4. Discussion
Our observation, PCR detection of A. astaci DNA in tissues, uropods
and leg joints, of overtly healthy wild noble crayfish, indicates that
these crayfish can be chronically infected by subclinical A. astaci.
Even when A. astaci DNA was detected at relatively high prevalence
in our sample, no increased mortality was evident in the wild population,
nor amongst our experimental crayfish housed under supposedly
stressful cage conditions.
Interestingly, so far A. astaci DNA has not been detected in crayfish
populations downstream of the Lake Mikitänjärvi population in the
watershed system in which it was detected by PCR. The low level infection
detected could be the reason for Lake Mikitänjärvi noble crayfish
showing no gross symptoms of infection. These crayfish could act
as latent carriers, since A. astaci was clearly detected by TaqMan®
MGB PCR, similarly to what has been suggested for signal crayfish