Reddish-brown ticks flow steadily these days into the Connecticut Agricultural Experiment Station. They’re being sent by public health officers from across the state who want to know whether Lyme disease is present in their towns, and how fast it’s spreading.

For scientists at the nearly 150-year-old station, tick-borne illnesses are nothing new. Connecticut is the nation’s epicenter for Lyme disease, and it’s where the disease got its name. It was first diagnosed in Old Lyme, Connecticut, in 1975.

But now, the disease is found throughout the United States and cases are increasing.

The spread of ticks and climate change

In the last few years, scientists found that the population of ticks has exploded on the East Coast and throughout the country. During this time, Lyme disease cases have also increased dramatically.

Most recently, there has been an abundance of lone star ticks discovered along Connecticut’s coast.

“During the last two decades, the population of that tick has increased 60 percent,” said Goudarz Molaei, a research scientist at the station. “They have reached the southern part of the state that borders New York City.”

Though the lone star tick doesn’t transmit Lyme disease, its presence far from its usual southern habitat can be interpreted as a microcosm of what is occurring nationwide, Molaei said.

Ticks that carry Lyme disease, like the deer tick, have widened their territory beyond the northeast and into states once thought of as immune.

While nearly all Lyme disease cases are found in 14 states mainly on the East Coast, the disease is also appearing more and more in states not associated with Lyme disease.

Nearly all (95 percent) of Lyme disease cases are found in just 14 states in the U.S. The top five states for Lyme disease cases are Maine, Vermont, Pennsylvania, New Hampshire, and Rhode Island." Credit: U.S. Centers for Disease Control and Prevention

Long, wet winters, a warmer climate, and more people building homes in rural areas are among the reasons why Lyme disease and other tick-borne illnesses are increasing nationwide, experts say.

That means summer travelers need to be aware when hiking or enjoying other outdoor activities, particularly in Connecticut, but also in Delaware, Maryland, Minnesota, Pennsylvania, Virginia, Wisconsin, Northern California, Oregon, and Washington, according to the Centers for Disease Control and Prevention (CDC).

“Generally, the geographic range where ticks and tick-borne diseases are found is expanding,” said Candice Burns Hoffmann, spokeswoman for the CDC. “As people and wildlife move into areas and habitats overlap, they increase their risk of exposure to tick bites and tick-borne diseases.”

How bad is Lyme disease in the U.S.?

There were 26,203 confirmed cases of Lyme disease reported in the United States in 2016, according to the CDC. That represents a 31 percent increase since 2006.

Most Lyme disease cases are reported from May to August. The illness often occurs when a young, infected tick called a nymph bites into skin and transmits bacteria.

The tiny arachnid prefers to attach itself to warm parts of the body, such as a person’s groin, armpits, or scalp.

Different regions have different tick species that carry Lyme disease in varying levels of potency, experts say. In states where the illness doesn’t receive much attention, people infected can be overlooked, said Linda Giampa, executive director of the nonprofit Bay Area Lyme Foundation.

“When we started Bay Area Lyme Foundation five years ago, residents exhibiting symptoms were told by numerous medical professionals that they couldn’t possibly have Lyme disease as ‘there is no Lyme in California,’” Giampa said. “It is particularly upsetting as the numbers increase, and the impact of the disease continues to grow.”

Giampa said the group has seen that sentiment echoed in other parts of the country.

“We have expanded our reach as we realized that the disease is underestimated in the Midwest and South as well,” Giampa noted. “We are consistently surprised by the calls we receive from all parts of the country, and currently offer support throughout the U.S. based on the increasing demand.”

She said one of the challenges for patients seeking treatment is that the strains of the bacteria may vary region to region. As a result, the foundation has created the national Lyme Biobank.

“This bank will allow researchers to explore potential new diagnostics against a range of bacterial strains by providing samples from the East Coast, West Coast and Midwest,” Giampa said. “Because Midwest residents in particular are facing the same struggles we initially faced here in the Bay Area, we are working with local residents in Minnesota and Wisconsin to help overcome these challenges.”

The bacteria can cause flu-like symptoms, including headache and fatigue, and in about 70 to 80 percent of cases it produces a skin rash that often looks like a bull’s-eye, according to the CDC. Most cases can be treated with a few weeks of antibiotics, but if left untreated, Lyme disease can lead to long-term health problems.

Prevention includes using insect repellent before going out and checking pets and children for ticks regularly.