Thick vs Thin film comparison: Difference between revisions
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'''Navigation'''</br> | '''Navigation'''</br> | ||
<span style="font-size:90%">>[[MalariaETC_Index|Main Malaria Index]]''</span></br> | <span style="font-size:90%">>[[MalariaETC_Index|Main Malaria Index]]''</span></br> | ||
<span style="font-size:90%">>>[[ | <span style="font-size:90%">>>[[Thick film interpretation|Thick film - main page]]''</span></br> | ||
<span style="font-size:90%">>>>Current page: ''' | <span style="font-size:90%">>>>Current page: '''Thick film vs thin film'''</span> | ||
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<span style="font-size:160%; color:navy">Relative merits of thick or thin films in malaria diagnosis</br></span> | <span style="font-size:160%; color:navy">Relative merits of thick or thin films in malaria diagnosis</br></span> | ||
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<span style="font-size:90%;">There is no single correct choice of staining, essentially the thin film has many advantages in terms of ease of preparation, staining and identification. In contrast the thick malarial film offers a single but significant advantage: that of superior sensitivity for parasite detection. The images above show the merits of the techniques - the thin film resolves good parasite detail and also the features of the red cell allowing parasite size to be appreciated and any alterations to red cells to be seen and characterised. In contrast, the thick film resolves less parasite detail and no red cell features (in this example) but shows all parasites in a volume that is likely around 6-fold greater than the thin film.</span></br></br></br> | |||
<gallery mode="nolines" heights=200px widths=200px> | |||
File:PFET2g.jpg|<span style="font-size:80%">Thin film appearances ''P.falciparum''</span>|link={{filepath:PFET2g.jpg}} | |||
File:3_Trophs_HP.jpg|<span style="font-size:80%">Thick film appearances ''P.falciparum''</span>|link={{filepath:3_Trophs_HP.jpg}} | |||
</gallery> | |||
</br></br> | |||
<span style="font-size:90%;">The relative merits and drawbacks of the two approaches are outlined in the table below.</span> | |||
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<span style="font-size:100%;">'''TABLE: A COMPARISON OF THICK AND THIN FILMS'''</span></br></br> | |||
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!'''1. Sensitivity for detection''' | |||
|- | |||
| Thick film: Higher - can detect lower levels of parasitaemia ~5–10 parasites/µL | |||
|- | |||
| Thin film: Lower - generally requires ~50 parasites/µL for reliable detection | |||
|- | |||
!'''2. Species Identification''' | |||
|- | |||
| Poor: poor - red cell morphology is lost and species-specific features may not be seen | |||
|- | |||
| Thin film: Good - both parasite morphology and RBC characteristics are assessed | |||
|- | |||
!'''3. Quantification of parasite number''' | |||
|- | |||
| Difficult: red cells are not seen so requires estimation and is therefore imprecise | |||
|- | |||
| Easier: parasites can be counted counted directly and assessed as a proportion of red cells | |||
|- | |||
!'''4. Preparation and staining considerations''' | |||
|- | |||
| Less easy: requires air drying and careful spreading and staining to minimise any artefact | |||
|- | |||
| Easier: films are fixed and stained immediately with clearer morphology of parasites and red cells | |||
|} | |||
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Latest revision as of 11:08, 21 February 2025
Navigation
>Main Malaria Index
>>Thick film - main page
>>>Current page: Thick film vs thin film
Relative merits of thick or thin films in malaria diagnosis
There is no single correct choice of staining, essentially the thin film has many advantages in terms of ease of preparation, staining and identification. In contrast the thick malarial film offers a single but significant advantage: that of superior sensitivity for parasite detection. The images above show the merits of the techniques - the thin film resolves good parasite detail and also the features of the red cell allowing parasite size to be appreciated and any alterations to red cells to be seen and characterised. In contrast, the thick film resolves less parasite detail and no red cell features (in this example) but shows all parasites in a volume that is likely around 6-fold greater than the thin film.
-
Thin film appearances P.falciparum
-
Thick film appearances P.falciparum
The relative merits and drawbacks of the two approaches are outlined in the table below.
| 1. Sensitivity for detection |
|---|
| Thick film: Higher - can detect lower levels of parasitaemia ~5–10 parasites/µL |
| Thin film: Lower - generally requires ~50 parasites/µL for reliable detection |
| 2. Species Identification |
| Poor: poor - red cell morphology is lost and species-specific features may not be seen |
| Thin film: Good - both parasite morphology and RBC characteristics are assessed |
| 3. Quantification of parasite number |
| Difficult: red cells are not seen so requires estimation and is therefore imprecise |
| Easier: parasites can be counted counted directly and assessed as a proportion of red cells |
| 4. Preparation and staining considerations |
| Less easy: requires air drying and careful spreading and staining to minimise any artefact |
| Easier: films are fixed and stained immediately with clearer morphology of parasites and red cells |