Assessing Babesia Microti Sensu Lato in Small Mammals in Northeast Florida

Babesia microti is the causative agent of human babesiosis. Black-legged ticks (Ixodes scapularis) are the only proven vector and white-footed mice (Peromyscus leucopus) serve as the main reservoir in northeastern United States. The aim of the present study was to determine if B. microti is present in small mammals in southeastern United States and to compare strains found in this study to reference strains from around the world. Blood samples were obtained from cotton mice, cotton rats, a flying squirrel, golden mice, rice rats, Virginia opossums, wood rats, and raccoons in northeastern Florida. DNA was extracted from the blood, and portions of the B. microti DNA (from 18S and β-tubulin genes) were amplified via nested PCR assays. Of the eight species tested, only cotton rats and raccoons tested positive for B. microti. Representative samples of the amplified DNA from these two species were sequenced and compared phylogenetically to reference strains of Babesia species. The B. microti found in the cotton rats most closely resembles B. microti sensu stricto, which is pathogenic to humans, and the B. microti found in the raccoons most closely resembles other raccoon strains of B. microti