From Markus Moser and Bruno Oesch, Prionics
The article on BSE in Switzerland quoted one of us as saying that “1800
subclinical cases may have ended up on the table” last year
(This Week, 13 June, p 4).
The full quote was: “If you assume the same incidence in the general
population, 1800 subclinical cases may have ended up on the table. But the
actual number of subclinical BSE cases present in the current population really
has to be determined.” The general incidence of subclinical BSE in Switzerland
may be less than in the culled herds tested so far.
The results presented in the article were also not represented entirely
correctly. Out of 1761 animals examined, four animals tested positive by both
immunohistochemistry and the Prionics immunoblotting test. Three of these
animals tested positive for spongiform change. In addition, two further animals
tested positive by immunohistochemistry alone and another two by the Prionics
test alone. The differences between the test results may lie in the techniques
used or may simply represent the fact that the two methods cannot be performed
on the same tissue sample.
In conclusion, three animals each tested positive by three different methods
and one by two methods, while four animals were positive by only one method.
Zürich
