Table 1.
Operating characteristics of the mobile phone microscope compared with conventional microscopy for the diagnosis of soil-transmitted helminth infection (n = 199 Kato-Katz thick smears)
| Organism | Conventional microscope n (%) | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) |
|---|---|---|---|---|---|
| Any soil-transmitted helminth egg visualized | 173 (86.9) | 69.4 (61.8–76.0) | 61.5 (40.7–79.1) | 92.3 (85.9–96.0) | 23.2 (14.2–35.2) |
| All A. lumbricoides | 41 (20.6) | 81.0 (65.4–90.9) | 87.3 (80.7–91.9) | 63.0 (48.7–75.4) | 94.5 (89.1–97.4) |
| A. lumbricoides (light infection)* | 27 (13.6) | 74.5 (53.4–88.1) | – | – | – |
| A. lumbricoides (moderate/heavy infection)† | 15 (7.5) | 93.3 (66.0–99.7) | – | – | – |
| All T. trichiura | 158 (79.4) | 54.4 (46.3–62.3) | 63.4 (46.9–77.4) | 85.1 (76.4–91.2) | 26.5 (18.4–36.6) |
| T. trichiura (light infection)‡ | 107 (53.8) | 43.9 (34.5–53.8) | – | – | – |
| T. trichiura (moderate/heavy infection)§ | 51 (25.6) | 76.5 (62.2–86.7) | – | – | – |
| All hookworm¶ | 98 (49.2) | 14.3 (8.3–23.1) | 89.1 (81.0–94.2) | 56.0 (35.3–75.0) | 51.7 (44.1–59.3) |
CI = confidence interval; NPV = negative predictive value; PPV = positive predictive value.
*
Eggs per 1 g stool (EPG): 1–4,999.
†
EPG: ≥ 5,000.
‡
EPG: 1–999.
§
EPG: ≥ 1,000.
¶
Only WHO-defined low fecal egg counts available for analysis (1–1,999 EPG).