Saturday, August 6, 2011

Answer to Case 171

Answer: microfilaria of Wuchereria bancrofti

The first step in identifying this microfilaria is to recognize the presence of a poorly-staining sheath. The sheath is nicely demonstrated in images 3 and 4 of this case. This narrows your diagnosis down to one of the 3 following sheathed microfilariae:
1. Wuchereria bancrofti
2. Brugia spp. (sheath typically stains deep pink on Giemsa)
3. Loa loa

The next step is to look at the tail nuclei to differentiate the 3 microfilariae. Note in the image below that the nuclei do not extend to the tip of the tail. Therefore, this is consistent with W. bancrofti. (CLICK ON IMAGE TO ENLARGE)

I did not give you the size of the organism, but that is also a helpful differentiating feature.

Thank you everyone for your responses!

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