Table 1.
Summary of the evaluation results of the SsRapid™ dipstick test using serum samples from a Strongyloides endemic area in northeast Thailand
| Group | Assessed, n | SsRapid™ reactivity | Sensitivity (%) | Specificity (%) | |
|---|---|---|---|---|---|
| Positive | Negative | ||||
| Group 1 Positive S. stercoralis | 100 | 82 | 18 | ||
| 1.1 Positive S. stercoralis larvae and antibody | 84 | 69 | 15 | 69/84 (82) | |
| 1.2 Positive S. stercoralis antibody | 16 | 13 | 3 | ||
| Group 2 Negative in endemic areas | 25 | 6 | 19 | ||
| Group 3 Other parasites | 25 | 1 | 24 | 24/25 (96) | |
| Echinostoma sp. | 1 | 0 | 1 | ||
| Hookworm | 9 | 1 | 8 | ||
| Minute intestinal fluke | 1 | 0 | 1 | ||
| Opisthorchis viverrini | 7 | 0 | 7 | ||
| Taenia sp. | 1 | 0 | 1 | ||
| Minute intestinal fluke + hookworm | 1 | 0 | 1 | ||
| O. viverrini + hookworm | 1 | 0 | 1 | ||
| O. viverrini + minute intestinal fluke | 1 | 0 | 1 | ||
| O. viverrini + Taenia sp. | 2 | 0 | 2 | ||
| O. viverrini + minute intestinal fluke + Echinostoma sp. | 1 | 0 | 1 | ||
Group 1: Positive for S. larvae and/or antibody (S. ratti ELISA). Cutoff: 132 units.
Group 2: Negative for S. stercoralis antibody and fecal examination. This group resides in endemic areas.
Group 3: Positive for other parasites according to the fecal examination (formalin-ethyl acetate concentration technique) results.
The positive and negative predictive values of the SsRapid are 98.6% and 61.5%, respectively, and the accuracy is 85.3%. The receiver-operating characteristic curve shows an area under the curve of 0.8303 to 0.9631 (P < 0.0001) (Supplemental Figure S5).