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Table 2 Theoretical sensitivity of thick and thin blood films of surveyed laboratories (n = 50, MD = 27)

From: Malaria diagnosis in a malaria non-endemic high-resource country: high variation of diagnostic strategy in clinical laboratories in the Netherlands

Guideline/laboratory Total magnification (ocular × objective) Thick film Thin film
Volume of thick film Diameter of thick film Number of fields examined Theoretical total examined volume Theoretical limit of detection (based on 2 trophozoites) Theoretical fields examined Theoretical total examined volume Theoretical part of volume examined compared to thick film
Guideline * µL mm Number µL Trophozoites
/µL
Number µL %
NVP [9, 12] 1000 6 12 200 0.3 7.41 ND   
BSH [10] 1000^ Several drops 200    ND   
CDC [11] 1000^ Small drop 17.9** 100–300     
WHO [8] 1000 6 12 100 0.1 14.29 ND   
Range          
 Minimum 500 6 6 75 0.09 1.2 40 0.002 0.8%
 Maximum 1250 15 23.25* 413 1.65 21.9 600 0.056 10.3%
 Mean NA 8 14 207 0.47 7.4 190 0.010 3.4%
 Median NA 6 13 200 0.31 6.5 175 0.009 2.9%
Laboratory          
 A 1000 6 20 188 0.09 21.9 188 0.009 10.3%
 B 1000     263 0.013  
 C 500 6 15 175 0.60 3.3 175 0.018 2.9%
 D 1000 6 6 200 1.08 1.9 ND   
 E 1000     338 0.017  
 F 625     113 0.009  
 G 500     188 0.019  
 H 1000     188 0.009  
 I 1000 6 13 225 0.26 7.7 ND   
 J 1000 10     75 0.004  
 K 1000     275 0.014  
 L 1250 6 13 338 0.31 6.5 74 0.003 1.0%
 M 1000 6 15 200 0.17 11.6 200 0.010 5.8%
 N 1000 6 13 188 0.22 9.3 ND   
 O 1000     263 0.013  
 P 500 6 15 338 1.17 1.7 563 0.056 4.8%
 Q 500 6 13 225 1.04 1.9   
 R 500     125 0.006  
 S 625     413 0.009  
 T 1000 6 12 200 0.27 7.4 ND   
 U 1000     40 0.002  
 V 1000 6 11 200 0.32 6.2 ND   
 W 1000 10 23.25 200 0.12 16.7 75 0.004 3.1%
 X 1000 6 12 200 0.27 7.4 ND   
 Y 1000     113 0.006  
 Z 1000 10 9 413 1.65 1.2 413 0.021 1.3%
 AA 1000     75 0.004  
 AB 1000 6     49 0.002  
 AC 1000 20     263 0.013  
 AD 1000     113 0.006  
 AE 1000     263 0.013  
 AF 1000 6 12 200 0.27 7.4   
 AG 1000 15     49 0.002  
 AH 1000     263 0.013  
 AI 1000 15 14 135 0.33 6.0 135 0.007 2.0%
 AJ 1000     338 0.017  
 AK 1000     175 0.009  
 AL 1000     74 0.004  
 AM 1000     200 0.010  
 AN 1000 6 12 113 0.15 13.2 ND   
 AO 1000 6 10 200 0.39 5.1 200 0.010 2.6%
 AP 1000 6     75 0.004  
 AQ 1000 6     600 0.030  
 AR 1000     75 0.004  
 AS 625 15 16 75 0.45 4.4 ND   
 AT 1000     188 0.009  
 AU 1000 15     74 0.004  
 AV 1000 6 10 225 0.44 4.6 74 0.004 0.8%
 AW 1000 12 15 113 0.19 10.3 113 0.006 2.9%
 AX 1000     113 0.006  
  1. –: missing data; .: no calculation possible due to missing data; ND: not determined for the detection of parasites; NA: not applicable
  2. *The size of 1 euro coin
  3. **The size of a US dollar dime
  4. ^1000× magnification and FN 18 of the ocular is assumed, based on the use of a 100× objective