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    Lyme Disease: What To Know This Season

    May 20, 2016 -- The tick responsible for Lyme disease is showing up in new areas in the U.S., a worrisome trend.

    Although the majority of cases are still reported in the Northeast, the black-legged tick -- also known as the deer or bear tick -- has been found as far south as Florida and as far north as Canada, data from the CDC show.

    And while experts say it’s impossible to forecast how bad this tick season from about spring to winter will be, cases have been trending upward - doubling nationwide between 1995 and 2014.

    CDC epidemiologist Paul Mead, MD, says there’s been a steady, gradual increase in cases of the disease and the areas where the ticks live. “It’s like a bomb going off; it’s spreading in all directions,” says Mead, chief of epidemiology and surveillance activity, Bacterial Diseases Branch.

    For most people, the disease causes flu-like symptoms. About 80% of people who get it fully recover by taking antibiotics, says John Aucott, MD, of the Johns Hopkins Lyme Disease Clinical Research Center.

    Mead and Aucott shared more about the disease and what to expect this year and beyond.

    What’s driving up Lyme numbers?

    A worldwide warming trend has made more northern areas like Canada, Maine, and Minnesota hospitable to ticks.

    But the number of deer -- which carry the ticks -- probably plays a bigger role, says Mead. “Land use, forestry growth, and how many people develop homes in areas with large deer populations are among the factors driving this long-term trend,” he says.

    Public health officials report between 30,000 and 36,000 cases of the disease a year (although experts believe the number is closer to 300,000). The ticks are most active in May, June, and early July, Mead says.

    Where is the black-legged tick population concentrated?

    The Northeast continues to have the most concentrated areas of Lyme cases. But the black-legged tick is now present in nearly half of U.S. counties in 43 states, a jump of nearly 45% since 1998, according to a recent CDC report. The majority of the tick population growth has been in the North-central and Northeast.

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