Cytauxzoon sp.: un protozoo emergente nel gatto

Cytauxzoon felis (C. felis) is a protozoan responsible for cytauxzoonosis, a tickborne infection which affects wild and domestic felids that has been firstly described and studied in the United States. Cytauxzoonosis is an acute, severe and fatal disease in most domestic cats, even if rarely cases of surviving to the infection have been reported. On the other hand, wild affected cats more often had a persistent parasitemia without clinical signs and rarely occured in acute and fatal disease. Recently sporadic infections caused by Cytauxzoon sp. have been reported in wild and domestic cats in Mongolia, Spain and France. No further information about this pathogen is available and it has never been reported in Italy. The aims of this work were: 1) to identify the presence of Cytauxzoon sp. in Italy and 2) to increase knowledge about epidemiology, pathogenesis, ways of transmission, infection carriers and clinico-pathological findings of this infection in domestic cats. The first Cytauxzoon sp. focus in Europe is been identified and described in Trieste (Northeastern Italy) (chapter one). Then it was organized an epidemiological study, involving cats randomly selected (healthy, sick , owned, stray) among patients of some veterinary clinics located in three areas of the Italian territory (Northeast , Central and South). Blood samples for laboratory tests and information on medical history, lifestyle, recent or remote contact with fleas and/or ticks, ectoparasites prophylaxis and clinical signs were collected for each cats (chapter fourth). Moreover, it was evaluated the effect of a therapeutic protocol in two infected cats (chapter two). Ectoparasites (ticks and/or fleas) collected at the time of the clinical evaluation and uterus and fetus, if available, of pregnant females were taken from colony cats living on the Trieste’s focus in order to investigate the Cytauxzoon sp. way of transmission. The cats involved in the study were captured as part of the campaigns of sterilization for birth control (chapter three). Finally, it was made a statistical analysis of all available data comparing infected and not infected subjects (chapter four). The diagnosis of Cytauxzoon sp. infection was made by identification of piroplasms in the blood smear and/or by 18S rRNA gene PCR analysis and sequencing. In the present work Cytauxzoon sp. infection has been described for the first time in Italy with a prevalence of 23% in the focus of Trieste (Northeastern Italy) and of 2.59% in the overall Italian territory. The sequences obtained from infected cats showed an homology of 93% with C. felis and 99% with Cytauxzoon sp. described in Mongol, Spanish and French wild and domestic felids. The majority of the infected domestic cats were young (< 15 mounths), free or semi-free ranging, persistently parasitemic, asymptomatic and not anemic. Rarely cats died or were euthanized after showing variuos clinical signs while in most cases the infection seemed to be chronic and subclinical. In a pregnant infected cat, tissues inclusions compatible with schizonts of Cytauxzoon sp. were observed inside machrophages in the placenta and fetal muscle tissue. Based on this finding it was suspected that this infection could be vertically transmitted. In addition, the PCR analysis performed on fleas (Ctenocephalides felis felis) and ticks (Ixodes ricinus and Rhipicephalus sanguineus) collected from some cats living in the colonies of Trieste were all negative. Also vectors taken from infected cats resulted negative to PCR analysis. Finally, a therapeutic protocol based on Doxicicline and Imidocarb dipropionate has been applied in two infected kittens. At the end of the therapy in one case blood smear evaluation for piroplasms and PCR analysis was negative throughout the follow up period (175 days). In the second cat the parasitemia is not resolved but treatment was not completely performed because the owner has spontaneously suspended administration of Doxicicline after a week.