Evidence for bovine besnoitiosis being endemic in Italy - first in vitro isolation of Besnoitia besnoiti from cattle born in Italy

Until 2009, bovine besnoitiosis had never been considered endemic in Italy and the only report on the disease in this country referred to animals imported from France shortly before. However, recently, an autochthonous outbreak of bovine besnoitiosis was reported in four herds located at the intersection of the borders between Emilia-Romagna, Toscana and Marche (Northern Apennine Mountains), which has led to an increased awareness concerning this disease. The present study describes a further outbreak of bovine besnoitiosis in Italy. The afflicted herd was a dairy herd with no evidence for contact with cattle from regions known to be endemic for bovine besnoitiosis. The farm investigation was initiated after a three-year old Holstein Friesian dairy cow with generalized thickening and lichenification of the skin was diagnosed with bovine besnoitiosis. The clinical diagnosis was confirmed by gross pathology, histopathology, serology and PCR. Bradyzoites released from tissue cysts obtained from the skin of this animal enabled the first in vitro isolation of Besnoitia besnoiti in Italy. This isolate was named Bb-Italy1. Sequencing of a 2118 bp spanning region including the complete internal transcribed spacer 1 and parts of the 18S and the 5.8S rRNA gene from DNA extracted from skin-derived zoites revealed a 99.9% identity to sequences known for other B. besnoiti isolated from cattle in Europe. Two GKO mice which had been inoculated intraperitoneally with bovine skin-derived bradyzoites became ill 7 days post inoculation. Parasitophorous vacuoles with multiplying zoites were observed in the cell culture inoculated with peritoneal fluids of these mice and a B. besnoiti infection in the mice and in the cell culture could be confirmed by real-time PCR. A serological investigation in the afflicted herd using immunoblots and an immunofluorescent antibody test (IFAT) revealed an overall herd seroprevalence of 9.7% (31/321), whereas within the female animals older than 2 years 17.0% (29/171) of the dams were tested positive. With one exception, an imported cow from Germany, all the seropositive animals were born in Italy. In connection with previously described autochthonous cases of bovine besnoitiosis the case described herein suggests that bovine besnoitiosis should be considered endemic in Italy.