Imagine returning from a dream vacation, only to find yourself battling a mysterious illness that leaves doctors baffled.
For one 30-year-old woman from New England, this nightmare became a reality when a parasite she picked up during her travels infected her brain, causing a cascade of terrifying symptoms. What started as a strange burning sensation in her feet soon spiraled into a medical mystery that took weeks to unravel. But what kind of parasite is this? What were her symptoms? How did the doctors find the parasite in her brain? For these and more scary details, read the article.
The First Signs of Trouble
The woman’s ordeal began shortly after she returned from a three-week trip to Thailand, Japan, and Hawaii. At first, she noticed a peculiar burning sensation in her feet, which she brushed off as a minor annoyance.

But within days, the pain spread up her legs, making even the lightest touch unbearable. Fatigue set in, which she initially attributed to jet lag.
When the symptoms persisted, she visited an emergency room, but initial tests came back normal. Days later, the burning sensation spread to her torso and arms, accompanied by a relentless headache. A second ER visit yielded similar results, with no clear explanation for her condition.
It wasn’t until she began experiencing confusion that her partner rushed her back to the hospital, where doctors finally uncovered the shocking truth.
What Was the Parasite in the Woman’s Brain?
Doctors performed a lumbar puncture to analyze her cerebrospinal fluid, which revealed alarmingly high levels of eosinophils—a type of white blood cell that fights parasites. This discovery pointed to a rare condition called eosinophilic meningitis, often caused by parasitic infections. Further testing confirmed the culprit: Angiostrongylus cantonensis, commonly known as rat lungworm.

This parasite, native to tropical and subtropical regions like Southeast Asia and the Pacific Islands, typically infects rodents.
However, humans can accidentally ingest the parasite by consuming raw or undercooked snails, slugs, or contaminated produce. Once inside the body, the larvae can migrate to the central nervous system, causing inflammation in the brain and spinal cord.
A Race Against Time
The woman’s case highlights the challenges of diagnosing and treating parasitic infections. Rat lungworm symptoms can range from mild headaches to severe neurological damage, and in rare cases, the infection can be fatal. Fortunately, after a 14-day course of antiparasitic medication and steroids to reduce inflammation, the woman recovered and was discharged from the hospital.
What is the Rat Lungworm?

Rat lungworm is a parasitic nematode that primarily infects rodents, but can also pose a serious threat to humans. The parasite’s life cycle begins in rats, where adult worms lay eggs that hatch into larvae. These larvae are excreted in the rat’s feces and then ingested by snails, slugs, or other intermediate hosts like freshwater shrimp or crabs.
Humans can accidentally become infected by consuming raw or undercooked snails, slugs, or contaminated produce. Once inside the human body, the larvae can migrate to the central nervous system, causing eosinophilic meningitis—a rare but severe inflammation of the brain and spinal cord.
Symptoms range from headaches and nausea to confusion, tingling sensations, and even paralysis. While the parasite cannot mature or reproduce in humans, its presence in the nervous system can lead to long-lasting or life-threatening complications if not treated promptly. This makes rat lungworm a significant concern, especially in tropical and subtropical regions where the parasite is endemic.
How to Protect Yourself?

Rat lungworm infections are preventable with proper precautions. The CDC advises against eating raw or undercooked snails, slugs, or freshwater shrimp, and recommends thoroughly washing produce in areas where the parasite is endemic.
Wearing gloves while gardening and washing hands after handling snails or slugs can also reduce the risk of infection. It is of great importance to stay vigilant, especially when traveling to regions where parasites like rat lungworm are prevalent.