Babesia sp. MO1

Yabsley, Michael J. & Shock, Barbara C., 2013, Natural history of Zoonotic Babesia: Role of wildlife reservoirs, International Journal for Parasitology: Parasites and Wildlife 2, pp. 18-31 : 23

2.1.4. Babesia sp. MO1

Babesia sp. MO1 is a rare cause of babesiosis in the United States. In 1992, this novel Babesia species was detected in a splenectomized patient in Missouri ( Herwaldt et al., 1996). Despite treatment (quinine and clindamycin), the patient died 13 days after diagnosis. Two additional cases of Babesia sp. MO 1 in splenectomized patients, both nonfatal, have been reported in Kentucky and Washington ( Beattie et al., 2002; Herwaldt et al., 2004). The natural hosts of this Babesia sp. appear to be lagomorphs. In Massachusetts, 16% of eastern cottontail rabbits ( S. floridanus ) were positive ( Goethert and Telford, 2003) and related Babesia sequences were subsequently found in desert cottontails ( Sylvilagus audubonii ) and black-tailed jackrabbits ( Lepus californicus ) from Texas ( Yabsley et al., 2006b). Ixodes dentatus is a competent vector and transmission to rabbits is temporally correlated with peak I. dentatus larvae activity ( Goethert and Telford, 2003). I. dentatus is a common tick on rabbits and birds and it will feed on people, although rarely ( Harrison et al., 1997; Hamer et al., 2011).

Initial phylogenetic analyses on a fragment of the 18S rRNA gene indicated that the Babesia sp. (MO1) was closely related to B. divergens , leading to concern that this European parasite had been introduced into the United States. Subsequent analyses proved that Babesia sp. MO1 is distinct from B. divergens from Europe based on the additional sequence analysis, lack of infectiousness to cattle, distinct morphology when grown in vitro, and erythrocyte in vitro specificity ( Holman et al., 2005; Holman, 2006).