The crab-eating fox, Cerdocyon thous (Linnaeus, 1766), (Mammalia: Carnivora) is a medium-sized wild canid with wide geographic distribution from Central (Panama) to the south of South America (Argentina). In Brazil, it is distributed throughout the entire territory except for the Amazon basin (Lucherini, 2015). It is considered a species of least concern for extinction by the IUCN (International Union for Conservation of Nature) Red List of threatened species (Lucherini, 2015). This canid species has nocturnal and crepuscular habits and usually lives in pairs or small groups (Eisenberg and Redford, 1989). It is considered an omnivore, feeding on small mammals, reptiles, amphibians, birds, insects, crustaceans, fruits, and grasses (Pedó et al., 2006). Also, this wild canid plays an important role in seed dispersion and rodent control (Dutra-Vieira et al., 2021; Souza et al., 2021). Furthermore, since crab-eating fox is a synanthropic species and has been recorded concomitantly parasitized by several parasite species (Porfirio et al., 2018; de Souza et al., 2019; Santos et al., 2021), they can act as a bio-accumulators of parasites and may be a great importance in the transmission cycles of parasites in both wild ecotope and in the peridomicile of rural environments (Porfirio et al., 2018).

Piroplasmids and Hepatozoon Miller, 1908 are tick-borne apicomplexan protozoa that parasitize several vertebrate species, which may, in some situations, cause diseases (Smith, 1996; Alvarado-Rybak et al., 2016; Baneth and Allen, 2022). The Order Piroplasmida Wenyon, 1926 comprise four genera (Babesia Starcovici, 1893; Rangelia Carini and Maciel, 1914; Theileria Bettencourt et al., 1907; Cytauxzoon Neitz and Thomas, 1948) and are mainly transmitted by the saliva of ixodid ticks during blood feeding. These protozoa can infect different cells (erythrocytes, lymphocytes, monocytes and endothelial cells) depending on the host species involved (Alvarado-Rybak et al., 2016; Shock et al., 2012; França et al., 2014).

Clinical signs associated with canine piroplasmosis may vary according to the involved agent and the immune status, ranging from subclinical to fatal infections. The main clinical and laboratorial findings associated with piroplasmid infection in canids are fever, anemia, anorexia, lethargy, thrombocytopenia, hemorrhages, and organ dysfunction (Baneth, 2018). These abnormalities are most seen in domestic dogs but reports of symptomatic wild canids have been described (Naor et al., 2019; Phair et al., 2012; Fredo et al., 2015; M de Quadros et al., 2015; Silveira et al., 2016; Copat et al., 2019).

Hepatozoon is a genus composed of more than 340 species that parasitize mammal blood cells and tissues and is transmitted mainly by the ingestion of arthropod vectors containing mature oocysts, albeit other transmission routes (i.e. predation and transplacental transmission) have already been reported (Smith, 1996; Baneth and Allen, 2022; Johnson et al., 2009; Baneth et al., 2013). Two species have been described in domestic dogs and wild canids: Hepatozoon canis James, 1905 and Hepatozoon americanum Vicent-Johnson et al., 1907 (Baneth and Allen, 2022). The former species causes mild, often subclinical infections and has been reported in different continents, while the latter causes more severe infections and has only been described in the USA since the presence of tick vector Amblyomma maculatum Koch, 1844 (Baneth and Allen, 2022). New 18S rRNA genotypes phylogenetically related to H. americanum have been detected in wild canids (Criado-Fornelio et al., 2006; André et al., 2010; Almeida et al., 2013; de Sousa et al., 2017; Millán et al., 2019; Arrais et al., 2021; Carvalho et al., 2021) from South America (Criado-Fornelio et al., 2006; André et al., 2010; Almeida et al., 2013; de Sousa et al., 2017; Millán et al., 2019; Arrais et al., 2021; Carvalho et al., 2021). The main clinical signs associated with Hepatozoon infection in dogs are anorexia, weight loss, pale mucous membranes, pain, diarrhea, vomiting, gait abnormalities, fever, polyuria, polydipsia, anemia, glomerulonephritis, nephrotic syndrome, and thromboembolism (Baneth and Allen, 2022; Da Silva et al., 2011). Few studies reported the occurrence of clinical signs of hepatozoonosis in wild canids (Alencar et al., 1996; Kocan et al., 2000; Trifinopoulos et al., 2016; Zuckerkandl and Pauling, 1965; Tamura et al., 2021). In addition, a putative novel species unrelated to H. canis and H. americanum has been reported in wild canids from Brazil and Argentina (André et al., 2010; Almeida et al., 2013; Millán et al., 2019).

In Brazil, piroplasmids and/or Hepatozoon spp. have been described in the following species of free-living or captive wild canids: crab-eating fox (de Souza et al., 2019; Copat et al., 2019; Criado-Fornelio et al., 2006; André et al., 2010; Almeida et al., 2013; de Sousa et al., 2017; Alencar et al., 1996; Soares et al., 2014), bush dog (Speothos venaticus Lund, 1842) (André et al., 2010), maned wolf [Chrysocyon brachyurus (Illiger, 1815)] (André et al., 2010; Perles et al., 2019), Hoary fox [Lycalopex vetulus (Lund, 1842)] (André et al., 2010) and Pampas fox [Lycalopex gymnocercus (Fischer, 1814)] (de Souza et al., 2019; Fredo et al., 2015; M de Quadros et al., 2015; Criado-Fornelio et al., 2006).

This study aimed to expand knowledge about the occurrence and diversity of piroplasmids and Hepatozoon spp. In C. thous captured in the Miranda Pantanal, Mato Grosso do Sul State, midwestern Brazil.