From August to November 1987, 105 cattle in Kagoshima Pref. became affected with Ibaraki disease; major symptoms included foamy hygrostomia, water regurgitation, laryngopharyngeal paralysis, and fever. Sixteen of the cattle died. Virological and pathological examinations were conducted in four of these 16 cases, and the following findings were obtained:
1) Isolation of the pathogenic virus was attempted in two of the cows, and Ibaraki virus was detected in both cases.
2) The dead cows showed neutralizing antibody titer of 1: 4 to 1: 2048 or more. Of 14 cows which had been in the same herd with these cows and apparently looked healthy, 6 cows showed positive reaction against the antigen.
3) Macroscopically, there appeared esophageal chalasia and dilation, hemorrhage and white spotting of esophageal muscle, hemorrhage in pharyngeal muscle, hepatization and emphysema of the lungs, foamy fluid retention in bronchus, and pus-like pituita in the nasal cavity.
4) Histologically, hyaline degeneration, lysis, and disappearance of myocytes, nuclear swelling in myocytes, and hyperplasia of interstitial connective tissue were evident in esophageal and pharyngeal musculature. Serious calcification was observed in 2 cases. The lung developed serious foreign body pneumonia, and oral and esophageal glands were swollen and destroyed. In one case, atrophy and necrosis of cardiacmuscular cells and mild hyperplasia of interstitial connective tissue were observed.
5) The cause of death was considered to be acute aspiration pneumonia induced by dysphagia due to laryngopharyngeal and esophageal paralysis.
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