Every week, Douglas Norris opens a stack of envelopes with gloved hands, pulling a plastic bag from each to hold under a microscope at his lab at the Johns Hopkins Bloomberg School of Public Health. All of them carry ticks — but the excitement lies in figuring out what kind.

“It is a bit like Christmas,” said Norris, an expert in ticks and mosquitos.

Emergency Room visits from tick bites reached an all-time high in May, according to the CDC’s Tick Bite Data Tracker. Experts attribute the surge in ticks to climate change and fragmentation of the environment by urban areas.

“Here in Maryland, you will find ticks or they will find you,” Norris said.

Why it’s important to identify ticks

The specific illnesses that a tick might carry depend on the species. That’s why identifying them can help people understand the risks of their bites.

The Maryland Department of Health receives tick samples from people across the state who are either worried or curious about which species bit them. The agency then sends them to Norris.

He analyzes its shape, the length of its mouthparts, even notes the positioning of its … well, anus. He can also tell how many days it has been feeding by how chubby it is.

Nymph ticks, equivalent to a teenager in human years, are the most responsible for disease transmission, because they are tiny and hard to spot — about the size of a sesame seed.

Dog ticks, deer ticks, and lone star ticks are the most common in the U.S. — the last of which is the most common in Maryland.

Deer ticks are the only tick species that carry Lyme disease, infamous for its bulls-eye rash and potentially lifelong symptoms. A bite from a lone star tick, on the other hand, shouldn’t cause concern about Lyme — but it could bring the risk of Alpha-gal syndrome, which has an unknown incidence rate and inflicts a sometimes fatal allergy to red meat.

“Some people get bitten a lot and they don’t ever develop an allergy, and others develop after a single bite,” Norris said. “Nobody really understands the how or why of that.”

He added that Maryland has more incidents of tick-induced red meat allergies than places like New York, where there are higher densities of ticks.

After Norris identifies the species, he places each — either dead or alive — in vials that pack his freezer.

In the U.S., ticks account for 90% of all diseases from getting bitten by something, including mosquitos. Lyme disease is the “king” of bite-borne diseases, according to Norris. Almost half a million people are diagnosed with Lyme every year nationwide, and many more are likely underreported.

According to the Maryland Department of Health, Garrett County had the highest incidence of Lyme disease in 2023, with about 306 cases per 100,000 people. Prince George’s County had the lowest.

Lyme has a disease infection rate of 30% — meaning every three in ten ticks might carry the illness. Other tick-borne illnesses like Rocky Mountain Spotted Fever, Powassan or babesiosis, are far more rare and deadly.

Across species, ticks are most often found in wooded areas — a hiking trail, a park, or your backyard. All you have to do is walk through them.

Why the uptick?

The Northeast bore the highest number of emergency visits from tick bites of any other region in the U.S. in May, with 283 emergency visits per every 100,000 people — up more than 70 since the same month in 2024, according to the CDC.

The increase in ticks is not unique to this year — it has been going on for decades, according to Nicole Baumgarth, director of the Lyme and Tickborne Diseases Research and Education Institute at Hopkins. She, like Norris, attributed the uptick to climate change and urbanization.

A warming climate extends the period of time that ticks reproduce during the warmer months, and expands the territory in which they are able to live. Ticks can now live in more northern areas than before, Baumgarth said.

Humans are also increasingly coming into contact with areas that were once wooded, according to Norris.

“You look at a map of Columbia, and its humans everywhere with little strips of green space,” Norris said. “All these ticks like those little edges. So as you create more edge, and you have uncontrolled deer populations, I think that’s what really determines numbers.”

Ticks contract the bacteria that cause tick-borne illnesses from mice and other rodents, and deer serve as one of many animals that host the parasites as they move from one area to another.

How to prevent bites and what to do if you are bitten

There are no vaccines and no programs to reduce the number of ticks nationwide — which means the best way to avoid a tick-borne disease is to avoid getting bitten, Baumgarth said.

Thankfully, there are ways to avoid bites and maintain your love of the outdoors. The first step is to be aware.

Before going outside, apply insect repellent and wear pants and a long-sleeved shirt, preferably light-colored, so a dark tick can be easily seen. Don’t be afraid to look dorky and tuck your pants into your socks.

Afterward, check yourself and your loved ones for ticks and take a hot shower.

If you do find a tick, pull it off right away, but don’t squeeze it because it is like a “little balloon” and could release more of its fluids into you, according to Norris.

“Take some fine, fine tweezers, get as close to the skin as possible, and just pull straight up,” he said.

Wash your hands and the bite area afterward, per instructions from the Centers for Disease Control and Prevention.

Lyme disease is the only tick-borne illness that a tick does not transmit immediately upon biting. For “whatever evolutionary reason,” Norris said, you have 36 to 40 hours before Lyme disease transmission occurs, which makes catching the tick early all the more important. When diagnosed early, antibiotics can resolve more than 90% of Lyme symptoms.

Whether you are showing Lyme symptoms or just concerned, Norris recommends consulting a physician.

Finally, zip the tick into a plastic bag and mail it to the Maryland Department of Health for further identification. Chances are the insects will get to pay Norris a visit.