Case #491 – May, 2019

A 42-year-old missionary worker, who is working in various western Pacific Islands, sought medical attention at a local health center for mild fevers and wheezing coughing episodes. A thick blood smear was prepared, stained with Giemsa, and examined for parasites. Figures A and B show what was observed in low numbers at 400x magnification. The objects measured approximately 260 micrometers in length on average. What is your diagnosis? Based on what criteria?

Figure A

Figure B

This was a case of lymphatic filariasis caused by Wuchereria bancrofti. Morphologic features presented in the images included:

sheathed microfilaria within the size range for W. bancrofti (note: the sheath is unstained but still visible in the images).
short head space.
a tail that is tapered to a point.
discrete nuclear column in the body that does not extend to the tip of the tail.

More on lymphatic filariasis: https://www.cdc.gov/dpdx/lymphaticfilariasis/index.html

Images presented in the dpdx case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.