Monday, June 7, 2021

Case of the Week 642

It's time for our monthly case from Idzi Potters and the Institute of Tropical Medicine, Antwerp. As always, Idzi has a great case for us - courtesy of Anna Rosanas and Pieter Guetens from ITM's Malariology Department: a patient with extensive recent travel - leaving Belgium to trek across rural areas of Peru, Niger, Mali, and finally the Philippines. He didn't take any malaria prophylaxis while traveling and now presents with fever and general malaise after being home for 3 weeks. The following are thick and thin Giemsa-stained blood films from this patient (pH 8.0). The percent parasitemia was calculated at 1%. Identification?


Sir Galahad said...

Plasmodium malariae. Trofozoiti, schizonti,gametociti.

Hisar fan said...

Band forms also visible.

Luis said...

P. Malariae

Luis said...

P. Malariae

Sheldon Campbell said...

Dual infection, falciparum + malariae. At least.

Blaine A. Mathison said...

This is a rather challenging one, but I am leaning towards Plasmodium malariae based on:
1. no obvious enlargement of iRBCs
2. apparent band forms
3. schizonts with <12 merozoites
4. thicker rings

Plasmodium malariae also occurs in all four countries listed.

I got a kick out of 'trekking through Peru, Niger, Mali, and Philippines' - those must have been some looooooooooooong suspension bridges :-D

Blaine A. Mathison said...

After I posted I read others' comments.

Sheldon's suggestion of a mixed infection is likely, given the expanded travel history.
I don't specifically see evidence of P. falciparum (the first thin film has an applique form, but that in itself is not definitive for Pf).

Based exclusively what I see in these pics, my ID would be P. malariae, but after examination of more fields, PCR might be in order to r/o mixed infection.

Anonymous said...

All microscopic characteristics point towards a P. malariae, the infected red cells are either normal or smaller in size. I do see a precautionary need to have a PCR to rule out a mixed infection with P.falciparum.
Florida Fan

Anonymous said...

New to this, but could P. knowlesi be a possibility based on travel history to the Philippenes, the falciparum-like trophozoites and malariae-like mature forms?

Pamela Durán said...

Plasmodium malariae, typical stages

Dr EM said...

It's a fantastic case. Thanks Dr Pritt.
And also challenging.
I think it is a differential diagnosis of P. malariae and P. Knowlesi
Confirmation is by performing PCR.

No evidence of p. falciparum.
Features are typical of p. malariae
and the similar p. Knowles

Blaine Mathison said...

With regards to P. knowlesi, the schizonts do not look right. Typical mature schizonts have elongated merozoites appearing segmented. I have only seen P. knowlesi three times, and this doesn't grab me for it off-hand.

Still with limited images and broad travel history, anything is possible

Bernardino Rocha said...

Well i think this a case of Plasmodium knowlesi. In the 3rd image we can see a trophozoite in "appliqué" form (similar to the early stages of P. falciparum), the merozoites and band form mimic those of P malariae (later stages). Sometimes leads to the erroneous diagnosis of P. falciparum/P. malariae mixed infection.

Unknown said...

All microscopic characteristics suggest P. malariae but the travel history and the parasitemia of the order 1% support P. knowlesi. Differential diagnosis of P. malariae / P. Knowlesi required through PCR.

Marco Ligozzi