It started with a bizarre burning sensation in her feet. Over the next two days, the searing pain crept up her legs. Any light touch made it worse, and over-the-counter pain medicine offered no relief.

On the third day, the 30-year-old, otherwise healthy woman from New England went to an emergency department. Her exam was normal. Her blood tests and kidney function were normal. The only thing that stood out was a high number of eosinophils—white blood cells that become active with certain allergic diseases, parasitic infections, or other medical conditions, such as cancer. The woman was discharged and advised to follow up with her primary care doctor.

Over the next few days, the scorching sensation kept advancing, invading her trunk and arms. She developed a headache that was also unfazed by over-the-counter pain medicine. Seven days into the illness, she went to a second emergency department. There, the findings were much the same: Normal exam, normal blood tests, normal kidney function, and high eosinophil count—this time higher. The reference range for this count was 0 to 400; her count was 1,050. She was given intravenous medicine to treat her severe headache, then once again discharged with a plan to see her primary care provider.

At home again, with little relief, a family member gave her a prescription sleep aid to help her get some rest. The next day, she awoke confused, saying she needed to pack for a vacation and couldn’t be reasoned with to return to bed. After hours in this fog, her partner brought her to an emergency department for a third time, this time the one at Massachusetts General Hospital.

Getting warmer

In a case report published in the New England Journal of Medicine, doctors explain how they figured out the source of her fiery symptoms—worms burrowing into her brain. By this point, she was alert but disoriented and restless. She couldn’t answer questions consistently or follow commands.

The doctors at Mass General, including a neurologist specializing in infectious diseases, quickly focused their attention on the fact that the woman had recently traveled. Just four days before her feet began burning, she had returned from a three-week trip that included stops in Bangkok, Thailand; Tokyo, Japan; and Hawaii. They asked what she ate. In Thailand, she ate street foods but nothing raw. In Japan, she ate sushi several times and spent most of her time in a hotel. In Hawaii, she again ate sushi as well as salads.

https://arstechnica.com/health/2025/02/burning-in-womans-legs-turned-out-to-be-slug-parasites-digging-in-her-brain/