Lyme disease diagnoses are on the rise, and they're happening in places previously "Lyme-free." New research suggests Lyme-carrying blacklegged ticks are quickly colonizing new habitat on the East Coast.

Lyme disease has been diagnosed in 49 states. Almost every state in the U.S. hosts ticks. Lyme disease is especially common in the Midwest and Eastern United States.

But even along the East Coast, there are large pockets thought to be free of ticks. However, new research suggests these tick-free places are quickly disappearing.

In analyzing genetic and phylogeographic data collected from tick populations over the last decade, scientists at the University of Pennsylvania were able to plot migration patterns over the last 30-plus years.

The research -- compiled with the help of scientists at the New York Department of Health and the State University of New York at Albany -- showed that ticks consistently migrate from south to north in short intervals. The northernmost climes are the areas most recently populated, migrating ticks having arrived in the far Northeast some 14 years ago.

Deer ticks, or blacklegged ticks, travel by attaching themselves to migrating mammals and birds.

"We took advantage of samples that had been collected through time to give us a window into the past," lead researcher Camilo E. Khatchikian said in a press release.

"From a control perspective, if you know they are moving extremely easily, you could control them in your backyard but they might be back in a week," Khatchikian explained. "If we want to reduce tick populations over the long term, this means we have to start thinking about more sophisticated approaches."

The research was published in the journal Evolution.

Khatchikian and his colleagues hope to continue their research to better understand what factors -- whether climate change or land use trends -- influence tick migration patterns.