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

Josea Rono; Anna Färnert; Linda Murungi; John Ojal; Gathoni Kamuyu; Fatuma Guleid; George Nyangweso; Juliana Wambua; Barnes Kitsao; Ally Olotu; Kevin Marsh; Faith HA Osier

doi:10.1186/s12916-015-0354-z

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)

^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.

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