Abstract Book of EAVLD2012 - eavld congress 2012

S1 - P - 28
SPECIFIED RISK MATERIAL REMOVAL PRACTICES:
CAN WE REDUCE THE BSE HAZARD TO HUMAN HEALTH?
D. Pitardi 1 , D. Meloni 1 , C. Maurella 1 , D. Di Vietro 1 , L. Nocilla 1 , A. Piscopo 2 , E. Pavoletti 3 , M. Negro 4 , M. Caramelli 1 ,
E. Bozzetta 1 .
1 Istituto Zooprofilattico Sperimentale del Piemonte Liguria e Valle d’Aosta, Via Bologna 148, 10154, Torino, Italy.
2 Azienda Sanitaria Provinciale 1AG, Viale della Vittoria 321, 92100, Agrigento, Italy.
3 Azienda Sanitaria Locale VC, Via Benadir 35, 13100, Vercelli, Italy.
4 Azienda Sanitaria Locale CN1, Corso Francia 12, 12100, Cuneo, Italy.
BSE; vCJD; Spinal cord; SRM Contamination; Alternative slaughter practices.
Introduction
Following the bovine spongiform encephalopathy (BSE)
epidemics across Europe in the early 1990s, the removal of
designated BSE specified risk material (SRM) became
mandatory to minimize the risk to consumers of exposure to the
infectious agent. Despite this preventive measure, crosscontamination
of edible meat with SRM can occur during
conventional slaughter (1-4).
Currently, there are no markers that can identify the presence of
SRM in meat as a whole. Nevertheless, some assays are able to
detect traces of CNS, hence this parameter is officially taken as
indicative of SRM contamination.
In this two-stage study, we carried out a survey to estimate the
prevalence of carcass contamination at two slaughterhouses, one
large and the other medium-sized; we then compared three
different methods (conventional vs. suction vs. water-jet) for
spinal cord removal employed at the large slaughterhouse to
assess their performance in preventing the spread of CNT over
the carcass.
Materials & methods
Prevalence of CNS contamination
The prevalence of CNS contamination by the conventional
technique was estimated from a total of 216 carcasses from a
large slaughterhouse and 196 from a medium-sized one. In both
abattoirs the carcasses were split with a hand-guided belt-type
saw and the spinal cord cut along its length was removed from
each side of the carcass. Sampling was performed immediately
after spinal cord removal.
Alternative techniques
Two alternative spinal cord removal techniques were compared
to the conventional method. In both techniques, the SRM is
extracted before the carcass is split (by suction or by water-jet).
Comparative study
The estimated sample size (50 carcasses) was sampled for each
SRM removal method: conventional; suction; and water-jet. The
specimens were withdrawn immediately after carcass splitting.
Sample collection and preparation
Bovine older than 12 months were included in the study. Samples
were collected from a defined area on the medial surface of each
half of the split carcass. The area was selected and marked off
on the paravertebral muscles.
Testing activity
A commercially available ELISA kit (Ridascreen® Risk Material
10/5, R-Biopharm), which detects GFAP as a marker for CNS,
was used to analyze the samples. In order to facilitate application
of the test for screening purposes, in previous studies we
validated its qualitative use by plotting an ROC curve to set a
useful cut-off value (2).
Results
Using a qualitative approach, samples were defined as positive if
CNS tissue was detected at a concentration ≥0.049% (2).
Samples tested positive in 130/216 carcasses (60.2%, 95% CI
53.3-66.8) from the large slaughterhouse and in 152/196 (77.6%,
95% CI, 71-83.2) of those from the medium-sized one (Table I).
The conventional slaughter technique was associated with an
overall prevalence of CNS contamination of 68.4% (95% CI, 53 -
83).
The comparative study showed a CNS contamination of 62%
(95% CI, 47.2-75.3) associated with the conventional technique,
60% (95% CI, 45.2-73.6) with the suction technique, and 36%
(95% CI, 22.9-50.8) with the water-jet system (Table II). The
difference among the three methods appeared to be significant
(P=0.0047).
Table I: Conventional method - positive samples stratified
according to contamination level and type of abattoir.
Large abattoir Medium abattoir
CNS contamination positive samples positive samples
(%)
(%)
Low ( ≥ 0.049 and