Lyme Disease-Carrying Ticks Rapidly Spreading Across Midwest

Charlie Plain | June 29, 2017
Jonathan Oliver
Assistant Professor Jonathan Oliver

Each year, 300,000 Americans contract Lyme disease, which can lead to any number of long-term health issues such as arthritis and neurological problems. Lyme disease is caused by a bacterium that is transmitted by the bite of the blacklegged tick, also known as the deer tick. A new study by the School of Public Health shows deer ticks are rapidly expanding across the Midwest, and increasingly, more ticks also carry the Lyme disease-inducing bacteria.

“From a public health standpoint, Lyme disease has significant morbidity issues because it makes people really sick,” says lead author and Assistant Professor Jonathan Oliver, a public health entomologist who specializes in studying the deer tick. “In addition to making people feel awful, the cost to the economy is in the billions because people miss a lot of work or can’t be as productive.”

The study was recently published in the Journal of Medical Entomology.

“Over the past 20 or so years, the range in which you can find the tick has really been expanding across Iowa, Minnesota, and the Midwest,” says Oliver. “In Iowa, which this paper covers, the ticks were initially found mostly in the Northeast corner of the state. Over the past 24 years, they’ve managed to skip and hop across the islands of forest habitat in the corn fields and are now found in two-thirds of Iowa’s counties.”

Experts speculate that the ticks’ spread is being aided by a variety factors including climate change, reforestation, and a huge white-tailed deer population to carry them across Iowa.

As the ticks range further across the state, they are also carrying more disease.

“We’re seeing a big, rapid increase in the proportion of ticks that are infected with the bacteria that causes Lyme disease,” says Oliver. “In 1998, only about 8 percent of deer ticks were infected with the bacteria. By 2013, 23.5 percent of the ticks were carrying the bacteria — that’s nearly 1-in-4 of the ticks that can end up on your body.”

Oliver says the results show that ticks and tick-borne disease are only going to become a bigger problem in the U.S. His advice is to focus on education and prevention efforts to stop the ticks from spreading disease.

“Treatments for Lyme disease are effective, but diagnosing it is still really difficult,” says Oliver. “Take basic preventative measures: When going into forested areas wear long pants, use insect repellant containing DEET, and perform daily tick checks on your body.”

The researcher also recommends increasing federal funding for tick and tick-borne research to help meet the threat from their rapid expansion across Iowa, and the nation in general.

Oliver is continuing to research the topic by examining the bacteria found inside ticks in terms of how they interact with each other and where they are found in the landscape.

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