Answer to the Parasite Case of the Week 711: Plasmodium falciparum infection with high parasitemia. Primarily early stage trophozoites are seen, but a single (somewhat) banana-shaped gametocyte and possibly later stage trophozoites are often seen. Given the high level of parasitemia, it's not surprising that we are seeing some some extracellular forms. If there happens to be concern about an alternate diagnosis of babesiosis (i.e., if the travel history wasn't known), then PCR could be performed. In this case, the presence of hemozoin and elongated gametocytes allows us to rule out babesiosis from the differential diagnosis.
Florida Fan nicely describes this case as follows:
"The infected red cells are of all sizes; this shows that there’s no predilection either for young red cells or older red cells." (There are also no Schüffner's dots). "As such we can rule out P. vivax, ovale and malariae. The multiple infection with double rings, appliqué forms, and head phones orient us further into an identification of P. falciparum. The lone banana-shaped gametocyte further confirms P. falciparum being the causative agent. There is no morphology forms (or travel history) to indicate a possible monkey malaria. With such a high parasitemia this case is serious cause to emphasize the urgency that all malaria testing are to be a stat test 24/7."
Indeed, all cases of suspected malaria should be evaluated on a a STAT basis given the potential life-threatening nature of infection.
Here are some of the key identifying features of this case:
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