticks for more than two decades, said in a statement.
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The Centers for Disease Control and Prevention counted more than 30,000 confirmed cases of Lyme disease in 2010, the majority of which occurred in the northeastern U.S. A heavy acorn crop followed by a shortage can increase the number of infections by 67 percent as in the case of the 2006/2007 season.
Lyme disease, transmitted by black-legged ticks such as deer and bear ticks, is named for Lyme, Conn., the town where researchers first identified the disease in 1975. Lyme disease causes symptoms such as fever, headache and fatigue, but the classic sign is a bull's-eye rash that can occur between three and 30 days after the tick bite.
If symptoms are left untreated, the disease eventually causes neurological problems such as impaired muscle movement, inflammation of the membranes surrounding the brain and temporary facial paralysis.
The best prevention against Lyme disease is wearing protective clothing such as hats, long-sleeved shirts and long pants when walking through areas where the disease is prevalent, according to the Mayo Clinic. Wearing light colors makes ticks more visible when stuck to clothing.
Lyme disease is treated with antibiotics such as doxycycline and amoxicillin for 10 to 28 days. Lyme disease is usually curative with no lingering problems if treated early. If left untreated, the disease can be more stubborn, and may require an antibiotic that has the ability to cross the blood-brain barrier.