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Table 5 Association between age at the time of malaria episode and antibody levels and seroprevalence in 18 months old children

From: The impact of early life exposure to Plasmodium falciparum on the development of naturally acquired immunity to malaria in young Malawian children

Antigen tested/parasite isolate

No episodea (n = 457)

≥ 1 episode before 6 months of agea (n = 31)

p valueb

≥ 1 episode between 6 and 18 months of agea (n = 113)

p valueb

MSP1 19 kDc

2.36 (0.51, 5.73)

6.16 (1.92, 11.16)

0.0071

4.71 (1.43, 21.25)

<0.0001

224 (49.0)

24 (77.5)

0.002

79 (69.9)

<0.0001

MSP2d

2.76 (0.79, 8.23)

5.76 (1.01, 10.55)

0.1043

3.06 (1.06, 13.97)

0.3165

113 (24.7)

12 (38.8)

0.084

37 (32.7)

0.083

EBA175e

3.49 (1.96, 17.05)

3.25 (1.89, 8.79)

0.5785

3.19 (1.93, 9.91)

0.3753

50 (10.9)

3 (9.7)

0.827

16 (14.2)

0.338

Rh2A9f

7.03 (3.97, 13.13)

8.24 (4.41, 17.32)

0.3790

7.92 (4.12, 15.87)

0.2223

108 (23.6)

10 (32.3)

0.278

33 (29.2)

0.219

Schizont

2.95 (1.02, 7.24)

7.40 (2.24, 13.97)

0.0211

4.70 (1.77, 14.87)

0.0018

222 (48.6)

23 (74.2)

0.006

80 (70.8)

<0.0001

E8Bg

0 (0, 0.15)

0.03 (0, 1.11)

0.0177

0 (0, 0.26)

0.0967

24 (5.3)

10 (32.3)

<0.0001

9 (7.9)

0.269

R29g

0 (0, 0.002)

0 (0, 0.43)

0.0424

0 (0, 0.24)

0.2341

13 (2.8)

5 (16.2)

<0.0001

3 (2.6)

0.913

3D7g

0 (0, 0.33)

0.01 (0, 0.37)

0.4718

0 (0, 0.42)

0.8673

36 (7.9)

4 (12.9)

0.324

10 (8.9)

0.734

  1. Significant p value in italic format
  2. aFor each antigen represented, row 1: median antibody level (interquartile range); row 2: number of seropositive children (%)
  3. bp value calculated by Mann–Whitney test or Chi squared test for antibody level or seropositivity, respectively
  4. cMerozoite surface protein 1
  5. dMerozoite surface protein 2
  6. eErythrocyte binding antigen 175
  7. fReticulocyte binding protein homologue 2A
  8. gVariant surface antigen antibody responses