Answer to Case 658

Answer to theParasite Case of the Week 658:Trypanosoma bruceiGiven the travel history and rapid onset of symptoms,T. b. rhodesienseis the most likely parasite present. This case shows very high parasitemia with numerous trypomastigotes seen on the patient ' s thick blood film. Here is the corresponding thin blood film, highlighting some of the key diagnostic features:Note that the motile flagellate form (i.e., the trypomastigote) ofT. bruceidivides by binary fission in the peripheral blood. This is in contrast toTrypanosoma cruzi,the cause of American trypanosomiasis (a.k.a. Chagas disease), in which it is the non-motile tissue amastigote form that divides. Amastigotes are not seen withT. bruceiinfection.  When seen in the peripheral blood, the trypomastigotes ofT. bruceineed to be differentiated from those ofT. cruzi- particularly when the travel history is not known. Humans can also have transient asymptomatic parasitemia with some of the zoonotic trypanosomes.So what are the next steps? If there was a concern for mixed trypanosomiasis/malaria, then examination of a thin film (and/or PCR) would be indicated, as suggested by Murtadha Maradun Mohammad.If we are uncertain of the infectingTrypanosoma subspecies (e.g., if the patient was in Uganda where both T. b. rhodesiense and T. b. gambiense are present), then we could also perform serology or PCR as noted by John Markantonis and Harsha Sheorey.Importantly, LS noted that examinati...
Source: Creepy Dreadful Wonderful Parasites - Category: Parasitology Source Type: blogs