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)

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Page last reviewed: July 19, 2017