A study by Ryan J. Monello and Matthew E. Gompper in 2009 entitled Relative Importance of Demographics, Locale, and Seasonality Underlying Louse Underlying Louse and Flea Parasitism of Raccoons (Procyon lotor) published in the Journal of Parisitology 95(1), 2009, pp. 56–62 studied the presence of different ectoparasites on 252 raccoons. The parasites (the Chewing louse (Trichodectes octomaculatus) and the squirrel flea (Orchopeas howardi) have little impact on humans. But their presence may be useful in understanding how other ectoparasites reside on raccoons.
The authors found that males had 3 times as many chewing lice as females and that the lice were found on 50% of all the raccoons trapped. Time of year also played a significant role with 3 times as many lice found in the fall than in the spring. Fleas showed a similar relationship with males carrying more fleas than their female counterparts. But unlike the lice, fleas were significantly more likely to be present in the spring than in the fall.
A biotic factors such as season and behavior of raccoons (i.e. grooming) may have more impact on the presence or absence of parasites than other factors. If this information is indicative of parasites that threaten human-health and safety, wildlife control operators should take greater precautions in certain seasons to protect themselves.