Table 2.
Partial protection after CPS immunization as detected by thick smear or retrospective qPCR
| Number | Pre-patent period (days) | Parasitemia 1st peak (log) | |||||
|---|---|---|---|---|---|---|---|
| Mean | SD | P value | Mean | SD | P value | ||
| Positive thick smeara | |||||||
| CPS-immunized (partially protected)b | 10 | 12.2 | 1.85 | 0.006 | 1.00 | 0.56 | 0.02 |
| Controls (unprotected) | 9 | 9.7 | 2.05 | 2.07 | 1.07 | ||
| Positive qPCRc | |||||||
| CPS-immunized (partially protected)b | 10 | 9.6 | 2.06 | 0.035 | 1.10 | 0.67 | 0.04 |
| Controls (unprotected) | 9 | 7.9 | 1.83 | 1.99 | 1.06 | ||
Differences between mean pre-patent periods were determined by Mann–Whitney U test in ten partially protected and nine control volunteers after CPS immunization [11, 12]. Parasitaemia of the first parasite wave was estimated by determining the geometric mean parasitaemia from 6.5 to 8.0 days after challenge. Differences in the mean parasitaemia of the first peak was determined by an independent samples t test
aThreshold of 4000 parasites/ml and twice daily blood sampling
bOnly volunteers with patent parasitemia included in the analyis
cThreshold of 100 parasites/ml and once daily blood sampling