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Table 3 Agreement in faecal egg counts (FECs) between initial reading and second quality control reading of Kato-Katz thick smears according to two different guidelines

From: Quality control in the diagnosis of Trichuris trichiura and Ascaris lumbricoides using the Kato-Katz technique: experience from three randomised controlled trials

  WHO guideline a Swiss TPH guideline a
  Trichuris trichiura Ascaris lumbricoides Trichuris trichiura Ascaris lumbricoides
Total number of Kato-Katz thick smears (positive/negative) 1,445 (1,189/256) 1,445 (297/1,148) 1,445 (1,189/256) 1,445 (297/1,148)
1. No. of Kato-Katz thick smears with difference in FECs (%) 345 (23.9%) 148 (10.2%) 97 (6.7%) 108 (7.5%)
2. No. of Kato-Katz thick smears with differences in presence/absence of helminth eggs (%) 51 (3.5%) 32 (2.2%) 51 (3.5%) 32 (2.2%)
3. No. of Kato-Katz thick smears with difference in FECs (%) among samples with egg counts 345 (29.0%) 148 (49.8%) 97 (8.2%) 108 (36.4%)
4. No. of Kato-Katz thick smears with differences in presence/absence of helminth eggs (%) among samples with egg counts 51 (4.3%) 32 (10.8%) 51 (4.3%) 32 (10.8%)
1. and/or 2. (%) 381 (26.4%) 164 (11.4%) 145 (10.0%) 130 (9.0%)
No. of Kato-Katz thick smears with discrepancies according to respective guidelineb (%) 345 (23.9%) 164 (11.4%) 145 (10.0%) 130 (9.0%)
3. and/or 4. and proportion as percentage (%) among Kato-Katz thick smears with positive egg counts 381 (32.0%) 164 (55.2%) 145 (12.2%) 130 (43.8%)
No. of Kato-Katz thick smears with discrepancies according to respective guidelineb (%) among Kato-Katz thick smears with positive egg counts 345 (29.0%) 148 (49.8%) 145 (12.2%) 130 (43.8%)
  1. aSee Table 1 for definition of the WHO and Swiss TPH guidelines.
  2. bThe WHO guideline state that differences which exceed 10% and more than four eggs require re-reading (see Table 1). However, in contrast to the Swiss TPH guideline, differences in presence/absence of helminth eggs are not explicitly stated. Therefore we assumed that differences in presence/absence of helminth eggs do not require re-reading as long as the difference does not exceed four eggs.