Explanation PCR results


The results of the PCR-test are presented with:

  • “+” : The virus is detected.
  • “-“ : The virus is not
  • “+/-“: The virus is detected, but it is not clear whether this is a (recent) infection or external contamination. This result counts as negative in the calculation of the percentage.
  • INV: During the execution of the test, it turned out that the material was not suitable for testing. This is usually due to aging of the material.


The mentioned percentage is based on a test of 10 x 24 pieces.


Cq-values are given only for PlAMV and TVX. The results of other viruses are mostly clear virus free or virus infected. That is why no Cq-values are given for these viruses.

Limits Cq-value PlAMV

Cq 38-40; result “-“.

Cq 33-37; result “+/-“.

Cq 0-32; result “+“.

Limits Cq-value TVX

Cq 35-40; result “-“.

Cq 0-34; result “+“.


Interpretation of the result of a contact or water sample

The results are presented with a Cq-value. The lower the value, the more virus particles have been detected in the sample. A value of 40 indicates that no virus has been detected in the sample. A negative result of a virus test on a contact or water sample is no guarantee of the absence of virus.


A negative outcome of a virus test of the (sub) sample does not necessarily guarantee the absence of virus in the lot.


Decisionmaking-model PCR PlAMV and TVX