Case #514 – April, 2020
A 24-year-old female exchange student from Guinea reported to the clinic with headaches, itchy skin, and enlarged lymph nodes. She recalled multiple painful insect bites in her country prior to her travel to the United States. A rapid diagnostic test for malaria performed at the clinic was negative. Smears were subsequently made and stained with Wright-Giemsa. Figures A and B show what was observed on a thin blood smear at 1000x oil magnification. What is your diagnosis? Based on what criteria?
This was a case of African trypanosomiasis (African sleeping sickness) caused by a hemoflagellate belonging to the Trypanosoma brucei complex. Diagnostic morphologic features shown included:
- trypomastigotes with a centrally located nucleus, an undulating membrane, and a flagellum running along the undulating membrane.
- a small, anteriorly located kinetoplast.
- dividing form, demonstrated by presence of two kinetoplasts (black arrows, Figure B) and a dividing body (blue arrow, Figure B). Division is by longitudinal binary fission.
This was most likely Trypanosoma brucei gambiense given the patient’s country of origin and clinical presentation. It should be noted however, that Trypanosoma brucei gambiense is morphologically indistinguishable from Trypanosoma brucei rhodesiense.
More on African trypanosomiasis
Images presented in the dpdx case studies are from specimens submitted for diagnosis or archiving. On rare occasions, clinical histories given may be partly fictitious.
DPDx is an educational resource designed for health professionals and laboratory scientists. For an overview including prevention, control, and treatment visit www.cdc.gov/parasites/.