Spatial Analysis of Infections by Toxoplasma gondii and Neospora caninum (Protozoa: Apicomplexa) in Small Ruminants in Northern Italy

SIMPLE SUMMARY: Toxoplasma gondii and Neospora caninum are among the major abortifacient pathogens in sheep and goats. Environmental risk factors may contribute to the spread of both protozoans among sheep and goats. In this study, the spatial analysis provided additional information useful to study the patterns of distribution and spread of diseases, increasing the comprehension of the association between disease processes and explanatory environmental variables. The research aimed to explore whether geographical or environmental factors could influence the infections by T. gondii and N. caninum in sheep and goats in northern Italy and identify areas at risk of infection. A heterogenic distribution of seroprevalence both pathogens was highlighted in the study area with areas at high or low risk according to the protozoan. Particularly, annual temperature, rainfall, and their association enhanced the risk of T. gondii and N. caninum infection among sheep. Otherwise, the risk for goats to acquire those infections did not depend on environmental or geographical features, but instead on factors associated with individual characteristics or farm management. The results observed in this study suggest spatial analysis is a useful tool to implement control measures to prevent these important protozoan diseases for small ruminant breeding. ABSTRACT: The objectives of this study were: (i) To investigate possible geographical or environmental factors influencing the infections by Toxoplasma gondii and Neospora caninum in sheep and goats in northern Italy; (ii) to identify areas at risk of infection to set up preventive measures. Forty-three sheep and goat farms were included. Their locations were plotted and associated with T. gondii and N. caninum seroprevalence, then the distribution of farms’ prevalence was evaluated by spatial analysis. Significant clusters for both low and high prevalence were obtained, and a generalized linear model with ordinal logistic regression was implemented to verify if spatial clustering could be due to climate factors (temperature, rainfall, and their interaction). Clusters of high (80.0%) and low prevalence (28.12%) resulted for T. gondii seroprevalence in sheep farms. No significant clusters resulted for goat farms. Clusters of high (38.68%) and low prevalence (21.23%) resulted for N. caninum seroprevalence in sheep farms. One high-prevalence cluster (15.62%) resulted for goat farms. For goats, spatial analysis and analysis on climatic data showed the absence of environmental significant risk factors associated with T. gondii or N. caninum infection. On the contrary, for sheep, annual temperature, rainfall, and their association affected the risk of T. gondii and N. caninum infection. Particularly, high temperatures and abundant rainfalls were related to T. gondii seroprevalence, while low temperatures and scarce rainfalls were related to N. caninum seroprevalence.