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Raccoon roundworm: Pyrantel pamoate/marshmallow mix shows promise in reducing Baylisascaris prevalence

Baylisascaris procyonis is a roundworm found in the small intestines of raccoons. They excrete the eggs of this parasite in their feces. The eggs can survive in the environment for years under favorable conditions. There can be millions of eggs shed by the raccoon, with high densities in the feces and the soil surrounding it.

Raccoon image/CDC

Humans get infected, albeit rarely (30-something cases have been reported; however, it is probably more common than documented), by accidentally ingesting eggs from the environment, from raccoon feces, contaminated water or fomites. Raccoons typically defecate in favored areas called latrines. Common latrines include the bases of trees, raised forks of trees, fallen logs, rooftops, woodpiles and decks.

At particular risk is young children who play in the yards and frequently put dirt or their fingers in their mouth.

Strategies to reduce the prevalence B. procyonis roundworms required removing all latrines and heat sterilizing (with blowtorches) latrine substrates, very labor intensive activities.

However, in a newly published study in the Centers for Disease Control and Prevention (CDC) journal, Emerging Infectious Diseases, researchers performed a study in the Chicago metro area using a bait made of the deworming agent, pyrantel pamoate and marshmallow creme sealed within the hollow chamber with paraffin wax.

Baits have been used for years to distribute oral rabies vaccine to wildlife populations.

The research team led by lead author, Kristin Page, PhD a biologist from Wheaton College in Illinois sampled 63 raccoon latrine areas in 2012 and determined there was a prevalence of the Baylisascaris procyonis parasitic egg of 13%. One year later, after giving monthly antihelminth baits doses, sampling a raccoon latrine areas showed a significant reduction in parasite prevalence at only 3%.

Dr Page has said in past interviews, “If you deworm the raccoons once a month, then the worms never mature enough to produce eggs”. Eggs are the infectious stage of the raccoon roundworm.

LISTEN: Michael J. Yabsley, MS, PhD, Associate Professor, University of Georgia College of Veterinary Medicine discusses Baylisascaris procyonis

In animal and human infections, the eggs of B. procyonis hatch in the intestine and the larvae migrate through the body. The three most common disease manifestations are larval migrations through the tissues, to the eyes (blindness) and the central nervous system (brain damage).

Treatment for this parasite is generally ineffective in preventing death. If the treatment is started early enough, it could kill the larva before it enters the central nervous system.

How can you prevent this potentially life-threatening infection? According to the Centers of Disease Control and Prevention the following steps should be followed: