The parasites known to cause babesiosis are shown here infecting red blood cells under the microscope. | Credit: Smith Collection/Gado / Contributor via Getty Images Typical symptoms of babesiosis ...

One of the vets went up to Callis and said, “Do you know you have red blood cells in that bone?” Sure enough, under a microscope, it appeared that the bone was filled with red disks.

A red blood cell is much smaller than that. To allow us to see detail in these cells, we need the help of a microscope.