In vivo assays for drug resistance in Babesia divergens using the Mongolian gerbil, Meriones unguiculatus.

Two in vivo drug resistance assays were developed using gerbils. Cross resistance, involving related babesicides as well as the chemically unrelated antibiotic, oxytetracycline, was demonstrated, but the suggestion that imidocarb may select for pathogenic strains of parasites was not supported. Limited tests of field strains did not detect resistance. It is suggested that an in vitro assay would be more appropriate for surveys through in vivo assays would be essential for confirmatory studies.