First detection of Rickettsia helvetica in small rodents in Lithuania

Abstract

Rickettsiae are obligately intracellular bacteria with complex life cycles that are transmitted to vertebrates by a variety of arthropod vectors. Although in Europe some studies showed the occurrence of different Rickettsia species in their arthropod vectors, but only few studies have been conducted to identify reservoir hosts for these pathogens. The aim of the present study was to investigate the presence of Rickettsia spp. in different species of small rodents and to assess the potential role of these small mammals in the maintenance of Rickettsia spp. in Lithuania. A total of 334 small rodents belonged to the six species Apodemus flavicollis (n=175), Myodes glareolus (n=111), Micromys minutus (n=37), Microtus oeconomus (n=8), M. agrarius (n=2), and M. arvalis (n=1) were captured with live-traps in different locations in Lithuania during 2013–2014. Spleen samples of small rodents were examined for the presence of Rickettsia DNA by use of PCR targeting partial gltA and 17kDa genes. Rickettsiae were detected in 114 (33.9 %) of small rodents. In total, 37.7 % (66/175) of A. flavicollis, 27.9 % (31/111) of M. glareolus and 45.9 % (17/37) of M. minutus were positive. The sequence analysis shows that Rickettsia isolates from small rodents were 99-100% similar to Rickettsia helvetica sequences deposited in GenBank. This is the first report of Rickettsia helvetica found in small rodents in Lithuania. Our study suggests that rodents may act as reservoir hosts for Rickettsia pathogens.