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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 A

Figure B

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 monthly case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.

DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.

Page last reviewed: June 26, 2019