Babesia microti Transmission Risk Through Ixodes persulcatus Ticks in Selenge, Mongolia, and Investigation of Its...

Babesia microti, a causative agent of human babesiosis, a tick-borne zoonotic disease, has been detected in Ixodes persulcatus ticks in Mongolia. Large-scale surveys of B. microti in ticks and its infectivity in rodents are essential. Of 458 I. persulcatus ticks, 94 females and 176 males were screened for B. microti infection, while 111 female and 77 male ticks were used to investigate B. microti transmission to BALB/c mice and hamsters. The prevalence of B. microti was higher in female ticks (26.6%) than in males (13.1%), with nearly one-sixth (17.8%) of ticks carrying the parasite. The infectivity of Mongolian isolates, as a sister clade to the U.S. lineage, remains unclear, as they failed to infect rodents. Our study suggests that the risk of B. microti transmission is approximately of one-sixth of I. persulcatus ticks, with a higher risk observed in females than in males.