Diagnóstico, caracterização molecular e epidemiologia da Erliquiose Monocítica Canina na Zona da Mata Mineira, Brasil, e investigação do nicho fundamental da distribuição mundial das linhagens de Ehrlichia canis

Abstract

Tick-borne pathogens are a growing concern amid recent climate changes. Canine Monocytic Ehrlichiosis (CME) in dogs is transmitted by the tick Rhipicephalus sanguineus s.l., with current reports of this parasite infecting non-conventional hosts, including humans. Clinical diagnosis of CME, caused by Ehrlichia canis, is challenging due to the nonspecificity of clinical signs. Immunological and molecular methods are the most commonly used diagnostics, with PCR followed by DNA sequencing being the most accurate method. Although there is a representative number of E. canis strains and R. sanguineus s.l. vectors in genetic databases, studies investigating the diversity, genetic variability, and worldwide distribution of these strains are scarce. Therefore, this study aimed to: 1evaluate the frequency, epidemiology, and hematological alterations caused by Ehrlichia spp. infection in dogs in the southeastern region of Brazil; 2perform molecular characterization of E. canis strains obtained in this study and investigate their genetic relationships with others distributed globally; and 3model the fundamental ecological niche of E. canis and R. sanguineus s.l. in Latin America. The results obtained reveal 1heterogeneity in the frequency of Ehrlichia spp. infection in the southeastern region of Brazil, with frequencies varying according to the sex, breed, and locality of the evaluated animals, as well as different hematological manifestations identified in affected dogs; 2variations within and between localities (continents) regarding the genetic diversity of Ehrlichia canis; and 3similarities between the suitability models for E. canis and R. sanguineus s.l., with key variables being built-up urban areas and the average temperature of the coldest quarter. These results represent a valuable contribution to expanding the understanding of Canine Ehrlichiosis (CE) in the southeastern region of Brazil, with direct relevance to everyday veterinary practice and significant implications for both the epidemiological and genetic understanding of E. canis on a regional and global scale. The integrated approach used in this study is essential for a more comprehensive and effective understanding of the proper management not only of CME but also of other tick-borne diseases in Latin America.