  We consider a model for an infectious disease in the onset of an outbreak. We
introduce contact tracing incorporating a tracing delay. The effect of
randomness in the delay and the effect of the length of this delay in
comparison to the infectious period of the disease respectively to a latency
period on the effect of tracing, given e.g. by the change of the reproduction
number, is analyzed. We focus particularly on the effect of randomness in the
tracing delay.
