Monthy Case Studies - 2014
Case #370 - April, 2014
A 21-year-old female presented with swelling of the eyelid, wrist, and knee. The symptoms started after returning from a three-month trip to Cameroon in 2011. A blood specimen was collected by her health care provider at 11:30 A.M. and smears were made and stained (NOS). Her eosinophilia at the time was 48%. A filarial IgG4 antibody test performed a month prior and was negative. Two worm-like structures were observed by laboratory technicians after scanning 10 stained thick smears. Images of both structures were captured (Figures A and B) and shared with CDC personnel. As follow-up to the images, a tube of EDTA blood was sent to the DPDx Team for further evaluation. Figure C shows what was found on a wet mount of the blood; Figures D and E are from thick and thin Giemsa-stained smears, respectively. What is your diagnosis? Based on what criteria?
Acknowledgements: This case and images (in part) were kindly provided by Purdue University, Indianapolis, IN.
Answer to Case #370
This was a case of loiasis caused by Loa loa. Morphologic features shown included:
- presence of microfilariae in blood collected during the day.
- robust microfilariae with a short head space and a tapered tail with nuclei spaced irregularly to the tip of the tail (Figures A, B, D, and E)
- evidence of a sheath that did not stain with Giemsa (Figure C)
More on: Loaisis
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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.