First report of Atriotaenia tapeworms and Sarcocystis protists in invasive raccoons (Procyon lotor) from Lithuania /

Abstract

Background The raccoon (Procyon lotor), an introduced species in Europe, has exhibited significant population growth and successful adaptation to synanthropic environments over recent decades. In newly colonised areas, knowledge gaps remain regarding various aspects of raccoon ecology, including its behaviour, as well as associated parasites. The majority of pathogens identified in European raccoon populations to date possess documented epizootic and zoonotic potential. The objective of this study was to detect muscle parasites (Alaria spp., Sarcocystis spp., and Trichinella spp.) and to characterize Sarcocystis protists in intestinal scrapings of raccoons, as well as to visually inspect helminth species in six fecal samples. Methods During the 2018-2022 period, muscle, fecal and intestinal samples of 13 animals were examined. Sarcocysts of Sarcocystis protists and Cyclophyllidea tapeworms were morphologically characterized using light microscope (LM). Sarcocystis species were identified by means of 28 S rRNA, ITS1, and cox1 sequence analysis. Cyclophyllidea tapeworms were confirmed by 12 S rRNA sequence analysis. Results Microscopic analysis revealed the presence of Sarcocystis parasites and Cyclophyllidea tapeworms in seven (53.8%) of the raccoons examined. No Trichinella nematodes or Alaria trematodes were detected in the muscle samples by using an active artificial digestion method. In the small intestine, oocysts and/or sporocysts of Sarcocystis spp. were observed by LM in five of the samples. One species of Atriotaenia cestode was detected in fecal samples of two raccoons. Based on DNA sequence results, Sarcocystis lutrae was identified in the muscles of a single raccoon from Lithuania. The present study provides the first report of seven distinct Sarcocystis taxa identified in raccoon intestines by molecular analyses, including Sarcocystis rileyi, which forms macroscopic sarcocysts in ducks, and Sarcocystis bovifelis, which infects cattle muscles. Based on 12 S rRNA sequencing, Atriotaenia incisa was identified in two of the examined animals. Conclusions Our findings expand current knowledge on the Sarcocystis species richness in carnivores. This study also reports the first identification of A. incisa in the feces of raccoons from Lithuania. This study demonstrates that broader sampling and detailed parasitological investigations are essential for a more complete characterization of raccoon parasite diversity