Table 3.
P. falciparum specific immune responses in parasite free individuals and individuals with sub-microscopic parasite densities by 18S QT-NASBA
| Parasite free individuals | Sub-microscopic parasite carriers | p-value | |
|---|---|---|---|
| MSP-1 IgG antibodies | |||
| prevalence, % (n/N) | 68.0 (183/269) | 76.7 (89/116) | 0.086 |
| median level (IQR) | 0.26 (0.14 – 0.79) | 0.33 (0.18 – 1.17) | 0.042 |
| MSP-2 IgG antibodies | |||
| prevalence, % (n/N) | 53.4 (134/251) | 58.9 (66/112) | 0.33 |
| median level (IQR) | 0.32 (0.13 – 0.59) | 0.41 (0.19 – 0.72) | 0.034 |
| AMA-1 IgG antibodies | |||
| prevalence, % (n/N) | 61.0 (153/251) | 65.2 (73/122) | 0.44 |
| median level (IQR) | 0.34 (0.17 – 0.99) | 0.48 (0.21 – 1.04) | 0.14 |
Parasitaemia was detected by 18S QT-NASBA and microscopically confirmed parasite carriers were excluded from this table. The optical density in the ELISA was used as indicator of antibody level. P-values are obtained by χ2-test for antibody prevalence or Wilcoxon Rank-sum test for antibody level. The cut-off values for sero-positivity (antibody prevalence) for MSP-1, MSP-2 and AMA-1 were 0.171, 0.292 and 0.252, respectively.