Initial Serological Examinations:

A routine sampling of 60 birds per house was carried out on September 21st (22 weeks, Ref. B.93.660). All were negative for antibodies to Mycoplasma gallisepticum and M. synoviae. HI antibodies titres for Newcastle Disease (GMT ranging from 6.6 to 7.1) and Infectious Bronchitis (GMT ranging from 7.7 to 8.8) were unremarkable for birds of this age. At the request of the local practitioner samples were also tested using agar gel precipitation for Avian Influenza, Type A. Twenty samples were tested from each house and all were found to be negative. All were negative in an Elisa test for Avian Rhinotracheitis (ART) with the exception of a single serum in house 3. This serum had an S/P ratio of 0.46 (below 0.25 are negative, 0.25 to .29 are suspect, and .3 or above are considered positive. On this basis it was considered that this might represent the start of sero-conversion and a second sample from house 3 was recommended. This was taken approximately 2 weeks later (October 5th - Ref. B.93.699). All 20 samples tested were negative in the ART Elisa test on this occasion. On this basis it was considered that ART infection was not the cause of the clinical problem.