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

Abstract

BACKGROUND: The raccoon (), 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 (spp.,spp., andspp.) and to characterizeprotists 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 ofprotists and Cyclophyllidea tapeworms were morphologically characterized using light microscope (LM).species were identified by means ofrRNA,, andsequence analysis. Cyclophyllidea tapeworms were confirmed byrRNA sequence analysis. RESULTS: Microscopic analysis revealed the presence ofparasites and Cyclophyllidea tapeworms in seven (53.8%) of the raccoons examined. Nonematodes ortrematodes were detected in the muscle samples by using an active artificial digestion method. In the small intestine, oocysts and/or sporocysts ofspp. were observed by LM in five of the samples. One species ofcestode was detected in fecal samples of two raccoons. Based on DNA sequence results,was identified in the muscles of a single raccoon from Lithuania. The present study provides the first report of seven distincttaxa identified in raccoon intestines by molecular analyses, including, which forms macroscopic sarcocysts in ducks, and, which infects cattle muscles. Based onrRNA sequencing,was identified in two of the examined animals. CONCLUSIONS: Our findings expand current knowledge on thespecies richness in carnivores. This study also reports the first identification of.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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12917-026-05345-7.