A Cross Sectional Study on Serological Prevalence of Ehrlichia canis and Rickettsia conorii in Different Canine Population of Sicily (South-Italy) during 2017–2019

SIMPLE SUMMARY: Our study provides a picture of Ehrlichia canis and Rickettsia conorii seroprevalence in Sicilian dogs, in the period from 2017 to 2019. E. canis and R. conorii are canine, vector-borne pathogens widespread in the Mediterranean basin infecting humans and a wide variety of domestic and wild animals. The aim of this work was to evaluate the presence of antibody against these two pathogens in dogs and confirm their wide distribution in Sicily. In this study, we reported a prevalence of 29.6% and 53.6% for E. canis and R. conorii, respectively, confirming the widespread distribution of these pathogens in our territory. Temporal variation was found only in R conorii infection, with the highest prevalence (60.6%) reported during 2018. Regarding the spatial variation, the significant difference of seroprevalence was found comparing the climate areas. In particular, the least rainy area showed the higher seroprevalence for both infections. The obtained results suggest that E. canis and R. conorii are present in Sicily in different areas and canine population. Prevention and surveillance of the entire canine population remain the main tools for preventing infection and identifying the areas most exposed to risk. ABSTRACT: Vector-borne pathogens such as Erlichia canis and Rickettsia conorii are widespread in the Mediterranean basin. Rhipicephalus sanguineus, is considered the main vector in Mediterranean climatic areas. Seroprevalence in dogs is variable in relation to environmental factors, presence of vectors, and dogs’ management. We investigated the seroprevalence in Sicilian dogs during 2017–2019, considering temporal as well as spatial variations, and different canine population. A total of 11,009 sera were analyzed: 7568 and 3441 sera were tested to detect antibodies to E. canis and to R. conorii, respectively, by immunofluorescence assay. The rainfall average in the sampling sites during the three-year period was also considered. Statistical analyses were performed using chi-square tests for association between two or more variables. We reported a prevalence of 29.6% and 53.6% for E. canis and R. conorii, respectively. Significant temporal variation was found in R. conorii, while significant difference was found considering canine population and spatial variation regarding both pathogens. Our study updates the previous results of E. canis and R. conorii seroprevalence in dogs in Sicily, and confirms the wide distribution of these pathogens. In addition, we considered, for the first time, three different variables to identify the areas and the canine populations most exposed to risk.