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Entamoeba suis and Entamoeba polecki subtypes (ST) 1 and 3 have recently been implicated in disease outbreaks in pigs. However, the distributions of these parasites in Japan and the potential sources of infection on farms still remain unclear. Here, we examined a farm of fattening/growing pigs with abnormal feces in Kagoshima Prefecture, Japan, and found the presence of parasites in the farm environment. Examination of intestinal tissues from pigs presenting with ulcerative colitis revealed a large number of trophozoites that had invaded the lesions. We identified single and mixed infections of E. suis and E. polecki ST1 and ST3 in paraffin sections or fecal samples from affected pigs. Two subtypes of Entamoeba were identified using four primer sets by PCR and sequencing. The parasites were detected in moist soil samples obtained around the drinking water source or puddles, implicating transmission of cysts via contaminated soils. Additionally, we found evidence of Entamoeba spp. and coinfections in surveyed pigs without any diarrhea at two neighboring farms. Our results establish methods for successfully identification of parasites, including cases in which multiple infections are present.

An imported crossbred Angus beef steer aged eight to twelve months died suddenly on the eighth day of a quarantine period in Japan. Gross examination showed the peritoneum and mesentery consisted of numerous nodules of various sizes. Histological examination revealed chronic suppurative granulomatous peritonitis with eosinophilic rosettes surrounding colonies of Gram-negative bacilli. The bacteria isolated from the nodules were confirmed to be Actinobacillus lignieresii based on the results of 16S rRNA gene sequencing and immunohistochemistry. Antibiotic sensitivity testing showed that the isolate was resistant to penicillin. Thus, a diagnosis of atypical actinobacillosis caused by A. lignieresii was made.

Cystoisospora suis causes neonatal diarrhea in piglets worldwide. Although histopathological identification of this parasite is difficult owing to its similarity with other enteric coccidian parasites, including Eimeria spp., information regarding its molecular epidemiology in Japan is lacking. In this study, a 66-day-old post-weaned piglet reared in Shizuoka Prefecture, Japan, showed diarrhea and was examined using parasitological, histopathological, ultrastructural, and molecular methods to characterize the pathogens of the disease. Gross lesions were characterized by emaciation, thinning of the small intestinal wall, and lack of pulmonary collapse. Histopathologically, severe villous atrophy was detected in the jejunum, and Cystoisospora-like parasites were found in the cytoplasm of the epithelium. Interstitial pneumonia, purulent meningitis, pericarditis, and lymphatic abscesses were also noted. A microbiological and immunohistochemical analysis revealed that the piglet was also infected with porcine circovirus type 2, Escherichia coli serogroup O8, and group A rotavirus. Coccidial oocysts were recovered from diarrheic feces. PCR analysis targeting the rRNA internal transcribed spacer 1 (ITS1) and cytochrome c oxidase subunit 1 (COX1) genes of C. suis and sequencing revealed 100% similarity to those of C. suis in Kumamoto Prefecture, Japan. This study is the first report on the molecular identification of C. suis COX1 genes in Japan.Discipline: Animal health Additional key words: cytochrome c oxidase subunit 1, Escherichia coli serogroup O8, group A rotavirus, internal transcribed spacer 1, porcine circovirus type 2

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