Undetected Infection

Science and Technology @ UCSB

The raccoon that topples your trashcan and pillages your garden may leave more than just a mess. More likely than not, it also contaminates your yard with parasites  — most notably, raccoon roundworms (Baylisascaris procyonis).“If you see a raccoon in Santa Barbara, chances are that it’s full of roundworms,” said Sara Weinstein, a former UCSB doctoral student now at the University of Utah. That is true in varying degrees throughout North America, where urban raccoons may infect people more than previously assumed.
Led by Weinstein, the UCSB researchers wondered if most human infections went undetected. In collaboration with the Centers for Disease Control and Prevention (CDC), they screened blood samples from 150 healthy Santa Barbara residents. Their study, appearing in the CDC journal Emerging Infectious Diseases, found that 7 percent of surveyed individuals tested positive for raccoon roundworm antibodies. That was news to Weinstein, who said the researchers wouldn’t have been surprised if they’d found no evidence of human infection.
According to collaborator Kevin Lafferty, a researcher with the U.S. Geological Survey, “These common — but undetected — infections have unknown health effects in people.”
Over 90 percent of raccoons in Santa Barbara play host to this parasite, which grows to about the size of a No. 2 pencil and can produce over 100,000 eggs per day. “These eggs are really small — about 400 of them can fit on the head of a pin,” Weinstein said. “And soap, alcohol, even bleach won’t kill them.”
These microscopic eggs can survive over a year in the environment, creating a disease risk for hundreds of other animals, including humans. If accidently consumed by a bird, a rodent or a person, the parasite’s eggs can hatch. But, said Weinstein, “they don’t just stay in the gut like they would in a raccoon — instead they migrate through the body.” Sometimes they reach the brain, with potentially ...

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