Contents lists available at ScienceDirect Ticks and Tick-borne Diseases journal homepage: www.elsevier.com/locate/ttbdis Evaluation of the vector competence of six ixodid tick species for Rangelia vitalii (Apicomplexa, Piroplasmorida), the agent of canine rangeliosis João F. Soares a,1 , Francisco B. Costa a,2 , Aline Girotto-Soares b , Aleksandro S. Da Silva c , Raqueli T. França d , Sueli A. Taniwaki a , Bruno Dall’Agnol b , José Reck b , Mitika K. Hagiwara a , Marcelo B. Labruna a, ⁎ a Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, SP, Brazil b Instituto de Pesquisas Veterinárias Desidério Finamor, Eldorado do Sul, RS, Brazil c Universidade do Estado de Santa Catarina, Chapecó, SC, Brazil d Universidade de Caxias do Sul, Caxias do Sul, RS, Brazil ARTICLE INFO Keywords: Ixodidae Amblyomma aureolatum Amblyomma spp. Rhipicephalus sanguineus s.l. Transstadial perpetuation Transovarial transmission Canine piroplasmosis ABSTRACT Rangelia vitalii is the etiologic agent of canine rangeliosis, a severe piroplasmosis that affects domestic dogs in Brazil, Uruguay and Argentina. While R. vitalii is one of the most pathogenic tick-borne pathogens for dogs in the world, its tick vector has remained unknown. The present study evaluated the vector competence of Rhipicephalus sanguineus sensu lato (both tropical and temperate species), Amblyomma aureolatum, Amblyomma ovale, Amblyomma tigrinum, and Amblyomma sculptum for R. vitalii. These six tick species were selected for the study because they comprise the main tick species infesting dogs within the distribution area of canine range- liosis in South America. Acquisition feeding of the above six tick species was performed on domestic dogs showing clinical signs of canine rangeliosis, after being experimentally infected through intravenous inoculation or infestation with R. vitalii-infected ticks. Thereafter, engorged ticks were evaluated for transstadial and transovarial passages of R. vitalii through molecular analysis after molting or oviposition and egg hatching. The resultant ticks were evaluated for their competence to transmit R. vitalii to susceptible dogs. Among the six tick species, only A. aureolatum was able to acquire and perpetuate R. vitalii by transstadial and transovarial passages, as demonstrated by > 5% infection rates of ticks after hatching or molting. When exposed to transmission feeding, only A. aureolatum ticks were competent to transmit R. vitalii to dogs, which became severely ill, and the results confirmed by molecular methods and blood smear examination to have acquired rangeliosis. Results of the present study, coupled with epidemiological data, indicate that A. aureolatum is a natural vector of R. vitalii. Our results also indicate that R. vitalii is the first Piroplasmorida agent to be transovarially transmitted in Amblyomma ticks. 1. Introduction Rangelia vitalii is the etiologic agent of canine rangeliosis, a severe piroplasmosis that affects domestic dogs in Brazil, Uruguay and Argentina (Soares et al., 2011, 2015; Lemos et al., 2012; Eiras et al., 2014; Lemos et al., 2017; Rivero et al., 2017), in addition to native wild canids in Brazil (Soares et al., 2014; Fredo et al., 2015; Quadros et al., 2015; Silveira et al., 2016). For reasons today understood, the disease was mistakenly confused with other diseases for nearly a century, until the completion of the first molecular detection and phylogeny of R. vitalii (Soares et al., 2011). This hemoparasite was described by Pestana (1910) as Piroplasma vitalii, and then reclassified by Carini and Maciel (1914) as Rangelia vitalii due to unique phenotypic characters, such as its ability to parasitize canine leukocytes and vascular endothelium. Paradoxically, these unique characters, coupled with morphological similarities between intraerythrocytic forms of R. vitalii and Babesia vogeli (reported as B. canis), led subsequent authors to doubt the validity of the taxon R. vitalii. Wenyon (1926) hypothesized that the schizontic forms found by Carini and Maciel (1914) were actually a Toxoplasma gondii infection concomitant with a parasitemia by Babesia canis. Three https://doi.org/10.1016/j.ttbdis.2018.05.004 Received 7 March 2018; Received in revised form 27 April 2018; Accepted 3 May 2018 ⁎ Corresponding author at: Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Av. Prof. Orlando Marques de Paiva 87, Cidade Universitária, São Paulo, SP, 05508-270, Brazil. 1 Present address: Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil. 2 Present address: Faculdade de Medicina Veterinária, Universidade Estadual do Maranhão, São Luís, MA, Brazil. E-mail address: labruna@usp.br (M.B. Labruna). Ticks and Tick-borne Diseases xxx (xxxx) xxx–xxx 1877-959X/ © 2018 Elsevier GmbH. All rights reserved. Please cite this article as: Soares, J.F., Ticks and Tick-borne Diseases (2018), https://doi.org/10.1016/j.ttbdis.2018.05.004