We started with 5 hens and 1 rooster. Only symptom was walking with rump in the air and irregular laying. Your State Vet might come and take the hen to a state lab. A hen past 6-8 months and not laying is a clue that reproductory system is either not normal or infected.
Sudden death is another.
Would surely try to find out. A blood test on the other birds would quickly diagnose, if pullorum. A call to your State Vet would doubtless bring someone authorized to test. This is a private posting area. A valid username and password combination is required to post messages to this discussion.