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

Table 3 Association between malaria episodes and antibody seroprevalence in 18 months old children

Antigen tested/parasite isolate	Seropositives^a (%)	No episode (n = 457)	Any episode within 18 months % (n = 144)	p value^b	Single episode % (n = 119)	p value^b	Multiple episodes % (n = 25)	p value^b	Unadjusted OR (95% CI)	p value^c	Adjusted OR (95% CI)	p value^d
MSP1 19 kD^e	327 (54.4)	224 (49.0)	103 (71.5)	< 0.0001	83 (69.8)	< 0.0001	20 (80.0)	0.003	2.24 (1.59, 3.17)	< 0.0001	2.21 (1.56, 3.12)	< 0.0001
MSP2^f	162 (26.9)	113 (24.7)	49 (34.0)	0.028	40 (33.6)	0.051	9 (36.0)	0.207	1.41 (1.02, 1.94)	0.034	1.38 (1.00, 1.90)	0.049
EBA175^g	69 (11.5)	50 (10.9)	19 (13.2)	0.459	13 (10.9)	0.996	6 (24.0)	0.047	1.33 (0.87, 2.05)	0.182	1.31 (0.85, 2.01)	0.216
Rh2A9^h	151 (25.1)	108 (23.6)	43 (29.9)	0.133	34 (28.6)	0.265	9 (36.0)	0.160	1.32 (0.95, 1.83)	0.095	1.30 (0.93,1.80)	0.117
Schizont	325 (54.1)	222 (48.6)	103 (71.5)	< 0.0001	85 (71.4)	< 0.0001	18 (72.0)	0.023	2.14 (1.52, 3.00)	< 0.0001	2.20 (1.55, 3.13)	< 0.0001
E8Bⁱ	43 (7.2)	24 (5.3)	19 (13.2)	0.001	17 (14.3)	0.001	2 (8.0)	0.554	1.85 (1.15, 2.98)	0.010	1.87 (1.15, 3.04)	0.011
R29ⁱ	21 (3.5)	13 (2.8)	8 (5.6)	0.122	7 (5.9)	0.107	1 (4.0)	0.738	1.55 (0.78, 3.09)	0.204	1.51 (0.75, 3.02)	0.245
3D7ⁱ	50 (8.3)	36 (7.9)	14 (9.7)	0.485	10 (8.4)	0.850	4 (16.0)	0.152	1.31 (0.80, 2.14)	0.278	1.30 (0.79, 2.14)	0.291

Significant p value in italic format
^aSamples defined as antibody positive if levels greater than mean + 3SD of negative controls
^bp value compared to children with no episode calculated by Chi squared test
^cp-value derived from logistic regression with Odds Ratios (OR) and 95% confidence intervals (CI)
^dp-value derived from multivariate logistic regression with Adjusted Odds Ratios (OR) after controlling for duration of gestation, HIV infection, gender of the child, maternal anaemia
^eMerozoite surface protein 1
^fMerozoite surface protein 2
^gErythrocyte binding antigen 175
^hReticulocyte binding protein homologue 2A
ⁱVariant surface antigen antibody responses

ISSN: 1475-2875