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Case #476 - September, 2018

A 27 year-old female sought emergency medical attention due to a foreign object in her eye. Medical personnel removed the object, captured images and submitted to the DPDx Team for diagnostic assistance for what is shown in Figures AD. What is your diagnosis? Based on what criteria?

(This case and images was kindly provided by San Pedro Hospital, Logroño, Spain.)

parasitic image

Figure A

parasitic image

Figure B

parasitic image

Figure C

parasitic image

Figure D

parasitic image

Figure E

Case Answer

This was a case of ocular myiasis caused by Oestrus ovis, the sheep botfly. Diagnostic features shown in the images were:

  • Cylindrical, swollen or heavy-looking anterior end
  • Backward projecting thick spines in widely spaced bands around the body
  • Location in patient/host*

*Adult females of O. ovis are larviparous and deposit their larvae directly into the nasal cavities of the normal host (sheep).  Larvae then move to the frontal sinuses and attach to the mucous membrane.  When mature, they leave the host to form puparia in the soil.  In humans, eggs are often laid directly into the conjunctiva by female flies. In humans, the larvae are usually only 1st instar when diagnosed.

More on myiasis: https://www.cdc.gov/dpdx/myiasis/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 education resource designed for health professionals and laboratory scientists. For an overview including prevention and control visit www.cdc.gov/parasites/.

  • Page last reviewed: October 31, 2018
  • Page last updated: October 31, 2018
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