BVD all Island maps 02/04/2019



Updated maps illustrating the spatial patterns of Bovine Viral Diarrhoea (BVD) infection have been released through AHWNI.  These maps show that, while there are encouraging signs that the number of living BVD positive cattle are falling in NI, some pockets of retained Persistently Infected (PI) animals have remained unchanged since the previous production of the maps in October 2018.

The maps, which use anonymised data and fixed sized hexagonal units to represent disease densities, were produced by the Centre for Veterinary Epidemiology and Risk Analysis (CVERA), University College Dublin, in collaboration with Animal Health Ireland (AHI) and DAERA.  They are based on statistics covering up to the end of January 2019. 

Progress may be seen in the decrease in the number of living PIs (Map 2) compared to the previous mapping exercise, as the number of hexagons with the highest density of PIs alive has approximately halved in a six month period.  Just over three years into the compulsory programme, the NI cattle population has experienced a 35% decrease in rolling annual animal prevalence levels and a 39% reduction in rolling annual herd prevalence of BVD. 

Localised foci of disease at the animal level, particularly in East Tyrone, Armagh and West Down, suggest that in these areas herd owners should be very aware of BVD risks to their herds.  In some hexagons, the higher densities of living PIs seen are due to a small number of farms having had several PIs disclosed on testing.  BVD PIs should be disposed of at the earliest opportunity, so that BVD can be stamped out at the herd level and ultimately from the NI cattle population.

Map 3 displays the location of retained PIs, that is, those PIs that are still alive on farm more than 35 days after a positive result was released.  The map illustrates the extent of PI retention, and therefore the risks that exist for other herd keepers.  At 1st April 2019, there were 490 PIs retained on farm for more than 5 weeks, in 317 herds.  Failure to dispose of PI animals is considered to be the most significant obstacle hindering the progress of the scheme.

Overall, the maps show the all-island picture of BVD infection and allow comparison of progress in tackling the disease.  The AHI-run programme in the RoI has made remarkable progress; financial supports, herd restrictions and the issue of biosecurity notifications have been credited with a large measure of the success seen. 

Map 1                                                                                                                                           

Map 2

Map 3