Two children in California were diagnosed with a rare parasitic infection typically spread through raccoon feces — and occasionally through dogs — according to a new report from the Centers for Disease Control and Prevention (CDC).
The CDC outlined the 2024 cases in its Morbidity and Mortality Weekly Report published on Thursday, July 31. The cases involved two unrelated boys — a 14-year-old and a 15-month-old — who both contracted Baylisascaris procyonis, a roundworm commonly referred to as raccoon roundworm.
This parasite is most often spread through contact with raccoon feces, though rare transmission through dogs has also been documented. The Los Angeles County Department of Public Health (LACDPH) reported both cases occurred in the South Bay area of Los Angeles County.
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According to the CDC, raccoons can shed millions of roundworm eggs daily in their feces. These eggs become infectious after a few weeks and may develop into larvae if consumed by humans or other unintended hosts. So far, only 35 human cases have been reported in the U.S.
In May 2024, the teenage boy — who is autistic and has a history of ingesting non-food items — was hospitalized following notable behavioral changes. Imaging revealed lesions in his brain, and doctors discovered a live parasitic nematode in his eye, which was treated. He was prescribed a six-week course of antiparasitic medication, and his symptoms resolved.
A month later, the 15-month-old boy was hospitalized after an MRI revealed abnormalities in his brain’s white matter. He, too, was later found to have a parasitic worm in his eye, which was treated with a laser. Both children were given albendazole, an antiparasitic drug, and corticosteroids to reduce inflammation.
The exact source of infection for the toddler remains unclear. However, investigators found a raccoon latrine — an area where raccoons routinely defecate — on the roof of the teenager’s home. Positioned directly above the entrance, it allowed feces to roll down onto the landing. It’s believed the teen may have accidentally ingested contaminated soil or feces. Due to repeated raccoon visits and failed cleanup attempts, the family is now considering relocating.
The CDC stressed the potential danger of the parasite: “Given the severity of disease in humans, the high prevalence of B. procyonis infection in raccoons, and the proximity of raccoons to humans and pets, B. procyonis is a substantial public health concern.”
To reduce the risk of infection, the CDC advises the public to:
- Avoid contact with raccoons and their feces
- Refrain from keeping raccoons as pets
- Supervise children or individuals with developmental disabilities to prevent ingestion of contaminated soil or items
- Practice thorough handwashing after outdoor activities
- Safely remove raccoon latrines, especially from flat surfaces like rooftops, decks, tree stumps, and attics
Because dogs can also become infected, the CDC recommends keeping pets from eating raccoon feces and using a year-round parasite prevention treatment.
