Table 4.
Results and characteristics of malaria stratified by group
| Study group | Patent volunteers (n) | Prepatent period (days) (range)* | Smear parasite density (μL)* | Time (hours) to first PCR (days)* | First PCR positive (para/μL)* | PCR (para/μL) at patency* |
|---|---|---|---|---|---|---|
| A: 1 × 104 PfSPZ 2 × 50 μL | 4/4† | 14.5 (13–16) | 14.7 (4–99) | 286.6 (11.9) | 0.156 | 18.3 |
| B: 1 × 104 PfSPZ 8 × 50 μL | 3/5 | 14.0 (14) | 46.3 (25–78) | 258.6 (10.8) | 0.549 | 64.4 |
| C: 1 × 104 PfSPZ 2 × 10 μL | 5/5 | 13.5 (13–14) | 8.1 (2–134) | 259.6 (10.8) | 0.210 | 17.8 |
| D: 1 × 104 PfSPZ 8 × 10 μL | 2/5 | 13.0 (13) | 10.5 (10–11) | 201 (8.4) | 0.050 | 17.2 |
| E: 5 × 104 PfSPZ 2 × 10 μL | 4/5 | 13.2 (12–15) | 10.2 (5–15) | 239.7 (10.0) | 0.161 | 24.8 |
| F: 5 × 104 PfSPZ 8 × 10 μL | 5/5 | 12.7 (12–14) | 21.4 (8–46) | 247.6 (10.3) | 0.154 | 25.6 |
| Combined groups | 23/29 | 13.5 (12–16) | 15.0 (2–134) | 256.8 (10.7) | 0.161 (0.015–6.16) | 24.5 (6.8–105) |
CHMI = controlled human malaria infection; PCR = polymerase chain reaction; PfSPZ = Plasmodium falciparum sporozoite.
*
Blood smear, time, and PCR quantity expressed as geometric mean PCR parasite density. Prepatent period is expressed as mean.
†
Denominator reflects withdrawal of volunteer after CHMI (data from two volunteers removed due to missing interval sample).