Malaria Blood Slides, Quick Lesson

I just learned how to ID species of malaria using blood slides, and I figured I should write it down before I forget.

First, there are 2 types of blood slides- thin and thick. You start by putting a drop of blood on a glass slide, then depending on whether or not you want thin or thick slides, you do different procedures:

Thick:
Let the blood dry. Pour your stain (Giemsa or whatever) on the blood spot, which does 2 things- 1) lyse the red blood cells, thus releasing any malaria parasites that were hiding in the RBC's 2) makes the parasites and white blood cells really really purple, so you can see them. Thick slides are the first thing you do usually because with the lysing, you can say either yes the person is infected or no there are no parasites in the blood.

Thin:
Smear the blood across the glass slide, then let it dry and then dip in a fixative which protects the red blood cells from lysing (methanol). Pour your stain on top, and then let it sit for varying amounts of time, depending on what stain you use. Making a thin slide often happens after you've done a thick slide, and you want to determine what strain of malaria you have (plasmodium comes in 4 strains for humans- falciparum, malariae, vivax, and ovale). With the thin slide you can see what the malaria parasite looks like when it's still in the RBC, and this helps you tell which one of the four you have.

Here are pictures that I took through the viewing lens of the microscope:

1) Thick Smear, PF. The very small specks are the malaria parasite lysed from the RBC's. The huge purple dots are white blood cells (they don't lyse, just dye very well). One clue that this person is infected with Plasmodium Falciparum (PF) is that the parasites are very small (compared to something I'll show next).



2) Thick Smear, PM. Yet again, you can see the big WBC sitting in the top left hand corner. The larger more clumpy dots (little grape bunches or something like that) are pretty different from the PF dots we saw above- according to the microscopist Kilama, this is a big tip to the experienced microscopist that this is not PM and a thin smear is needed to do strain typing.



3) Thin Smear, PF. You can see that there are these large purple round dots, which are the RBC's. This is what a PF thin smear looks like- sometimes you get RBC's with wavy edges and some smaller structures inside of them. Apparently with vivax and ovale you would see "sand" in the RBC itself, and it would be all dotted- then to distinguish vivax from ovale, ovale makes the RBC stretch into funny shapes while vivax stays rounder (I think, don't quote me on that).



4) Thin Smear, PM. Plasmodium Malariae has a very unique and distinctive look when it's in a RBC- one of its stages is a long band, which you can see below. This came from one of the students who is in one of the studies being done- the student came in this morning, so I was pretty lucky to even see this. PF is by far the more common malaria infection, and malariae happens more rarely.


That's it. See if anyone will hire you as a microscopist now (though Kilama says an expert microscopist needs 4 years of work at this... haha).