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Presentation outline

  1. Introduction and Overview (Mr. Paul Oboth)

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  • Reporting based on Parasite density using thick and thin film (Mr. Kagga Twaahah)

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  • Reporting based on plus and Parasite per field (Mr. Olinga John Bosco)

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  • Policy guidelines on diagnostics (Dr. Bosco Agaba)

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Reporting Malaria results

  • Calculating the parasite density (thin and thick) - most commonly-used, well-understood procedure (WHO recommended method)

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  • Using the plus (+) - subjective assessment with often variable results (not recommended by WHO)

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  • Parasites per field

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  • % parasitised RBC – time consuming but sometimes used in research settings**

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Parasite density (Thick & thin films)

  • Thick film
    • RBCs lysed (absent)

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  • Thin film –
    • RBCs intact (fixed)

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Traversing the thick film (WHO SOP)

  • Start the count in the top left-hand section of the film, look for a typical field with both parasites and WBC, move in a cross-sectional manner

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  • Continue counting in fields, do not overlap fields

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Counting in thick films using WBCs

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  • Count a minimum of 200 or 500 WBC

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  • Multiply # MP counted x 8,000 (average # WBC/µL blood) and divide by # WBC counted

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Parasite quantitation in the thick film

number of MP x 8,000 WBC

number of WBC

= number of parasites/µL

95 MP x 8,000 WBC

502 WBC

= 1,514 parasites/µL

Formula: Example:

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  • Count as many RBC & PRBC* as you have time for, or according to your SOPs
  • Count 20 fields of ~250 RBC
  • Multiply # PRBC counted x 5,000,000 (average # RBC/µL blood) and divide by # RBC counted

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Parasite quantitation in the thin film

number of PRBC x 5,000,000

20 fields x 250 RBC

= number of parasites/µL

Formula:

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* PRBC = Parasitised RBC

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The “Plus” Method

  • Most commonly used at our health facilities

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  • Examines parasites in a given number of fields

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  • Does not give a numeric density, only a relative one
    • +: 1 parasite/field in each/some of the 100 fields

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    • ++: 2 – 19 parasires per field

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    • +++: 20 or more parasites per field

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Parasites per field

  • Count the number of Malaria parasites per field.

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  • Establish the average.

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  • Report the parasite count per field

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Reporting/interpreting

  • Plasmodium parasites seen (Plus or numbers)
  • Species seen (Pf, Pv, Po, Pm)
  • Developmental stages seen (trophozoites, schizonts, gametocytes )
  • Parasite density (parasites/200 WBC or per micro- litre of blood)-WHO recommended

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What do think about this reporting?

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What do you think about this reporting?

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What do you think about this reporting?

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What do you think about this reporting

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Q&A Session ?

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