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Table 2 Performance of PCR relative to expert laboratory microscopy at different Plasmodium falciparum and Plasmodium vivax parasite densities

From: Comparison of PCR and microscopy for the detection of asymptomatic malaria in a Plasmodium falciparum/vivax endemic area in Thailand

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%)
  1. a Data for each parasite includes 4 mixed infections
  2. b A single sample was negative for P. falciparum by PCR, however, this sample was positive for P. vivax and P. malariae by PCR