Incidence and Economic Impact of Reovirus in the Poultry Industries in the United States.

Avian reoviruses have sole or partial responsibility for a wide range of conditions that are of economic concern to the poultry industries in the United States. It is difficult, however, to determine the exact cost of reoviral-induced disease to this industry for several reasons. Avian reoviruses are ubiquitous in commercial poultry operations, but vary greatly in their ability to cause disease. Many reovirus isolates are not pathogenic, and this contributes to the difficulty in determining their role in production losses or whether they are merely coincidental findings of little or no importance. Results of infection with this virus can be difficult to measure in a commercial setting, aside from morbidity, mortality, or loss of finished product in a processing plant due to condemnation or trim. The fact that there is a relatively high morbidity rate, and at the same time a low mortality rate, makes it extremely difficult to accurately estimate the economic impact of infection with this virus. Variations in the pathogenicity of the virus, the extent of infection within a flock, the blending of progeny from different breeder source flocks into a broiler house, and the lack of separation of infected birds from uninfected birds at processing makes evaluation of economic variables, such as feed conversion and weight gain, very difficult to ascertain. The broiler and turkey industries have been surveyed on the importance of this virus in their respective operations and the results will be consolidated here to consider the economic impact to the poultry industries in the United States.