Table 3.
Summary of studies evaluating DBS for malaria (malaria NAAT assays)
| Country | Ref. | Sample size/filter paper | Assay | Pf | Po | Pv | Pm | Unknown | Sensitivity (%) | Specificity (%) | Reference test | Notes |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Thailand | 162 | 56 samples/ Whatman 903 | In-house | ✓ | 94.6 | NR | Thin/thick blood smear | |||||
| Malaysia | 163 | 166 patients/ Whatman 3MM | In-house (adjusted) | ✓ | ✓ | 97.4 | NR | Thick blood smear | ||||
| Malaysia | 164 | 129 patients/ Whatman 3MM | In-house | ✓ | ✓ | ✓ | ✓ | NR | NR | Limit of detection: 6 parasites/μL. | ||
| Singapore | 165 | 52 patients/ Whatman No.1 | In-house | ✓ | ✓ | 100 | 100 | Thin/thick blood smear | Limit of detection: 4 parasites/μL. | |||
| Malaysia, Myanmar, Thailand | 166 | 81 patients/ Isocode cards | In-house | ✓ | ✓ | ✓ | 94.1 (Pf); 100 (Pv) | 100 (Pf); 99.1 (Pv) | Thin/thick blood smear | 1 of 1 Po samples detected. | ||
| Thailand | 58 | 136 patients/ Whatman 3MM | Multiplex PCR | ✓ | ✓ | 100 (Pf); 92.7 (Pv) | 100 (Pf); 100 (Pv) | Consensus of three PCR assays | Specificity of all three assays lower (93.8–97%) compared with microscopy. Microscopy had 90.7–92.5% sensitivity and 91.5–100% specificity. | |||
| Nested PCR | ✓ | ✓ | 100 (Pf); 100 (Pv) | 99 (Pf); 100 (Pv) | ||||||||
| RT-PCR | ✓ | ✓ | 100 (Pf); 100 (Pv) | 100 (Pf); 100 (Pv) | ||||||||
| Saudi Arabia | 55 | 118 patients/ Whatman paper | In-house | ✓ | 73 | NR | Thin/thick blood smear | Several microscopy-negative samples were positive on DBS PCR. | ||||
| Thailand, Zimbabwe | 141 | 156 patients/ FTA card | In-house | ✓ | 97.8 | 100 | Thin/thick blood smear | Limit of detection: 10 copies/reaction. | ||||
| Iran | 56 | 75 patients/ DNA Banking Card | In-house | ✓ | ✓ | 97 | 100 | Thin/thick blood smear | Whole blood was more sensitive but less specific than DBS compared with microscopy (100% sensitivity, 95.2% specificity). | |||
| Kenya | 57 | 356 patients/ Whatman 3MM | In-house | ✓ | 100 | 79 | Thin/thick blood smear | Low specificity potentially caused by insufficient microscopy expertise.57 |
Pf = Plasmodium falciparum; Pm = P. malariae; Po = P. ovale; Pv = P. vivax; RT-PCR = real time PCR; NR = not reported.