Rickettsia species in ectoparasites collected from small rodents in Lithuania

Abstract

Rickettsia species are obligate intracellular gram-negative bacteria responsible for many human infections, causing public health problems in many countries around the world. Rickettsiae are found in association with a wide range of arthropods which feed on very different species of large and small animals. Nevertheless, there are only few studies focusing on investigation of rickettsial pathogens in rodent ectoparasites. This study is the first reports of Rickettsia species in ticks, mites and fleas collected from six different species of small rodents in Lithuania. A total of 1263 ectoparasites were collected from 238 small rodents in Curonian Spit (Lithuania) during 2013-2014. Rodents were found to be infested with Ixodes ricinus ticks (n=578), 5 species of parasitic mites (n=570) from Laelapidae family (Laelaps agilis, Hyperlaelaps microti, Haemogamassus nidi, Eulaelaps stabularis, Myonyssus gigas) and 8 species of fleas (n=115) (Ctenophthalmus agyrtes, Ct. assimilis, Hystrichopsylla talpae, H. orientalis, Megabothris turbidus, M. walkeri, Palaeopsylla soricis, Nosopsyllus fasciatus). Rickettsia DNA was detected in 73.6% I. ricinus ticks, 43.5% fleas and 34.3% L. agilis mites. Infected ectoparasites were found on Apodemus flavicollis, Micromys minutus, Myodes glareolus and Microtus oeconomus rodents. PCR and sequence analysis of partial gltA and 17kDa genes revealed the presence of R. helvetica, R. raoulti in I. ricinus ticks and mites, and R. helvetica and rickettsial endosymbionts in fleas. The results of the study demonstrate high infection rate of spotted fever group rickettsiae in ticks and fleas and suggest that ectoparasitic mites may be reservoirs of pathogenic rickettsiae.