The physician suspected Bruce had an infection due to the observation of ring and cross-shaped structures in his blood. An immuno-fluorescence assay (IFA) was conducted to detect Babesia, with results interpreted based on fluorescence microscopy. The presence of green indicates a positive test for Babesia, while black areas denote negative results.

1. Observation of the ring and cross-shaped structures in Bruce's blood made the physician suspect
infection with either Plasmodium spp. or Babesia spp. An immuno-fluorescence assay (IFA)
using an antibody specific for Babesia conjugated to a green fluorescent dye was performed and
then observed by fluorescence microscopy. Image is below. Interpret these results: You see
green, so this is positive for Babesia. You see green, so this is negative for Babesia. Black area
means negative, so no Babesia is present. Black area is positive, so Babesia is present.