SARCOCYSTIDAE INFECTION IN RODENTS FROM PERIURBAN CONTEXTS

INTRODUCTION: Rodents constitute a notably significant group of mammals, particularly in terms of serving as reservoirs for various pathogens, some of which are of zoonotic concern (Han et al., 2015. Proc Natl Acad Sci U S A, 112:7039-44). Their biological attributes, characterized by elevated reproductive rates, opportunistic behaviors, adaptability, and worldwide distribution, position them strategically, thereby enhancing the likelihood of disease transmission among wildlife, domestic animals, and human populations (Luis et al., 2013. Proc biol Sci, 280:20122753; Han et al., 2015. Proc Natl Acad Sci U S A, 112:7039-44). Rattus spp. and M. musculus exemplify species capable of coexisting within anthropogenically influenced environments. This coexistence raises concerns for potential human health risks due to the close proximity between these species and human habitats. within the scope of this research, we examined the occurrence of Sarcocystidae infections in synanthropic rodents using a broad-spectrum PCR assay targeting the 18S rRNA of Coccidia. MATERIALS AND METHODS: we examined 97 brown rats (Rattus norvegicus), 67 black rats (R. rattus), 47 house mice (Mus musculus), and 1 common shrew (Sorex araneus) collected during pest control programs from urban and rural areas of northern-central Italy, in the provinces of Ferrara, Forlì-Cesena, Ravenna, bologna (Emilia Romagna Region) and Arezzo (Toscana Region). During necropsies, tongue, central nervous system and heart muscle were collected and processed by PCR targeting the 18S rDNA gene, which is generic for Coccidia, followed by sequencing. RESULTS AND CONCLUSIONS: PCR testing yielded positive results in at least one of the examined tissues in 26 R. norvegicus (26.8%), 13 R. rattus (19.4%), and 13 M. musculus (27.6%). Sequencing comparisons using bLAST allowed us to identify four different species of cyst-forming Apicomplexa. In R. norvegicus, the most frequent species was H. hammondi (including H. hammondi-like, characterized by a SNP in the analysed sequence) with a prevalence of 17.5%, followed by Besnoitia sp. at 7.2%; one sequence showed 100% similarity with B. besnoiti. Trailing behind in prevalence were T. gondii at 4% and Sarcocystis gigantea at 2%. For R. rattus, only two Apicomplexan were molecularly identified in the analyzed tissues: H. hammondi/H. hammondi-like (11.9%) and T. gondii (9%). Regarding M. musculus, the most prevalent parasite was H. hammondi/H. hammondi-like (23.4%), followed by T. gondii (4.2%). In one instance, B. besnoiti was detected in a heart sample with 100% sequence similarity. S. araneus tested positive for T. gondii. Rodents from peri-urban and urban environments can act as indicators of environmental contamination by oocysts of apicomplexan parasites with cats as definitive hosts, such as T. gondii, H. hammondi, and S. gigantea, the latter of which has never been previously recorded in rodents. Moreover, the presence of B. besnoiti, a parasite with an unidentified definitive host in Europe, sheds light on the potential role of these hosts as infection sentinels.