Table 3.
Association of anti-erythrocyte surface antibodies and parasitaemia with protection from clinical malaria
| Groupa |
||||
|---|---|---|---|---|
| ab+ pf+ | ab+ pf− | ab− pf+ | ab− pf− | |
| Responses against A4U | ||||
| n | 84 | 65 | 33 | 90 |
| % with malariab | 22.62 | 20 | 54.5 | 15.6 |
| OR (95% CI)c | 1.67 (0.60–4.63) | 1.35 (0.48–3.78) | 3.78 (1.21–11.8) | 1 |
| P-value | 0.325 | 0.567 | 0.022 | na |
| Responses against A4 40-cycle | ||||
| n | 39 | 22 | 16 | 63 |
| % with malariab | 30.8 | 45.5 | 62.5 | 23.8 |
| OR (95% CI)c | 1.55 (0.55–4.34) | 2.88 (0.94–8.82) | 5.35 (1.66–17.2) | 1 |
| P-value | 0.402 | 0.064 | 0.005 | na |
| Responses against 3D7 | ||||
| n | 42 | 31 | 13 | 54 |
| % with malariab | 30.9 | 38.7 | 69.2 | 24.1 |
| OR (95% CI)c | 1.43 (0.53-3.91) | 2.01 (0.74-5.47) | 7.10 (1.87-26.9) | 1 |
| P-value | 0.479 | 0.170 | 0.004 | na |
| Responses against P1 (clinical isolate) | ||||
| n | 20 | 11 | 35 | 74 |
| % with malariab | 30 | 54.5 | 45.7 | 25.7 |
| OR (95% CI)c | 1.38 (0.42–5.97) | 3.72 (0.98–14.1) | 2.53 (1.07–5.97) | 1 |
| P-value | 0.587 | 0.053 | 0.035 | na |
Individuals were stratified according to whether they were antibody-positive (ab+), scored as corrected mean fluorescence intensity (MFI) greater than the mean plus 3 SD of the MFI of 20 non-exposed donors, or negative (ab−) and parasite-positive (pf+) or -negative (pf−) (detected by microscopy) at the time of the cross-sectional survey.
Malaria defined as at least one episode of fever >37.5 °C plus parasitaemia >2500/μl if aged greater than 1 year and fever >37.5 °C plus any parasitaemia if aged less than 1 year.
Odds ratio (OR) of becoming a subsequent case of malaria during the 6 month follow-up, obtained from a multiple logistic regression controlling for age (categorised as a factor of 6 month duration) and exposure (estimated from responses to whole schizont extract) and excluding the first 30 days of follow-up.