A brain-eating worm known as rat lungworm has been discovered in San Diego County, the first time the parasite has been found in any state west of Texas.
According to the latest research from the Centers for Disease Control and Prevention, parasites, Angiostrongylus cantonensis, Better known as rat lungworm, first discovered A 7-year-old male Palma wallaby at the San Diego Zoo in December 2024. According to the CDC, the wallaby was experiencing neurological problems, including shaking its head, blindness and stiffness in its limbs. The wallaby died 11 days after diagnosis.
After this discovery, researchers began testing wildlife in and around the San Diego Zoo. From January to February 2025, researchers tested 64 dead wild rats at the zoo. Three of the 64 mice tested positive for lungworm. Meanwhile, researchers were contacted by the Wildlife Rehabilitation Project to report illness in 10 Virginia opossums. The possum was euthanized. Seven out of ten people tested positive for rat lungworm.
Now, findings in opossums and rats lead researchers to believe that rat lungworm has a persistent foothold in San Diego County and has the potential to spread elsewhere.
“However [local infections] Not previously recorded in western Texas, USA, confirmed [rat lungworm] San Diego County wildlife cases provide support one. Guangzhou pine Lungworm can now be considered endemic to this area of Southern California and has the potential to spread to other areas of the continental United States,” the CDC report reads.
The CDC says rat lungworm can be fatal to humans and animals, but death is very rare.
Researchers say lungworm is usually infected by animals or people who eat or handle frogs, small slugs, lizards, mice, freshwater crabs and shrimp.
The CDC recommends residents wash fruits and vegetables thoroughly if rat lungworm is present.
A spokesperson for the California Department of Public Health said in a statement that the agency was not involved in the CDC study and could not confirm the presence of rat lungworm in San Diego or across the state.
CDPH did say, however, that CDC findings suggest the presence of rat lungworm is possible.
“Research in San Diego confirms that this parasite can be transferred from endemic areas to California via infected animals. Because certain snail and slug species present in California are capable of serving as hosts for rat lungworm, and the presence of this parasite in other parts of the state is unknown, certain food safety precautions are recommended. People should not eat any raw or undercooked wild snails or slugs, and all products should be washed thoroughly before consumption,” the report reads. Statement from CDPH to CBS8.
CBS 8 reached out to the County of San Diego to learn more about the presence of rat lungworm in San Diego County. This article will be updated with the county’s response.
watch: What is rat lungworm disease?
