In vitro cultivation of Babesia duncani (Apicomplexa: Babesiidae), a zoonotic hemoprotozoan, using infected blood from Syrian hamsters (Mesocricetus auratus)

Abstract

Human babesiosis, a tick-borne disease similar to malaria, is most often caused by the hemoprotozoans Babesia divergens in Europe, and Babesia microti and Babesia duncani in North America. Babesia microti is the best documented and causes more cases of human babesiosis annually than all other agents combined. Although the agents that cause human babesiosis are considered high-risk pathogens in transfusion medicine, federally licensed diagnostics are lacking for B. duncani in both the USA and Canada. Thus, there has been a need to develop and validate diagnostics specifically for this pathogen. In this study, B. duncani (WA1 isolate) was cultivated in vitro from Syrian hamster (Mesocricetus auratus) infected blood. We hypothesized HL-1 media with supplements would result in B. duncani propagating at higher levels in culture than supplemented M199 similar to the medium the parasite was originally cultivated with in 1994. We were unable to recreate Thomford's cultivation results with the M199 medium but supplemented HL-1 medium was able to successfully establish continuous culture. We further hypothesized that RBC from species other than hamsters would support B. duncani in vitro. However, rat, mouse, horse, and cow RBC did not support continuous culture of the parasite. Culture stocks of B. duncani were deposited at BEI Resources and are now commercially available to the scientific community to further research. The cultured parasite developed in this study was instrumental in the adaptation of B. duncani continuous culture to human RBC.

Keywords: Babesia duncani; Human babesiosis; Percentage of parasitized erythrocytes (PPE); Tick-borne disease; Transfusion.