An outbreak of systemic histomoniasis in 9-to-11-wk-old meat-type male turkeys associated with high mortality is reported. Clinical signs in turkeys included anorexia, depression, diarrhea, loss of weight, and increased mortality between 7 and 13 wk of age. Seven-week cumulative mortality in the turkeys of affected houses ranged from 24% in one to 68% in the other compared with 1.3% of turkeys in the house not affected by histomoniasis. Necropsy of the turkeys revealed enlargement of the livers, most of which had numerous pale white nodules ranging in size from 0.3 to 1.5 cm in diameter. Cecal walls were severely thickened, the lumens were distended with caseous cores, and the mucosa was ulcerated. The bursa of Fabricius in four birds was enlarged and contained pale yellow exudate in their lumens. The kidneys, pancreas, and spleens in a few birds had pale or yellow foci. Microscopically, there were multifocal necrosis and granulomatous inflammation in the liver, ceca, peritoneum, bursa of Fabricius, kidneys, lungs, pancreas, proventriculus, and in spleens associated with histomonads. Electron microscopy also confirmed the presence of histomonads in the liver and ceca. This is the first report of naturally occurring systemic histomoniasis in turkeys affecting the bursa of Fabricius, kidneys, lungs, pancreas, and proventriculus.
Systemic Mycoplasma synoviae infection in 47-day-old broiler chickens with septicaemic lesions and increased carcass condemnation rate is reported. The clinical history included respiratory signs and an enlarged keel bursa. Condemnations at the processing plant were due to airsacculitis and keel bursitis. Involvement of several organs, including the keel bursa, liver, spleen, brain, choroid of the eye, nerves and skeletal muscle associated with vasculitis, and the isolation of M. synoviae from the liver and keel bursa are only occasionally seen in field cases. Random amplified polymorphic DNA analysis of the M. synoviae isolated from the broiler chickens in this study had a different pattern when compared with the reference M. synoviae strains, WVU-1853, MS-H and F10-2AS, and another M. synoviae isolated from broiler breeders from the same company, but had a similar DNA pattern to an M. synoviae isolated from broiler chickens and turkeys owned by the same company. This finding suggests a horizontally acquired infection rather than vertical transmission.
On the basis of the data from the California Animal Health and Food Safety Laboratory System, 1444 infectious bronchitis (IB) cases were diagnosed between 1997 and 2012. Epidemiologic analyses demonstrated two major IB virus (IBV) outbreak peaks, affecting mainly 35-to-49-day-old broiler chickens. California variant 1737 (CA1737) and California variant 1999 (Cal 99) IBV types were the most prevalent genotypes during the analyzed period. To further understand the increased prevalence of these genotypes, we assessed and compared the variability of the S1 gene hypervariable region of CA1737 and Cal 99 with the variability of IBV strains belonging to the Massachusetts 41 (M41) and Arkansas (Ark) types during serial passages in embryonated chicken eggs. On the basis of the S1 nonsynonymous changes, seven different subpopulations were detected in M41. However, the predominant population of the field strain M41 before passages continued to be predominant throughout the experiment. In contrast, Ark passaging resulted in the detection of 13 different subpopulations, and the field sequence became extinct after the first passage. In IBV Cal 99, eight different subpopulations were detected; one of these became predominant after the second passage. In CA1737, 10 different subpopulations were detected. The field strain major sequence was not detected after the first passage but reappeared after the second passage and remained at low levels throughout the experiment. Compared with M41 and Ark, Cal 99 and CA1737 showed intermediate variability.
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