Successive Outbreak of Tyzzer's Disease in Two Foals in the Same Area of Aomori Prefecture

Abstract

Two 25-day-old thoroughbred foals died of acute disease at the same area of Aomori Prefecture in April and May 2008. Histologically, there was multifocal necrosis in the liver of both foals. Warthin-Starry staining clearly showed long slender bacilli in the hepatocytes surrounding the necrotic foci. The bacilli were immunohistochemically positive for the polyclonal antibody against C. piliforme. Electron microscopic examination revealed the bacilli with peritrichous flagella in the hepatocytes. Real-time PCR analysis using primers specific to C. piliforme detected the genomes in both liver samples. On the basis of these findings, a diagnosis of Tyzzer's disease was produced. A serological survey using indirect immunofluorescence tests showed that the majority of mares in the region had the antibody to C. piliforme. These results suggest that C. piliforme has been widely distributed among horses in the region.