Lyme disease case counts are rising across the US. Here’s how much it’s impacting WA

This story and visualization are part of our new “Data In Your Life” series, in which we mine public databases to tell quick stories about the world around us.

Lyme disease is the most prevalent insect borne disease in the country, with far more cases each year than other diseases such as West Nile Virus.

Lyme disease on the rise in US

The U.S. Centers for Disease Control’s (CDC) most recent Lyme disease data is from 2022. In 2022, there were more than 62,000 reported cases of the tick-borne disease, but the CDC estimates that because of under-reporting, the true number of cases each year could be seven times that number.

The prevalence of the disease, which is spread to people through the bite of a blacklegged tick, or a deer tick, has increased dramatically since the U.S. first began tracking the disease in 1991. While better surveillance explains part of the increase, warming climate has also made more of the country suitable for the ticks that carry the disease.

When treated early, Lyme disease symptoms can go away entirely. However, if it is not treated early, the disease can be chronic, with symptoms such as arthritis, fatigue and persistent body aches.

Deer ticks are quickly spreading across the U.S.

Lyme disease case counts have increased as the presence of deer ticks across the U.S. has spread. Since 1996, the number of counties with a deer tick presence has nearly tripled.

While Lyme disease is most prevalent in the northeastern United States, as ticks have spread, so has the disease. In 2022, Vermont had one of the highest numbers of cases per capita with nearly 200 cases per 100,000 people. In 1996, Vermont had only one case per 100,000 people. The Midwest has also seen a significant increase in cases.

Lyme disease in Washington

The west coast typically sees far fewer cases than the northeast and midwest, although the disease is still present.

Washington has seen case counts rise in recent years, although not as much as the rest of the country. According to the CDC , the state saw between 15 and 23 total cases each year between 2008 and 2014. Since then, it’s seen an average of just over 30 cases a year, including two years when the case count reached 43.

That amounts to less than one case per 100,000 people, far below the national average, which reached 18.8 in 2022.

According to the Washington State Department of Health , the majority of Washington’s cases come from a tick bite while traveling out of state . However, some cases stem from the presence of the western blacklegged tick in the western part of the Cascade Mountains.

Lyme disease symptoms and prevention

The CDC advises that people wear long pants and shirts when in tick-infested areas, such as wooded areas or areas with tall grass, and to tuck pants into socks to create a barrier.

The agency advises checking sensitive areas such as armpits and behind ears after spending time outside in one of these areas.

Lyme disease can be identified by a red, circular rash that appears at the site of a tick bite three to 30 days after being bitten. The agency advises going to a health care provider immediately as soon as this type of rash is visible.

Lyme disease is most commonly reported in the spring, summer, and fall, but ticks can be active at any time that the temperature is above freezing.