Brain-Eating Parasite Found In CA For The First Time. What You Should Know

SAN DIEGO, CA — California health officials are sounding the alarm after a brain-eating parasite first found in China has been detected in San Diego County for the first time.

The discovery in San Diego County is the first time the disease has been detected in a state west of Texas.

The parasite dubbed "rat lungworm" was found throughout San Diego County in ten possums wildlife rescuers retrieved after they became ill. The disease was also found in three rats and a wallaby at San Diego Zoo. Most of the confirmed cases of rat lungworm appeared in 2025, according to the CDC report.

The parasites are commonly found in the lungs of rats, which can cause them to cough and swallow worm-filled sputum. The worms' larvae are later transmitted through rat droppings that are consumed by snails, slugs or other animals. The disease can also be contracted after an animal or human eats an animal that has been infected, or consumes slime from an infected snail or slugs, and contaminated produce. Frogs, possums, and freshwater crabs are also known to host rat lungworm.

According to the CDC, the risk of transmission of lungworm to humans is low, but can bring on serious symptoms and illness if contracted, including meningitis, and neurologic issues, such as headaches, as well as fever, stiff neck, sensory changes, nausea, and possibly death.

The researchers said rat lungworm is "an emerging veterinary and public health concern."

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The discovery of Angiostrongylus cantonensis, also known as "rat lungworm," in San Diego County was documented in a study provided by San Diego Zoo Wildlife Alliance and published last month in a report released by the Centers For Disease Control and Prevention.

Rat lungworm was first discovered in China in 1935 and spread to the south and east coast of the United States in the 1960s. The disease has since been found in Florida, Hawaii, Louisiana, Georgia and Texas.

No human cases have been identified so far in California. Nationwide, researchers have recorded more than 220 confirmed cases, The Washington Post reported. Most U.S. cases have been contracted in Hawaii followed by Southern states where the disease has been known to circulate in rodents. Infections have been linked to eating unwashed vegetables exposed to snails and slugs and to toddlers crawling in the dirt in infected areas.

In one fatal case cited by The Washington Post, an Australian rugby player ate a slug on a dare from his friends in 2010 and fell into a coma. The disease left him paralyzed, and he died eight years later.

To prevent infection and the spread of rat lungworm, the CDC advises people to thoroughly wash fruits and vegetables, especially if they have been exposed to snails or slugs. Also, avoid eating raw or undercooked snails, frogs, freshwater crabs, prawns, or slugs. Drinking from garden hoses, which may have had contact with snails or slugs, should also be avoided.