April 23, 2025 – Tick season is back, and so is the threat of Lyme disease, with cases expected to climb yet again as climate change fuels tick activity. But two new studies point to new treatment options on the horizon: Researchers have identified new strategies that could make it easier to stop infection early and also reduce the risk of developing a long-term complication called Lyme arthritis. Here’s what to know.
Lyme Cases Are Expected to Surge in 2025
There’s a good chance new Lyme cases will continue the steep upward trend of recent years. CDC-reported cases jumped more than 40% from 2022 to 2023, possibly due to the effects of climate change – such as shorter winters and rising temperatures, according to the U.S. Environmental Protection Agency.
Ticks that spread the Lyme-causing bacteria Borrelia burgdorferi are most active when temperatures exceed 45 F, and they like a minimum of 85% humidity. Some places in the world where ticks have never previously been found now have them, broadening the risk of contracting the disease.
The First-Line Treatment for Lyme Disease May Change
Researchers at Northwestern University in Illinois recently tested more than 500 antibiotics and other FDA-approved compounds to see if they could treat the infection in a way that attacks the unique cellular features of Borrelia burgdorferi. The findings were published Wednesday in Science Translational Medicine.
In their experiments, an antibiotic from the penicillin family called piperacillin cured mice of Lyme disease using a dose 100 times lower than the current treatment, the antibiotic doxycycline. Doxycycline is known to cause a host of side effects including gut problems because it kills healthy bacteria, too. And it’s ineffective in up to 20% of people. Another limitation is that young children cannot take doxycycline.
“Our recent discovery may provide a new treatment option for Lyme disease that could help patients recover quickly,” minus all those side effects, said study author Brandon Jutras, associate professor in the microbiology-immunology department in the Feinberg School of Medicine at Northwestern University.
However, the treatment would still need to be tested in humans, even though piperacillin is already approved for other uses.
“Those studies are possible and can be fast-tracked with federal funding support, but that support is dwindling for Lyme disease researchers,” said Jutras. “The private sector doesn’t seem to be interested because their profit margins are minimal on a pre-existing, currently available antibiotic.”
Still, his team is investigating its use as a prophylactic after a tick bite but before infection has developed.
Scientists Are Learning More About Lyme Arthritis
One in four Lyme disease cases lead to Lyme arthritis, estimates show (although the CDC says reporting practices may lead to overstating the incidence). The condition usually involves obvious swelling of one or both knees, though it can affect other joints, like the shoulder, ankle, elbow, wrist, or hip. It can emerge long after the initial tick bite and, left untreated, cause permanent joint damage.
In a separate study also led by Jutras and also published Wednesday in Science Translational Medicine, researchers examined the fluid from Lyme arthritis patients’ swollen knees and found bacterial cell wall remnants, called peptidoglycan, months after the initial infection. That’s likely what triggers the arthritis.
“We’re currently developing and testing strategies to target the lingering peptidoglycan,” Jutras said. “If the molecule is eliminated from the body, or the immune system simply no longer responds to the molecule, we may be able to help patients when conventional options have failed.”
Prevention Remains the Best Protection
Though the treatments are improving, avoiding tick bites is still the best defense against Lyme disease, followed by seeking medical attention after a tick bite, even if asymptomatic.
The Johns Hopkins Bloomberg School of Public Health maintains a dashboard that allows users to type a location to see Lyme disease trends by U.S. county or Canadian health region. This can be helpful to consult, including when you’re traveling.
Tick bites don’t always leave a mark, so if you have to remove a tick from yourself, someone else, or a pet, save it and seek medical attention so it can be tested for Lyme. If it’s positive, that doesn’t mean you’ll develop the disease, but close observation is essential.
