A brain-eating parasite has been found in San Diego County wildlife for the first time ever, and East County residents are being urged to take action to protect themselves, their families, and their pets.

Rat lungworm (Angiostrongylus cantonensis), a parasitic worm that can cause serious neurological damage in humans and animals, was detected in 10 opossums recovered by wildlife rescuers across the county, including one in La Mesa. The animals were euthanized after developing severe illness. Testing also revealed the parasite in three rats and a wallaby at the San Diego Zoo.

The testing was conducted by the San Diego Zoo Wildlife Alliance in partnership with the Humane Society’s Project Wildlife, the California Department of Fish and Wildlife, UC Davis, and other institutions. Results were published in the Centers for Disease Control’s journal, Emerging Infectious Diseases. Researchers say this is the first confirmed case of rat lungworm west of Texas in the continental United States.

The parasite spreads when rats ingest infected snails or slugs, depositing larvae in their waste. Humans or animals can become infected by consuming infected snails, slugs, or animals that have ingested them, including unwashed produce that has come into contact with slug slime. Symptoms range from headache, vomiting, and fever to seizures, paralysis, coma, and in rare cases, death.

Residents are encouraged to thoroughly wash all fruits and vegetables from gardens, avoid handling snails or slugs with bare hands, eliminate rodent habitat near the home using traps rather than poisons (which can harm birds of prey and pets), and cover outdoor water sources. Despite the findings, neither the California Department of Public Health nor San Diego County Health and Human Services has issued a formal public advisory. The state health department says it is not aware of any human cases in California and that additional surveillance is underway.