A 20-parasite DNA panel picked up Echinococcus in Pennsylvania's wild canids

A fecal float is a visual test. Fecal material goes into liquid and someone looks for parasite eggs ^[15]. That works when the eggs are distinctive. "Echinococcus eggs in feces look indistinguishable from other common tapeworms," Justin Brown of Penn State said ^[12]. The parasite itself is 2 to 7 millimeters and easy to miss with the naked eye ^[13]. "But when we started using this PCR test, which is very sensitive and identifies parasites by analyzing DNA, we started detecting Echinococcus more frequently," he said ^[14].

The sensitivity claim behind the panel came from a different population. Antech Diagnostics' KeyScreen GI Parasite PCR covers 20 gastrointestinal parasites of dogs and cats, some of them transmissible to people ^[4], and it had already been shown more sensitive than traditional fecal testing in pet dogs and cats ^[5]. Noelle Kuhn, then a Penn State undergraduate honors scholar with a wildlife and fisheries science minor, ran the comparison in wild canids: she performed the floats herself, sent additional samples to Antech for PCR, and did the statistical analysis ^[16][18]. The panel also separated eggs that look identical down a microscope ^[17]. "It was very coincidental that Brown was starting this project and I could hop on board," Kuhn said ^[19].

The three canid groups differ in size, and it matters for reading the numbers. Together they come to 27,302 animals, of which pet dogs are 98.8% ^[22]. One animal is 0.38 percentage points of the wild canid group and 1.7 points of the hunting dog group ^[23][24]. The team had predicted the gradient it found, higher parasite levels in wildlife and lower in pet dogs ^[21].

This does not show whether Echinococcus is becoming more common in Pennsylvania. A more sensitive test finding more infections is a comparison between two methods, and the parasite was identified in the state only recently ^[8]. Brown also said the PCR test has limitations ^[20]. The panel covers 20 parasites ^[4].

The account describes the human end of this and puts no numbers on it. "Echinococcus can pass from wild or pet dogs to humans, where it can cause infections, typically in the lungs or liver, that are complicated to diagnose or treat," Brown said ^[9]. In dogs, wild or domestic, the infection often produces no clinical signs at all ^[2]. The recommendation in the published account is aimed at people. "Although the prevalence of infection in wild canids appears to be low in Pennsylvania, we think it is important that veterinarians, pet owners, hunters and trappers know that this parasite is present in the commonwealth," Brown said ^[10].