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Table 1 Detection of anti-DENV IgM by two commercial ELISA tests at initial survey, 6 and 12 months

From: Prolonged persistence of IgM against dengue virus detected by commonly used commercial assays

  No. DENV IgM positive/total (%)a
Initial 6 months later 12 months later
  SDb Focusc SDb Focusc SDb Focusc
All 44/44 (100.0) 40/44 (90.9) 31/44 (70.5) 6/44 (13.6) 18/39 (46.2) 3/39 (7.7)
p-valued   < 0.0001 < 0.0001
Age
 20–50 12/12 (100.0) 8/12 (66.7) 9/12 (75.0) 2/12 (16.7) 5/10 (50.0) 1/10 (10.0)
 51–60 16/16 (100.0) 16/16 (100.0) 12/16 (75.0) 2/16 (12.5) 7/16 (43.8) 1/16 (6.3)
  > 60 16/16 (100.0) 16/16 (100.0) 10/16 (62.5) 2/16 (12.5) 6/13 (46.2) 1/13 (7.7)
 p-valued 0.7676 > 0.9999 > 0.9999 > 0.9999
Sex
 Male 7/7 (100.0) 7/7 (100.0) 6/7 (85.7) 1/7 (14.3) 2/5 (40.0) 1/5 (20.0)
 Female 37/37 (100.0) 33/37 (89.2) 25/37 (67.6) 5/37 (13.5) 16/34 (47.1) 2/34 (5.9)
 p-valued 0.6542 > 0.9999 > 0.9999 0.3452
Initial IgM levele
  > Median 22/22 (100.0) 22/22 (100.0) 19/22 (86.4) 5/22 (22.7) 12/19 (63.2) 3/19 (15.8)
  < Median 22/22 (100.0) 18/22 (81.8) 12/22 (54.5) 1/22 (4.5) 6/20 (30.0) 0/20 (0.0)
 p-value§ 0.0452 0.1853 0.0562 0.1060
Diagnosed cases
 Yes 17/17 (100.0) 16/17 (94.1) 11/17 (64.7) 1/17 (5.9) 7/15 (46.7) 1/15 (6.7)
 No 27/27 (100.0) 24/27 (88.9) 20/27 (74.1) 5/27 (18.5) 11/24 (45.8) 2/24 (8.3)
 p-valued 0.5205 0.3801 > 0.9999 > 0.9999
  1. aNumber of positive anti-DENV IgM/number of specimens tested (percentage)
  2. bELISA kits manufactured by Standard Diagnostics
  3. cELISA kits manufactured by Focus Diagnostics
  4. dThe difference in the detection rate among different groups were examined using Fisher’s exact tests
  5. eThe initial anti-DENV IgM level was defined by subtracting the mean the OD values of the negative controls in each plate from the mean OD values of the samples using the SD ELISA