Blood Films & Smears Flashcards
Looking at thick & thin blood films and Smear impressions from Aspirates
Trypanosoma Cruzi
Trypomastigotes
Chunky kinetoplasts
Haemoflagellate/Blood protozoa causing Chagas Disease
Vector: Panstrongylus Triatomine bugs
Thin blood film
Trypanosoma brucei
Trypomastigotes
Small kinetoplasts
Haemoflagellate/Blood protozoa causing Human African Trypanosomiasis (HAT) or African Sleeping Sickness
Vector: Glossina Tsetse Fly
Thin blood film
P.vivax
Trophozoite
Enlarged RBC with irregular ring & Schuffners dots
P.vivax
Gametocyte
Filling the whole enlarged RBC
P.vivax
Gametocyte on the left
Schizont on the right
Both are enlarged RBC’s
P.falciparum
Trophozoites
See double chromatin (headphones) & accole forms in normal sized RBC
P.falciparum
Trophozoite
Neat parasite with Maurer’ clefts in normal sized RBC
P.falciparum
Trophozoites
Neat rings with Maurer’s clefts in normal sized RBC
& an accole form
P.vivax
Trophozoite
Enlarged RBC with untidy parasite, Schuffners dots & some pigment
P.malariae
Gametocyte
Smaller RBC completely filled
P.vivax
Schizont
Enlarged RBC with Schuffners dots & pigment
P.ovale
Gametocyte
Oval, fimbriated cell with coarse James’ dots & parasite does not fill the cell
P.ovale
Gametocyte
Slightly fimbriated cell with coarse James’ dots & parasite does not fill the slightly enlarged cell
P.vivax
Early schizont
Enlarged, plastic cell with untidy parasite with 2 nuclei & schuffners dots
P.falciparum
Schizont
Normal sized RBC containing maurer’s clefts, neat parasite with multiple nuclei that does not fill the cell & a clump of black pigment
P.falciparum
Schizont
Normal sized RBC containing neat parasite with multiple nuclei that does not fill the cell & a clump of black pigment
P.vivax
Trophozoite
Enlarged RBC, Schuffners dots, irregular/untidy parasite
P.vivax
Trophozoite
Enlarged, plastic RBC with Schuffners dots & untidy/irregular cytoplasm
Leishmania
Amastigotes
Seen outside RBC’s
Thin blood film
Leishmania
Promastigotes
Seen outside RBC’s
Position of the kinetoplast near flagellum
Thik blood film
P.falciparum
Trophozoite
Accole form with Maurer’s clefts
How do you calculate parasitaemia percentage?
- Count the number of parasitised cells (not number of parasites) in a field of view
- Count the number of parasitised cells (X) in 8 consecutive fields, either in an upwards or downwards direction.
- Calc %=(X÷2)/10
ALWAYS calculate percentage parasitaemia for P.falciparum infections
There are ~250 RBC’s per field of view
P.falciparum
Trophozoite
Headphones in normal sized RBC
P.falciparum
Trophozoites
Multiple parasites in normal sized RBC - 2x accole forms
What does this show?
Plasmodium spp. on Thick Blood Film
The WBC’s are purple and the background is pale. The RBC’s are lysed, releasing the parasites
Brugia timori microfilariae
on Thick Blood Film
Large microfilariae
Has a sheath that stains pink
3 nuclei in tail (.’. Tri-nucleated for Timori)
Disease: Lymphatic Filariasis
Vector: Culicine Mosquitoes
Tx: DEC (diethylcarbamazine) +/- Doxy
Thick bloodfilms for microfilariae, also stained with Giemsa
Onchocerca volvulus microfilariae
on Dry smear impressions from skin snip
Large microfilariae
NO sheath
Empty globular head & empty blunt tail (O = nothing .’. empty)
Disease: Subcutaneous Filariasis & Onchocerciasis - River blindness
Vector: Simulium Black fly
Tx: Ivermectin +/- Doxy. NOT DEC.
(Caution if Loaloa coinfection)
Also stained with Giemsa
Brugia malayi microfilariae
on Thick Blood Film
Large microfilariae
Has a sheath that stains pink
2 nuclei in tail (.’. Bi-nucleated for Brugia)
Disease: Lymphatic Filariasis
Vector: Culicine Mosquitoes
Tx: DEC (diethylcarbamazine) +/- Doxy
Thick bloodfilms for microfilariae, also stained with Giemsa
Brugia malayi microfilariae
on Thick Blood Film
Large microfilariae
Has a sheath that stains pink
2 nuclei in tail (.’. Bi-nucleated for Brugia)
Disease: Lymphatic Filariasis
Vector: Culicine Mosquitoes
Tx: DEC (diethylcarbamazine) +/- Doxy
Thick bloodfilms for microfilariae, also stained with Giemsa
Wucheria bancrofti microfilariae
on Thick Blood Film
Large microfilariae
Has a sheath that stains pink
NO nuclei in tail
Disease: Lymphatic Filariasis
Vector: Culicine Mosquitoes
Tx: DEC (diethylcarbamazine) +/- Doxy
Dx: optimum time is at night (between 22:00-02:00)
Thick bloodfilms for microfilariae, also stained with Giemsa
Wucheria bancrofti microfilariae
on Thick Blood Film
Large microfilariae
Has a sheath that stains pink
NO nuclei in tail
Disease: Lymphatic Filariasis
Vector: Culicine Mosquitoes
Tx: DEC (diethylcarbamazine) +/- Doxy
Dx: optimum time is at night (between 22:00-02:00)
Thick bloodfilms for microfilariae, also stained with Giemsa
Loaloa microfilariae
on Thick Blood Film
Large microfilariae
Has a sheath that does NOT stain pink .’. Ghost sheath
Many nuclei in tail which go to the tip
Disease: Subcutaenous Filariasis & African Eyeworm
Vector: Chrysops deer fly
Tx: Albendazole to dec. Mf then DEC
(DEC & IVM can produce severe SE’s in high Mf counts)
Thick bloodfilms for microfilariae, also stained with Giemsa
What does this show?
Plasmodium spp. on Thick Blood Film
There is a large, dark purple WBC, a small pink platelet and a parasite with a dark purple nuclei & blue cytoplasm, on a pale background. The RBC’s are lysed, releasing the parasites.
Plasmodium spp. Trophzoites
on Thick Blood Film
There are 2x parasites with a dark purple nuclei & blue cytoplasm, on a pale background.
The RBC’s are lysed, releasing the parasites.
P.falciparum
Gametocyte
on Thick Blood Film
There is a neat banana shaped parasite, on a pale background where the RBC has lysed, releasing the parasite.
Difficult to speciate on thick films due to loss of RBC features
P.vivax
Trophozoite
on Thick Blood Film
There are untidy parasites, on a pale background where the RBC has lysed, releasing the parasite.
The pink skirt surrounding them is the remnants of the Schuffner’s dots, giving you an idea of how large the RBC’s would have been.
Difficult to speciate on thick films due to loss of RBC features
Which blood films are more sensitive for Plasmodium spp.?
Thick blood films
Thick blood films are not fixed with methanol in order to lyse the RBC’s
Which blood films are better for estimating Plasmodium spp. percentage parasitaemia?
Thin blood films
You can’t estimate a percentage parasitaemia from a thick film as there are no red blood cells.
A percentage parasitaemia should always be calculated for which infections?
Plasmodium falciparum
P.falciparum
Gametocyte
Neat banana shaped parasite with fine membrane from RBC
P.malariae
Schizont
Classic ‘Daisy head’ schizont with 8-10 merozoites, central pigment, filling the whole RBC which is slightly smaller in size.
P.falciparum
Trophozoite
Neat parasite with Maurer’s clefts in normal sized RBC.
P.malariae
Gametocyte
See nucleus with scattered yellow/gold pigment in smaller RBC.
Usually they fill the whole cell but there are no dots/stippling in cytoplasm which indicates P.malariae
P.ovale
Trophozoite
Neat parasite with thick loop of cytoplasm in normal sized RBC with fimbriations an coarse James’ dots.
P.vivax
Schizont
18-20 Merozoites filling the whole enlarged RBC with scattered pigment.
Can just see schuffners dots around the peripheries.
P.vivax
Trophozoite
Ring parasite with Schuffners dots in enlarged RBC.
P.ovale
Schizont
Oval shaped RBC containing perfectly round parasite with merozoites and pigment, that does not fill the whole cell.
May also see fimbriations
P.vivax
Gametocyte
Enlarged RBC completely filled by parasite with nucleus and scattered pigment.
Can see Schuffners dots around peripheries of cell
Lymphocyte
Do not confuse with P.vivax Gametocyte - cell is large but much darker than parasite and there is no nucleus or pigement
Echinococcus protoscoleces
Larval stage of canid tapeworm causing hydtid disease
very small – see under x40
Can also see loose hooks in hydatid cyst aspirates
Wet aspirate: fluid from Hydatid cysts aka ‘Hydatid Sand’ (Condenser 2)
Echinococcus protoscoleces
Larval stage of canid tapeworm causing hydatid disease
very small – see under x40
Invaginated head & can clearly see hooks inside.
Wet aspirate: fluid from Hydatid cysts aka ‘Hydatid Sand’ (Condenser 2)
