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Infectious Bronchitis in Domestic Chickens

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Title: Infectious Bronchitis in Domestic Chickens
Author: Chute, Harold, L.
Abstract: Infectious bronchitis has been a respiratory disease problem in domestic chickens (Gallus domesticus) in United States since its discovery in 1931. The disease is also widespread in Canada. Witter and Reed reported in 1939 that "colds" in chickens were prevalent is some areas of the State of Maine. In 1944 Van Roekel, Department of Veterinary Science, University of Massachusetts found neutralizing antibodies in the blood of infected chickens. It was assumed up to time that the outbreaks were sporadic and local in nature. During the fall and winter of 1944-45 the disease constituted the greatest disease hazard of laying flocks. A survey was made by questionnaire in March, 1945 and from 734 replies it was found that I8 per cent reported respiratory disease outbreaks. Ninety-eight of these outbreaks were reported in laying birds of which 57 per cent indicated a marked decrease in egg production. At a special meeting held in Hallowell, Maine, April 6, 1945, a program of control was evolved and approved by directors of the Maine Poultry improvement Association. After approval by the State department of Agriculture this was put into immediate effect. Twenty-two flocks, representing 90, 394 birds, were enrolled, in the program in 1945. The number of flocks tripled the next year and has increased markedly during succeeding years. In 1948-49, 325 flocks comprising 657, 930 birds and in 1949-50, 897 flocks comprising 1, 586, 647 birds were inoculated. The program was based on the request of poultrymen, who had previously had respiratory problems in their birds, to obtain from the University of Maine the infectious bronchitis virus to inoculate their flocks. A fieldsman was sent to the farm when the birds were 6-12 weeks of age and five per cent of the birds were swabbed in the trachea with a suspension of Mucosal scrapings from an infected trachea diluted in saline. In the beginning the pathogenic bronchitis virus was propagated in live birds. Early in 1950 the field strain of the infectious bronchitis virus was propagated in chicken embryos and the infected allantoic fluid was used for a vaccine. Newcastle disease had been discovered In Maine In 1947 and an active wing web vaccination program for this disease was soon put into effect. In spite of vaccination for infectious bronchitis and Newcastle disease, respiratory infections continued. Many probIems such as the duration and degree of immunity in vaccinated flocks were posed. The objective of this study was to investigate some of the respiratory disease problems and to improve the vaccine. These studies have been conducted with the same strain of infectious bronchitis virus over a five-year period, 1950- 1955.
Description: A thesis presented for the degree of Doctor of Veterinary Science. The University of Toronto. 1955
Date: 1955
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