Case #279 – July, 2010

While examining a malaria-positive smear on a patient from Uganda, microbiologists at the Ontario Agency for Health Protection and Promotion observed what they believed to be a microfilaria. Images were captured and sent via email to the DPDx Team for diagnostic assistance. Figure A shows the object of interest, which measured approximately 200 micrometers in length. Figures B and C show close-ups of the anterior and posterior ends, respectively. What is your diagnosis? Based on what criteria?

Figure A

Figure B

Figure C

This was a case of perstans filariasis caused by Mansonella perstans. Diagnostic morphologic features included:

an unsheathed microfilaria within the size range for the species (190-200 micrometers in length).
a compact column of nuclei.
a blunt tail that contains nuclei to the end of the tail (Figure C).