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Lyme disease has infected over 14% of world population, new study finds

Rates of lyme disease have increased over the past 20 years, and one demographic is most at risk.

For the first time, new research is attempting to delve into exactly how many people have had Lyme disease, and it could be over 14% of the world's population.

The study, published in BMJ Global Health on Monday, is based on 89 studies of the tick-borne illness, and it's the first to measure on a global scale antibodies to the bacteria that cause Lyme disease, Dr. Peter Krause, a senior research scientist at the Yale School of Public Health not involved in the study, told NBC News.

The demographic that's most at risk is men over 50 who live in rural areas. The region where Lyme disease is most prevalent is Central Europe, with about 21% of residents testing positive for antibodies. In North America, the rate was about 9%. The Caribbean had the lowest prevalence at 2%.

Over the past 20 years, rates of Lyme disease have been increasing, researchers found. From 2001 to 2010, 8% of people studied had antibodies, compared to 12% from 2011 to 2021. The trend is likely explained by climate change and deer ticks' preference for warmth and humidity. Summers have also become longer (and winters shorter), and humans are living in closer proximity to wooded areas.

The overall rate of 14% "did strike (me) as a big number," Dr. Natalie Azar, NBC News medical correspondent, said on TODAY Tuesday.

Krause agreed but wasn't entirely surprised. “This is not like, ‘Oh my gosh, there’s so much more disease than we thought there was,’” he said. “These numbers are a bit higher than I would have thought, but this isn’t a revolutionary finding.”

Lyme disease symptoms

Azar added that about three-quarters of people infected with Lyme disease will develop the stereotypical symptoms, making it easier to catch early on. But those who don't receive treatment fast enough "can develop these long, rather debilitating symptoms," she said.

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The typical signs of Lyme disease include a flu-like illness and a red rash that looks like a bull's-eye. "But after that, patients can present with central nervous system (symptoms), fatigue, headache or real, actual neurological deficits." It's also possible to show some symptoms but not develop the characteristic rash.

The most extreme Lyme disease cases can last for months and may result in nerve pain, dizziness, heart palpitations, difficulty breathing and paralysis on one side of the face.

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How to prevent Lyme disease

The best strategy to prevent Lyme disease is to avoid tick bites altogether. Before going outside, use an EPA-registered insect repellent and treat clothing and gear with permethrin. Wear long sleeves and pants, and tuck your pants into your socks. Avoid wooded areas with high grass, walk in the center of trails, and when you come back inside, shower right away and wash your clothes in high heat.