First Isolation of Salmonella enterica subsp. enterica serovar Cerro from Cattle in Hokkaido, Japan

Abstract

In 2024, Salmonella enterica subsp. enterica serovar Cerro (S. Cerro) was isolated from three asymptomatic calves during screening conducted upon arrival at three farms in the Tokachi region of Hokkaido, Japan. These cases represent the first documented isolation of S. Cerro in Hokkaido. Pulsed-field gel electrophoresis (PFGE) analysis revealed that two isolates displayed the same pattern, while the third was genetically related, suggesting the potential spread of similar strains across different farms. Although increasingly reported in cattle in the United States, this serovar remains rare in Japan. Notably, the infected calves showed no clinical symptoms. However, the movement of asymptomatic carrier animals poses the risk of broader dissemination through shared transport or collection facilities. Prompt countermeasures were implemented at each farm, including the temporary isolation of the animals and repeated fecal testing until negative results were confirmed. These findings highlight the epidemiological importance of detecting salmonella serovars with potential zoonotic relevance, even in the absence of symptoms. Early identification and management of asymptomatic carriers is critical for preventing further transmission. This case underscores the importance of implementing routine salmonella screening upon the arrival of animals and the maintenance of temporary isolation protocols for newly introduced animals to reduce the risk of the spread of disease. Continued surveillance is essential to assess the prevalence and distribution of S. Cerro in Japan's cattle population.