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Table 2 Temporal change in antibody titers among the three groups of children

From: Multiple clinical episodes of Plasmodium falciparum malaria in a low transmission intensity setting: exposure versus immunity

Antigen Group of children Coefficient (95% CI)
   Unadjusted Adjusted a Adjusted b Adjusted c
MSP-119 Malaria-free Reference group - - -
  Single-episode −2.00 (−11.27 – 7.27) −2.68 (−12.03 – 6.74) −1.93 (−10.32 – 6.46) −2.58 (−11.10 – 5.93)
  Multiple-episodes −2.54 (−11.37 – 6.28) −2.54 (−12.91 – 5.59) −3.82 (−11.85 – 4.20) −4.93 (−13.34 – 3.49)
  Single-episode versus Multiple-episodes 0.54 (−5.88 – 6.96) 0.99 (−5.52 – 7.50) 1.89 (−4.02 – 7.80) 2.35 (−4.02 – 7.80)
MSP-2_Dd2 Malaria-free Reference group - - -
  Single-episode 0.43 (−5.01 - 5.86) 0.29 (−5.27 - 5.864) 0.24 (−4.28 - 5.66) 0.19 (−5.17 - 5.55)
  Multiple-episodes 1.90 (−3.01 – 7.35) 1.90 (−3.55 – 7.36) 1.33 (−3.69 – 6.36) 0.94 (−4.34 – 6.23)
  Single-episode versus Multiple-episodes −1.74 (−5.53– 2.06) −1.62 (−5.50– 2.26) −0.93 (−4.65– 2.79) −0.75 (−4.55– 3.05)
MSP-2_CH150/9 Malaria-free Reference group    
  Single-episode 0.24 (−9.37 - 9.86) 0.35 (−10.21 - 9.50) 0.41 (−8.77 - 9.59) 0.34 (−9.72 - 9.05)
  Multiple-episodes 6.75 (−2.39 – 15.89) 5.83 (−3.87– 15.53) 3.87 (−4.91– 12.66) 2.68 (−6.62– 11.99)
  Single-episode versus Multiple-episodes −6.51 (−13.00– 0.02) −6.18 (−12.79– 0.43) −3.46 (−12.79– 0.43) −3.02 (−9.47– 3.42)
MSP-3_3D7 Malaria-free Reference group - - -
  Single-episode −2.42 (−7.17 - 2.31) −2.23 (−7.10- 2.63) −2.37 (−7.04- 2.30) −2.37 (−7.03- 2.55)
  Multiple-episodes −0.50 (−5.02 – 4.02) −0.20 (−4.98 – 4.57) −1.20 (−5.67 – 3.26) −0.99 (−5.72 – 3.72)
  Single-episode versus Multiple-episodes −1.93 (−5.24 – 1.38) −2.03 (−5.43 – 1.37) −1.17 (−4.48 – 2.15) −1.24 (−4.64 – 2.17)
AMA-1_FVO Malaria-free Reference group - - -
  Single-episode −3.71 (−12.55 - 5.14) −4.32 (−13.32 – 4.68) −3.64 (−12.48 – 5.20) −3.76 (−13.24 – 4.72)
  Multiple-episodes 3.87 (−5.54 – 12.30) 2.87 (−5.97 – 11.71) 3.10 (−5.35 – 11.56) 3.10 (−6.82– 10.94)
  Single-episode versus Multiple-episodes −7.59 (−13.71 – -1.47)* −7.19 (−13.40 – -0.98)* −6.75 (−12.97 – -0.52)* −6.32 (−12.64 – -0.01)*
AMA-1_3D7 Malaria-free Reference group    
  Single-episode −2.83 (−10.37 - 4.71) −3.43 (−11.09 - 4.23) −2.79 (−10.30 - 4.72) −3.37 (−10.99 - 4.25)
  Multiple-episodes 3.17 (−4.02 – 10.35) 2.17 (−5.36 – 9.70) 2.83 (−4.34 – 10.01) 1.85 (−5.68 – 9.38)
  Single-episode versus Multiple-episodes −5.99 (−11.22 – 0.77)* −5.60 (−10.90 – -0.31)* −5.63 (−10.92 – -0.33)* −5.22 (−10.60 – 1.52)
PfRh2 Malaria-free Reference group - - -
  Single-episode −5.50 (−13.21 - 2.27) −5.79 (−13.71 - 2.12) −5.42 (−13.22 - 2.38) −5.77 (−13.74 - 2.19)
  Multiple-episodes −1.72 (−9.09 – 5.64) −2.25 (−10.03 – 5.54) −1.99 (−9.44 – 5.48) −2.57 (−10.46 – 5.32)
  Single-episode versus Multiple-episodes −3.74 (−9.03 – 1.54) −3.55 (−8.92 – 1.83) −3.44 (−8.86 – 1.99) −3.21 (−8.73 – 2.32)
  1. aAdjusted for sickle cell trait (hemoglobin AS). bAdjusted for whether a child was parasitemic or aparasitemic by microscopy at each of the six cross-sectional surveys. cAdjusted for sickle cell trait and whether a child was parasitemic or aparasitemic by microscopy at each of the six cross-sectional surveys. The coefficients indicate differences in the rates of change of antibody titers comparing the single- and multiple-episodes groups to the malaria-free group. Antibodies to AMA1_FVO increased significantly over five years when comparing the multiple- to the single-episode group. For all other antigens, the rates of change in antibody titers were not significant during this period. CI, confidence interval. *P < 0.05.