Enzootic bovine leukosis: Report of eradication and surveillance measures in Italy over an 8-year period (2005–2012)

Abstract

Bovine leukaemia virus (BLV) is associated with enzootic bovine leukosis (EBL). BLV causes malignant lymphoma and lymphosarcoma; however, most BLV infections remain clinically silent in an aleukaemic state. EBL is a notifiable disease, and official control measures include screening or monitoring, precautions at borders, control of movement inside the country, and stamping out.The objective of this study was to evaluate EBL eradication and surveillance measures in Italy from 2005 to 2012. One-hundred twenty-three outbreaks were recorded (1 January 2006 to 31 December 2012) in the National Veterinary Information System (SIMAN) on 7 November 2013. Of these, 101 had occurred in southern Italy. An outbreak usually lasted for a few days, but sometimes lasted for weeks. Some areas were subjected to normal eradication measures, whereas others were subjected to additional eradication measures as a consequence of persisting EBL outbreaks. During the study period, we noted an overall annual decrease from 0.21% in 2005 to 0.08% in 2012 in the herd prevalence rate, from 0.06% in 2005 to 0.04% in 2012 in the herd incidence rate, and from 0.027% in 2005 to 0.015% in 2012 in the animal prevalence rate. Regions officially recognised as EBL-free areas were found to have their own surveillance plans. Differences in their surveillance plans include the type of sample (serum, milk, or both), age at which the animals must be tested (12 or 24 months), and test frequency of herds (annually or every 2, 3, 4, 5, or 6 years). The eradication programme for EBL is difficult to implement in some Italian areas because of several factors such as incomplete herd registry, geographical location and socio-economic conditions of the region.