Comparison of histopathology to the direct immunofluorescent antibody test for the diagnosis of infectious laryngotracheitis in chickens.

Histopathology and direct immunofluorescent antibody (DIFA) tests were compared for diagnoses of infectious laryngotracheitis (ILT) in 144 cases of spontaneous respiratory disease in chickens presented to the Georgia Poultry Laboratory during 1988. For the 48 cases in which ILT was diagnosed, correct histologic diagnoses were made 100% (48/48) of the time and correct DIFA diagnoses were made 96% (46/48) of the time. For the 96 cases in which ILT was not diagnosed, correct histologic and DIFA diagnoses were made in every case. A Kappa test showed that DIFA was as effective as histopathology for the diagnosis of ILT in chickens (P = 0.0). It was concluded that increased use of DIFA could be instrumental in the abatement of ILT in chickens.