Sampling quality in bovine spongiform encephalopathy routine monitoring in Belgium - short communication.

The bovine spongiform encephalopathy (BSE) epidemics have led to active surveillance in Europe. Detection methods are focused on the obex, where prions first accumulate in the central nervous system (CNS). Sampling is made with a calibrated syringe (from Bio-Rad or Idexx) that must sample a target area in the obex area. This study checked the precision of the sampling in Belgian routine laboratories in 2010 and 2011 (analysed obex: N = 184 and N = 368). For that purpose, the obex was divided into 130 identical square zones with 50 in the target area. The success of sampling the target area was identical when comparing the years (72.8%). The different laboratories obtained similar results. However, in 2011, one of the four laboratories had a lower number of zones inside the target area than the best laboratory. As a conclusion, obex sampling in Belgium is adequate, provided the technicians are well trained. This is especially true when confronted with atypical BSE, for which the obex is not the primary region of prion accumulation.