A SCIENTIFIC study of raccoon roundworm disease conducted in Carmel and Pacific Grove over the last five years has been published by the Centers for Disease Control in the prestigious journal, Emerging Infectious Diseases.

The article, in the December issue, was a peer-reviewed study done by a team lead by San Jose State University biologist William Murray, Ph.D., who spent many months advising the cities of Carmel and P.G. on how to manage their overpopulation of raccoons and how to protect their citizens from the rare but deadly raccoon roundworm (Baylisascaris procyonis) disease.

The study was prompted by the tragic case of 2-year-old Casey Read, the local boy who suffered blindness and severe brain damage after ingesting raccoon feces while playing in his Pacific Grove backyard in 1998. Read was one of 13 severe or fatal cases of raccoon roundworm disease identified in the United States.

Murray explained why his team’s systematic study of raccoon latrines — on roofs, attics, woodpiles, decks, lawns, below forks in tree limbs and other sites the animals habitually befoul — was important to help scientists better understand how the disease is spread to humans.

“Latrines are the source of the infection,” Murray said. “Adult female worms in the small intestine of a single raccoon can produce millions of eggs per day, which are shed in feces. By determining the density and distribution of latrines and the prevalence of viable [roundworm] eggs near human habitation, we learn more about the risk of infection to people, and how to minimize it.”

During 2000 and 2001, Murray and biologists Gabe Roussere and Michael Kutilek examined 127 latrines at private residences in Pacific Grove and 64 in Carmel. They found more than half contained raccoon roundworm eggs. In P.G., 31 percent of the latrines also had infective eggs containing fully formed roundworm larva, which can remain alive in the soil for years and, if ingested, hatch inside a person’s body and begin migrating through brain or ocular tissue, doing devastating neurological damage. A single larva can cause blindness, according to Kevin Kazacos, Ph.D., the Purdue University scientist recognized as the leading expert on raccoon roundworm disease, and a co-author of the study.

“Many roof latrines in Pacific Grove and Carmel were apparently used for years without the homeowners' knowledge,” the report said. “These often accumulated substantial amounts of feces. During periods of rainfall, this fecal matter washes down rain gutters to the ground near residences, thus becoming more accessible to family members." Contamination from a rooftop latrine was blamed for a 2002 case at a Santa Barbara day-care center which severely crippled an 11-month old child.

Since the study was published in early December, Murray said he has received many inquiries from physicians who want to know why there are so few cases of raccoon roundworm disease, if latrines full of infective Baylisascaris procyonis eggs are so widespread.

“It’s pretty evident that you have to have a combination of things — latrines and children at the age when they are crawling around and putting things in their mouths,” he said. “We also have reason to believe that mild infections are unrecognized by parents and undiagnosed by physicians.”

There is no widely available test for raccoon roundworm infection. Suspicious blood samples are routinely sent to Kazacos’ lab at Purdue for definitive diagnosis.

The experts warn parents to watch their children carefully when playing in areas with known populations of raccoon latrines.

“If children are seen to ingest material from a raccoon latrine, the drug albendazole should be administered immediately,” Murray said, “and a sample should be sent for expert examination for Baylisascaris procyonis eggs.” Everyone should thoroughly wash their hands after playing outdoors or working in the yard.

Murray’s best advice for people with persistent raccoons at their home is to discourage the animals by eliminating access where possible, never leaving food out, and removing feces promptly. “The eggs are not infective until they ‘age’ for 14 to 28 days, so if the droppings are cleaned up immediately there is no danger,” Murray said.

The San Jose State University biologists hope to continue their research on raccoons in P.G. in Carmel, and how their parasites impact both humans and other animals. “Severe and fatal central nervous system disease from Baylisascaris procyonis has been reported in more than 90 species of birds and mammals, including endangered sea otters and other marine animals,” Murray said. “We’re hoping for funding to learn more about how they are being infected.”