Zoonotic potential of Enterocytozoon bieneusi in pre-weaned Korean native 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.[Figure not available: see fulltext.]