Background Escherichia coli is an important cause of diarrhea in calves and its diarrheagenic properties are related to presence of certain virulence genes. In this study, the prevalence of virulence genes F5 , F17 , F41 , sta , stx1 , stx2 , eae , and saa in E. coli isolated from pre-weaned calves presenting with (n= 329) or without diarrhea (n= 360) was explored using multiplex polymerase chain reaction. We also evaluated the association between detection of E. coli and the presence of diarrhea. Results Escherichia coli was detected in 56.3% (388/689) of the fecal samples and showed the highest prevalence (66.5%) in 21–40-day-old calves and the lowest (46.3%) among those that were 1–20 days old. The prevalence of the enterotoxigenic E. coli (ETEC) and Shiga toxin-producing E. coli (STEC) pathotypes was detected in 73.9% and 15.9%, respectively. The results showed no association between diarrhea and the presence of E. coli in general, ETEC or STEC. The F17 gene was the most frequently detected virulence factor in E. coli of calves of all ages regardless of diarrhea. Interestingly, the results show that the calves aged 41–60 days with F17 -positive E. coli are at a higher risk for production of Shiga toxin ( Stx1 ; 95% confidence intervals: 1.86–31.95; P = 0.005) compared to calves aged 1–20 days; no association between this finding and diarrhea was observed among the calves of this age group. Moreover, the virulence genes associated with the ETEC and STEC strains were not significantly associated with pathogenicity in this study cohort. Conclusions These results suggest that while the incidence of E. coli is age-related, there was no relationship linking E. coli virulence genes to calf age and diarrhea. Furthermore, the present study demonstrated that detection of E. coli strains either with or without virulence factors was not associated with diarrhea in pre-weaned calves.

Background: Enterocytozoon bieneusi is the most common microsporidian species infecting humans and various animals worldwide. To date, there has been limited information on the prevalence of infection and genotypes of E. bieneusi in cattle in the Republic of Korea. Therefore, this study investigated the prevalence and genotypes of E. bieneusi circulating in pre-weaned Korean native calves and determined the age pattern of E. bieneusi infection and the relationship between E. bieneusi infection and diarrhea. Methods: The prevalence of E. bieneusi infection in pre-weaned Korean native calves was screened by polymerase chain reaction. PCR-positive products were sequenced to determine the genotype of E. bieneusi. A Chi-square analysis was used to compare the association between diarrhea and the infection rate of E. bieneusi in each age range or for all ages. Results: PCR and sequencing analysis revealed an overall prevalence (16.9%, 53/314) of E. bieneusi in pre-weaned calves. The prevalence of E. bieneusi was highest in September (36.2%), followed by March (28.3%). Enterocytozoon bieneusi infection was associated with diarrhea in calves (χ 2 = 5.82, P = 0.016). Our results also indicated that E. bieneusi infection was significantly associated with calf age (χ 2 = 11.61, P = 0.003), and the prevalence of E. bieneusi infection was significantly higher in calves aged 21-40 days-old (odds ratio: 2.90, 95% confidence interval: 1.54-5.45; P = 0.001) than in those aged 1-20 days-old. Interestingly, the association between E. bieneusi infection and diarrhea was observed only in calves aged 1-20 days-old (χ 2 = 5.82, P = 0.010). We identified three known genotypes, BEB4 (n = 12), BEB8 (n = 21) and J (n = 16), and three novel genotypes, BEB8-like (n = 21), KCALF1 (n = 1) and KCALF2 (n = 1). The genotype BEB8 was the most prevalent among all age groups. All genotypes identified in this study exhibited zoonotic potential. Conclusions: To our knowledge, this is the first report of the genotype BEB4 in pre-weaned Korean native calves. Zoonotic E. bieneusi infection was prevalent in pre-weaned calves, indicating that cattle may play an important role as a reservoir host for E. bieneusi transmission to humans.

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BackgroundEnterocytozoon bieneusi is the most common microsporidian species that can infect humans and various animals worldwide. To date, there has been limited information on the prevalence and genotypes of E. bieneusi infection in cattle in the Republic of Korea. Therefore, this study investigated the prevalence and genotypes of E. bieneusi circulating in pre-weaned Korean native calves and determined the age pattern of E. bieneusi infection and the relationship between E. bieneusi infection and diarrhea. MethodsThe prevalence of E. bieneusi infection in pre-weaned Korean native calves was screened by polymerase chain reaction. PCR-positive products were sequenced to determine the genotype of E. bieneusi. A Chi-square analysis used to compare the associations between diarrhea and infection rate of E. bieneusi in each age ranges or all ages. ResultsPCR and sequencing analysis revealed an overall prevalence of E. bieneusi of 16.9% (53/314) in preweaned calves. The prevalence of E. bieneusi was the highest in September (36.2%), followed by March (28.3%). E. bieneusi infection (χ 2 = 5.82, P = 0.016) was associated with diarrhea in calves. Our results also indicated that E. bieneusi infection was statistically associated with calf age (χ 2 = 11.61, P = 0.003), and the prevalence of E. bieneusi infection was significantly higher in calves aged 21−40 days (odds ratio = 2.90, 95% confidence interval: 1.54−5.45; P = 0.001) than in those aged 1−20 days. Interestingly, the association between E. bieneusi infection and diarrhea was observed only in calves aged 1−20 days (χ 2 = 5.82, P = 0.010). Furthermore, our results indicated that E. bieneusi infection in pre-weaned calves may be associated with mild diarrhea rather than severe diarrhea. We identified five genotypes, BEB4 (n = 12), BEB8 (n = 23), CHN6 (n = 1), I (n = 1), and J (n = 16), and all of which belonged to Group 2. The genotype BEB8 was the most prevalent among all age groups irrespective of diarrhea. In contrast, the genotype I was identified only in one calf aged 10 days with diarrhea. Except for CHN6, the other four genotypes were mostly observed in cattle, and all exhibited zoonotic potential.

Background: Enterocytozoon bieneusi is the most common species of microsporidia that can infect humans and various animals worldwide. To date, information on the prevalence and genotypes of E. bieneusi infection in cattle in the Republic of Korea is limited. Therefore, in this study, we aimed to investigate the prevalence and genotypes of E. bieneusi circulating in pre-weaned Korean native calves and determine the age pattern of E. bieneusi infection and the relationship between E. bieneusi and diarrhea.Results: The overall prevalence of E. bieneusi was 16.9% (53/314) in pre-weaned calves by PCR. The prevalence of E. bieneusi was the highest in September (36.2%), followed by March (28.3%). E. bieneusi infection (c 2 = 5.82, P = 0.016) was associated with diarrhea in calves. The present results indicated that E. bieneusi infection was statistically associated with calf age (c 2 = 11.61, P = 0.003); the prevalence of E. bieneusi was significantly higher in calves aged 21-40 days (odds ratio = 2.90, 95% confidence interval: 1.54-5.45; P = 0.001) than in those aged 1-20 days. Interestingly, E. bieneusi infection showed an association with diarrhea only in calves aged 1-20 days (c 2 = 5.82, P = 0.010). Five genotypes, BEB4 ( n = 12), BEB8 ( n = 23), CHN6 ( n = 1), I ( n = 1), and J ( n = 16), were identified, and all these genotypes belonged to Group 2. The genotype BEB8 was the most prevalent in all age groups regardless of diarrhea. On the other hand, the genotype I was identified only in one calf aged 10 days with diarrhea. Except for CHN6, the four other genotypes were mostly observed in cattle, and all of them have zoonotic potential.Conclusions: This is the first report of the genotypes BEB4 and CHN6 in pre-weaned Korean native calves. The results revealed the presence of zoonotic E. bieneusi in pre-weaned Korean native calves, demonstrating that cattle may play an important role as a reservoir host in E. bieneusi transmission to humans. association. A P value of £0.05 was considered to be statistically significant. Abbreviations E. bieneusi Enterocytozoon bieneusi; CI:confidence interval; C. parvum; Cryptosporidium parvum; G. duodenalis:Giardia duodenalis; ITS:internal transcribed spacer; OR:odds ratio; ROK:Republic of Korea Declarations Ethics approval and consent to participate This study did not receive approval from the Institutional Animal Care and Use Committee (IACUC) at Kyungpook National University, because the IACUC at this University evaluates laboratory animals maintained within indoor facilities and not at outdoor animals. A local veterinarian took all fecal samples and sent them to us.