Circulation of Immunosuppressive Viruses and Avian Encephalomyelitis Virus in Backyard Chicken Flocks

Abstract

The objective of this study was to evaluate the circulation of Chicken Anemia Virus (CAV), Infectious Bursal Disease Virus (IBDV), Avian Reovirus (ARV) and Avian Encephalomyelitis virus (AEV) in properties of backyard chickens and carry out an epidemiological analysis. We evaluated 200 samples of chickens from 19 backyard chicken property. Only one property (P10) did not present serological titers for the diseases evaluated. This property is close to industrial farms as well as the other properties, however, P10 remained a few years without the breeding of chicks and these were the first poultry to be housed on site. This reinforces the importance of the fallow period for poultry production. The prevalence of virus-seroreactive birds was 78% (156/200), 64.5% (129/200), 78% (156/200), 78% (156/200) for CAV, IBDV, ARV and, EA, respectively. All the free-range farms studied are within a radius of 500 meters to 6 Km away from some establishments of industrial poultry. There was a correlation between serological titers for CAV and the frequency of disease in poultry (r = 0.6178). In places where birds are frequently sick, 30.76% reported that the disease occurs in chicks, 30.76% in broilers, 23.07% in broiler chickens and 7.69% in birds of all ages. Birds get sick more often in the summer period. The owners reported that the most common signs of disease were respiratory signs (snoring and nasal discharge) (46.15%), diarrhea (30.76%), and paralysis of wings and/or paws (38.46%). There was a correlation between the presence of untreated water in the property and serological titers for ARV (r = 0.5576). This report draws attention not only to high serological prevalence for the viruses studied but also important epidemiological aspects of backyard chicken diseases that may indirectly influence the industrial production.