From: Towards harmonization of microscopy methods for malaria clinical research studies

True parasite density (parasites/µL) | |||||||
---|---|---|---|---|---|---|---|

200 | 250 | 500 | 1000 | 5000 | 10,000 | 16,000 | |

(A) Thick film counts | |||||||

Against 200 WBC | |||||||

Distribution of single read (n = 1000)
| |||||||

Mean (sd) | 199.8 (89.1) | 250.8 (101.6) | 496.7 (138.9) | 983.5 (200.1) | 5018.5 (565.1) | 10,041.7 (904.6) | 16,001.9 (1357.9) |

25th and 75th percentiles | 120 and 261 | 189 and 314 | 396 and 585 | 839 and 1121 | 4619 and 5397 | 9412 and 10,624 | 15,080 and 16,956 |

5th and 95th percentiles | 76 and 355 | 82 and 429 | 272 and 731 | 673 and 1320 | 4121 and 5989 | 8610 and 11,604 | 13,822 and 18,339 |

Simulation of 2 microscopy readings (n = 10,000)
| |||||||

% with both readings ≤ 200/uL | 34.3 | 13.9 | 0.02 | 0.0 | 0.0 | 0.0 | 0.0 |

% requiring 3rd read (Obare criteria) | 12.7 | 15.4 | 15.3 | 15.4 | 23.1 | 28.7 | 36.9 |

Against 500 WBC | |||||||

Distribution of single read (n = 1000)
| |||||||

Mean (sd) | 199.7 (57.0) | 248.9 (64.5) | 499.5 (89.2) | 998.3 (133.8) | 5004.5 (354.2) | 9995.1 (579.5) | 15,964.0 (883.0) |

25th and 75th percentiles | 158 and 238 | 204 and 287 | 441 and 559 | 910 and 1085 | 4756 and 5247 | 9607 and 10,372 | 15,395 and 16,556 |

5th and 95th percentiles | 112 and 300 | 144 and 365 | 351 and 648 | 780 and 1213 | 4441 and 5605 | 9076 and 10,992 | 14,534 and 17,524 |

Simulation of 2 microscopy readings (n = 10,000)
| |||||||

% with both readings ≤ 200/µL | 25.3 | 4.9 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |

% requiring 3rd read (Obare criteria) | 1.9 | 3.0 | 2.5 | 2.8 | 5.5 | 9.8 | 16.9 |

True parasite density (parasites/µL) | |||||||
---|---|---|---|---|---|---|---|

16,000 | 20,000 | 32,000 | 64,000 | 128,000 | 200,000 | 250,000 | |

(B) Thin film counts | |||||||

Against 1000 RBC | |||||||

Distribution of single read (n = 1000)
| |||||||

Mean (sd) | 16,328.4 (8892.7) | 19,979.2 (9541.3) | 32,539.0 (12,592.1) | 63,489.3 (17,600.1) | 127,011.1 (23,853.1) | 200,712.7 (32,038.7) | 252,236.6 (33,445.7) |

25th and 75th %iles | 9609 and 22,386 | 13,915 and 24,919 | 23,747 and 39,969 | 51,450 and 75,794 | 110,391 and 142,273 | 179,076 and 221,459 | 229,845 and 274,556 |

5th and 95th %iles | 4617 and 33,049 | 4818 and 37,912 | 14,020 and 53,447 | 34,967 and 93,502 | 89,799 and 168,045 | 147,499 and 254,466 | 194,879 and 306,865 |

Simulation of 2 microscopy readings (n = 10,000)
| |||||||

% requiring 3rd read (Obare criteria) | 11.5 | 12.1 | 13.6 | 14.5 | 11.9 | 14.5 | 10.6 |

Against 2000 RBC | |||||||

Distribution of single read (n = 1000)
| |||||||

Mean (sd) | 16,116.9 (6051.3) | 20,140.1 (6869.9) | 3773.0 (9055.7) | 64,819.4 (12,493.7) | 128,216.7 (17,857.2) | 199,747.5 (22,125.0) | 249,103.6 (25,238.4) |

25th and 75th %iles | 11,872 and 19,666 | 15,956 and 24,070 | 25,668 and 37,926 | 56,610 and 72,317 | 115,908 and 140,332 | 183,871 and 215,118 | 231,741 and 265,957 |

5th and 95th %iles | 7076 and 26,527 | 9397 and 31,699 | 18,248 and 47,561 | 45,282 and 86,739 | 99,791 and 159,231 | 164,356 and 235,178 | 209,136 and 291,824 |

Simulation of 2 microscopy readings (n = 10,000)
| |||||||

% requiring 3rd read (Obare criteria) | 2.5 | 3.1 | 4.6 | 3.7 | 3.5 | 3.3 | 3.5 |