EPIDEMIOLOGY OF SELECTED PROTOZOAN INFECTIONS IN DOMESTIC RUMINANTS

Among Apicomplexa, particularly three protozoa infecting domestic ruminants (i.e. Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti) were selected in the current studies. All of them are nowadays considered (re-) emerging and under-reported in Europe but they are proven to have important consequences on public health and food security, in addition to animal welfare and health. Moreover, an economical aspect concerning zootechnical activities is to be highlighted: T. gondii and N. caninum are considered major infective cause of reproductive failure in small ruminants, with huge economic impact, although few data are available mostly on neosporosis in small ruminants. Similarly, bovine besnoitiosis is responsible of economic losses in affected herds and epidemiological surveys are necessary to monitor the presence of B. besnoiti in Europe. Therefore, the aim of my doctoral project was to investigate on the selected protozoan infections in small ruminants and cattle, following different research lines. A serosurvey was carried out to update epidemiological data on T. gondii and N. caninum infections in small ruminants bred in Northern Italy. High seroprevalence values were registered for both protozoa at individual and farm level, consistent to those registered in previous survey carried out in European countries. Further, spatial analysis was performed in order to determine geographical and climatic features able to facilitate the maintenance of T. gondii and N. caninum infections within the study area. For T. gondii infection in goats an area of high risk of infection was identified and climatic variables, such as mild temperature and rainfall, resulted predictors of infection. Geospatial analysis and analysis on climatic data revealed useful tools for the identification of clusters of infection, although data obtained should be always interpreted considering individuals and herds factors. A deeper investigation on T. gondii infection in small ruminants’ foodstuff was planned. Milk and meat were selected as products potentially posing a risk for consumers. Firstly, a commercial ELISA was validated to analyze goats’ milk sample. In a “case study” caprine farm naturally infected by T. gondii, variation in antibodies anti-T. gondii both in serum and milk during lactation was analyzed. Different curves of antibodies level in sera and milk were observed. Finally, two epidemiological surveys were carried out on ovine and caprine products: antibodies anti-T. gondii were detected in caprine bulk tank milk and in meat juice obtained by slaughtered goats and sheep, registering quite high prevalence values. Finally, an epidemiological survey on bovine besnoitiosis was performed on dairy and beef cattle bred in northern Italy (Lombardy and Piedmont), Liguria region and Sardinia Island. Only five independent foci of infection were registered in Lombardy region. However, when a subsequent in-depth analysis was performed in a seropositive farm applying different diagnostic tools (serology, histology and immunohistochemistry), high intra-herd prevalence and several clinical cases were recorded. Concluding, high values of Toxoplasma gondii and Neospora caninum seroprevalence were registered in small ruminants in Northern Italy; geospatial analysis revealed a useful tool for an inclusive comprehension of predictors involved in the infections. T. gondii infection deserves a major attention considering the sanitary risk posed by caprine and ovine foodstuff. Alternatively to classic serological methods, analysis on individual and tank bulk milk and on meat juice samples were confirmed a valid tool for a fast and affordable screening of T. gondii infection in small ruminants. Finally, an important contribution to the epidemiology of an emerging disease as bovine besnoitiosis was given, with the update of epidemiological data and the deeper investigation on an infected farm, confirming the necessity to plan monitoring controls.