Raccoon Roundworms (Baylisascaris procyonis) Raccoon Roundworms (Baylisascaris procyonis) may be the perfect biological weapon. The common raccoon is the primary host for this parasite. Not only have urban areas been a windfall for raccoon populations, but the closer proximity facilitates the raccoon-to-raccoon transmission of this worm. Typical rural habitat might contain 10 raccoons per square mile. Prime, bottomland habitat might support 20 raccoons per square mile. Urban habitats have been documented as holding 130-to-390 raccoons per square mile. And, of course, urban habitats increase the exposure of humans to raccoon poop. Baylisascaris procyonis The adult worm on the left is...