Case #446 – June, 2017

Blood specimens were collected at night from members of a village in Myanmar endemic for lymphatic filariasis. Roughly one-third of the cases were symptomatic, with or without recurrent episodes of fever and various degrees of lymphedema. The objects in Figures A and B were observed on Giemsa-stained thick blood films from a few of the asymptomatic cases at 500x oil magnification; Figures C and D show close detail of the object in Figure B at 1000x oil magnification. The objects measured on average 200 micrometers in length. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

Figure D

This was a case of lymphatic filariasis caused by Brugia malayi. Diagnostic morphologic features included:

microfilaria whose sheaths stained pink with Giemsa and within the size range for B. malayi (175-230 micrometers)
dense nuclear column in which individual nuclei are easily defined
microfilariae with a relatively long head space and a tail with terminal and subterminal nuclei (Figure D)

More on lymphatic filariasis

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.

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/.