Table 2 Performance of PCR relative to expert laboratory microscopy at different Plasmodium falciparum and Plasmodium vivax parasite densities
Parasites/μl | P. falciparum | P. vivax | ||
|---|---|---|---|---|
No. detected by microscopya | No. positive by PCR (%) | No. detected by microscopya | No. positive by PCR (%) | |
>10,000 | 10 | 10 (100.0%) | 3 | 3 (100.0%) |
5,000–9,999 | 4 | 4 (100.0%) | 1 | 1 (100.0%) |
1,000–4,999 | 22 | 21 (95.5%) | 11 | 11 (100.0%) |
500–999 | 11 | 10 (90.9%) b | 5 | 5 (100.0%) |
250–499 | 17 | 14 (82.4%) | 19 | 15 (78.9%) |
100–249 | 87 | 29 (33.3%) | 57 | 34 (59.6%) |
1–<99 | 118 | 24 (20.3%) | 294 | 71 (24.1%) |
Negative | 8,321 | 96 (1.2%) | 8,200 | 251 (3.1%) |
Total | 8,590 | 208 (2.4%) | 8,590 | 391 (4.6%) |