Citation: Ivan, T.; Matei, I.A.; Novac, C.S , .; Kalmár, Z.; Bors , an, S.-D.; Panait, L.-C.; Gherman, C.M.; Ionic ˘ a, A.M.; Papuc, I.; Mihalca, A.D. Spotted Fever Group Rickettsia spp. Diversity in Ticks and the First Report of Rickettsia hoogstraalii in Romania. Vet. Sci. 2022, 9, 343. https://doi.org/ 10.3390/vetsci9070343 Academic Editors: Marisa Masucci and Pamela Martinez-Orellana Received: 6 June 2022 Accepted: 6 July 2022 Published: 8 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). veterinary sciences Article Spotted Fever Group Rickettsia spp. Diversity in Ticks and the First Report of Rickettsia hoogstraalii in Romania Talida Ivan 1 , Ioana Adriana Matei 2, * , Cristiana S , tefania Novac 2 , Zsuzsa Kalmár 2,3,4 , Silvia-Diana Bors , an 5 , Luciana-Cătălina Panait 5 ,Călin Mircea Gherman 5 , Angela Monica Ionică 4 , Ionel Papuc 1 and Andrei Daniel Mihalca 5 1 Department of Semiology, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, 400372 Cluj-Napoca, Romania; talida.holmic@usamvcluj.ro (T.I.); ionel.papuc@usamvcluj.ro (I.P.) 2 Department of Microbiology, Immunology and Epidemiology, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, 400372 Cluj-Napoca, Romania; cristiana.novac@usamvcluj.ro (C.S , .N.); zsuzsa.kalmar@usamvcluj.ro (Z.K.) 3 Department of Infectious Diseases, Iuliu Hat , ieganu University of Medicine and Pharmacy Cluj-Napoca, 400347 Cluj-Napoca, Romania 4 Clinical Hospital of Infectious Diseases of Cluj-Napoca, 400003 Cluj-Napoca, Romania; angela.ionica@usamvcluj.ro 5 Department of Parasitology and Parasitic Diseases, Faculty of Veterinary Medicine, University of Agricultural Sciences and Veterinary Medicine of Cluj-Napoca, 400372 Cluj-Napoca, Romania; silvia.borsan@usamvcluj.ro (S.-D.B.); luciana.rus@usamvcluj.ro (L.-C.P.); calin.gherman@usamvcluj.ro (C.M.G.); amihalca@usamvcluj.ro (A.D.M.) * Correspondence: ioana.matei@usamvcluj.ro; Tel.: +40-728-096105 Simple Summary: Ticks are important parasites that feed on the blood of various host species, representing the most important arthropods transmitting diseases in Europe. Continuous changes in both tick distribution and abundance are related to multiple factors, including climate change. These changes have strong implications for both animal and human health; therefore, continuous surveillance of tickborne diseases is required for an appropriate evaluation of the potential risks faced by animals and humans in a given area. The spotted fever group Rickettsia comprises a large number of zoonotic agents with an increasing importance recognized in the last 30 years. The aim of this study was to evaluate these bacteria in ticks in Romania. Five Rickettsia species were identified in different tick species, with new pathogen–tick associations reported. Rickettsia hoogstraalii, one member of this group, was detected for the first time in Romania and in Rhipicephalus rossicus ticks. This species was first described in 2006 in Croatia, and its pathogenicity is not well known. In addition, the detection of R. raoultii and R. monacensis in unfed larvae of Haemaphysalis punctata reinforce the hypothesis of transmission of Rickettsia from female ticks to larvae; therefore the bite of larvae could pose a health risk. Abstract: Tickborne bacterial pathogens have been described worldwide as risk factors for both animal and human health. Spotted fevers caused by Rickettsiae may cause non-specific symptoms, which make clinical diagnosis difficult. The aim of the current study was to evaluate and review the diversity of SFG Rickettsiae in ticks collected in 41 counties in Romania. A total of 2028 questing and engorged ticks collected in Romania belonging to five species were tested by PCR amplification of Rickettsia spp. gltA and 17-D gene fragments: Ixodes ricinus (n = 1128), Dermacentor marginatus (n = 507), D. reticulatus (n = 165), Rhipicephalus rossicus (n = 128) and Haemaphysalis punctata (n = 100). Five Rickettsia species were identified following DNA sequence analysis: R. helvetica, R. monacensis, R. slovaca, R. raoultii, and R. hoogstraalii. The most common species detected was R. monacensis. Moreover, R. hoogstraalii was detected for the first time in Romania and in R. rossicus ticks. The detection of R. raoultii and R. monacensis in questing larvae of Hae. punctata suggests the possible transovarial transmission of these Rickettsia species in ticks. The detection of R. hoogstraalii for the first time in Romania increases the reported SFG Rickettsia diversity in the country. Vet. Sci. 2022, 9, 343. https://doi.org/10.3390/vetsci9070343 https://www.mdpi.com/journal/vetsci