I had a question the other day about roundworms in feral cats. Specifically, how do you deworm a group of cats that you don’t handle and may not be able to catch? There are a few possible approaches, from trapping and treating (oral or topical) to trying to get a dewormer into them via food. Neither is a great option in many situations, because you can’t usually catch all the animals (and feral cats aren’t always the nicest to handle…), or they might not get the proper dose of drug if its given in food.
Baits are a convenient way to treat wild and feral animals, since they are easy to administer and can work quite well. Rabies vaccine baiting has been highly effective in wildlife, and a similar approach could be used for parasite control.
A recent study in Emerging Infectious Diseases (Page et al. 2014) shows the potential usefulness of dewormer baiting for control of the raccoon roundworm, Baylisascaris procyonis, in urban raccoons. The researchers made dewormer baits similar to those used for rabies vaccine, with marshmallow flavoring (don’t ask me why, but raccoons love marshmallows). They mixed a dewormer, pyrantel pamoate, with marshmallow crème, and sealed it in a hollow fishmeal polymer bait container. They then distributed baits in the vicinity of raccoon latrines in suburban Chicago and also tracked a set of untreated latrines. Fecal samples were collected from the environment before and after one year of monthly baiting.
Pre-treatment, B. procyonis was identified in 13% of samples, equally distributed between sites they subsequently baited and sites they did not bait (to act as controls).
After the one year baiting period, B. procyonis eggs were found in 21% of samples from the untreated control sites but only 3% of the treated sites. That’s a pretty dramatic (and statistically significant) difference.
This shows the potential impact of a relatively easy and cost-effective method to deworm raccoons, to reduce contamination of the environment and subsequent human exposure. It couldn’t be a one-shot deal, though. You’d never eradicate the parasite and raccoons will continue to be exposed, even if levels in latrines decrease. So, ongoing baiting would be needed to control the parasite and keep contamination down. That involves more effort and cost, but could be reasonable in high risk areas, such as parks with lots of raccoons and lots of human and pet traffic, or in other areas where elimination of latrines is not practical but there is a reasonable risk of human or domestic animal exposure.
It also raises questions about whether this might be an effective approach for feral cat colonies… stay tuned.