Prevalence and Differentiation of Diseases in Maryland Backyard Flocks

Several epidemiologic surveillance studies have implicated backyard flocks as a reservoir for poultry diseases; however, much debate still exists over the risk these small flocks pose. To evaluate this concern, the prevalence of Newcastle disease (ND), infectious laryngotracheitis (ILT), Mycoplasma gallisepticum (MG), and Salmonella was determined in 39 Maryland backyard flocks. Serum, tracheal, and cloacal swabs were randomly collected from 262 birds throughout nine counties in Maryland. Through PCR and ELISA analysis, disease prevalence and seroprevalence were determined in flocks, respectively, for the following: ND (0%, 23%); ILT (26%, 77%); MG (3%, 13%); and Salmonella (0%, not done). Vaccine status could not be accurately confirmed. Premise positives were further differentiated and identified by partial nucleotide sequencing. Screening of the 10 ILT premise positives showed that most were live attenuated vaccines: eight matched a tissue culture origin vaccine, one matched a chicken embryo origin (CEO) vaccine, and one was CEO related. The single MG-positive flock, also positive for the CEO-related sequence, was identified as the infectious S6 strain. The prevalence rates for these economically important poultry diseases ranged from none to relatively low, with the vast majority of sampled flocks presenting no clinical signs. Prevalencia y diferenciación de las enfermedades en aves de traspatio de Maryland. Varios estudios de vigilancia epidemiológica han implicado a las parvadas de traspatio como reservorio de enfermedades para la avicultura, sin embargo, aún existe un gran debate sobre el riesgo que ofrecen estas pequeñas parvadas. Para evaluar esta preocupación, se determinó la prevalencia de la enfermedad de Newcastle (ND), de la laringotraqueitis infecciosa (ILT), de Mycoplasma gallisepticum (MG) y de Salmonella en 39 parvadas de traspatio en el estado de Maryland. Se recolectaron muestras de suero, hisopos de tráquea y cloaca de manera aleatoria de 262 aves a lo largo de nueve condados en Maryland. A través del análisis de PCR y de ELISA, se determinaron la prevalencia y la seroprevalencia, respectivamente de las enfermedades en las parvadas, y resultaron como a continuación se describe: enfermedad de Newcastle (0%, 23%); laringotraqueítis infecciosa (26%, 77%); M. gallisepticum (3%, 13%); y Salmonella (0%, no llevada a cabo). El estado de las vacunaciones no se pudo confirmar con precisión. Las parvadas positivas se analizaron más detalladament