The mouse bile duct tapeworm, Hymenolepis microstoma in free-living small mammals in Slovakia: occurrence and genetic analysis

Abstract

SummaryThe mouse bile duct tapeworm Hymenolepis microstoma, is a potentially zoonotic species with a wide variety of reported definitive hosts of rodent genera. In the present study the occurrence of H. microstoma in free-living small mammals in selected areas of Slovakia and the retrospective analysis of epidemiological data published in Slovakia were performed. Hymenolepis microstoma was detected in two animal species, the common shrew (Sorex araneus) and the European hamster (Cricetus cricetus) of 186 small mammals examined from two ecosystems, urban and natural ecosystem of national park. No mention about the presence of this parasite in Slovakia in the past was found following a bibliographical search. Partial sequences of the nuclear paramyosin gene showed the shrew isolate placed in a subclade together with H. microstoma from Portugal, with high bootstrap value for its differentiation from the sister species Hymenolepis nana. Similarly, the analysis of the nuclear ribosomal ITS region placed the hamster isolate in the cluster composed of H. microstoma from Australia, Spain and Portugal. The Slovak isolate was the most distinctive sample among available H. microstoma, differing in 1.4 – 1.9% of nucleotides from the remaining isolates. The difference (seven of 17 nucleotide positions) was partially due to indel polymorphisms associated with two and five nucleotides. To our knowledge, these are the first reports of H. microstoma in Central Europe and also the first record of infection in the common shrew. A recently indicated zoonotic potential of H. microstoma along with a possibility of its direct transmission between animals and/or humans without the need of intermediate hosts pose a public health concern in contaminated areas of Slovakia. The use of molecular techniques may substantially facilitate more thorough understanding of the epidemiological situation of H. microstoma and related tapeworms in various ecosystems of the country.

Perspectives on intestinal tapeworm infections: An evaluation of direct and indirect life-cycles with a special emphasis on species of Hymenolepis

“…In contrast to H. nana , more is known about H. microstoma and the parasite’s full genome has been analyzed ( Cunningham & Olson, 2010 ; Tsai et al., 2013 ). Hymenolepis microstoma adults, whose scolices attach to the bile duct, can survive approximately six months without reinfection ( Jarošová et al., 2020 ). In this species, fully mature tailed cysticercoids develop approximately 11 days after egg inoculation in mice with severe combined immunodeficiency (SCID) ( Andreassen et al., 2004 ).…”

“…Hymenolepis nana (the mouse tapeworm) and Hymenolepis diminuta (the rat tapeworm) are well known zoonotic tapeworms ( Arai, 1980 ). Among the three species, H. diminuta is phylogenetically distant from H. nana and H. microstoma ( Okamoto et al., 1997 ; Jarošová et al., 2020 ). Adult worms of most species in this genus live for one to two years, which typically corresponds to the lifespan of the host rodent ( Arai, 1980 ; Andreassen, 2010 ).…”