Table 1. ALI as a potential reservoir for transmission in the Indian subcontinent.
| Reference | Bangladesh | India | Nepal | |
|---|---|---|---|---|
| Prevalence of ALI | ||||
| - rk39 ICT | [50,58–62] | 0.25% | 5.6–13.8% | |
| - rk39 ELISA | [41,42,44,47,49,63,64] | 10–14% | 5.4–26.3% | 6.4–12.6% |
| - DAT | [41,42,44,50,51,54,56,61–63,65–72] | 3.02% | 3.1–26.4% | 4.4–16.2% |
| - LST | [47,54,73,74] | 19–35% | 19–23.1% | 13.2% |
| - PCR | [42,53,58,62,65,71,75,76] | 7.2–36.9% | 5.1–17.9% | |
| Prevalence among healthy contacts of current or past VL cases | ||||
| - rk39 ICT | [60] | 0.08% | ||
| - rk39 ELISA | [42,77] | 19.5–43.6% | ||
| - DAT | [42,65,66,69] | 14.4–100% | 20.8% | |
| - IFAT | [78] | 17.5% | ||
| - LST | [78] | 5% | ||
| - PCR | [42,65] | 20.6% | 12.5% | |
| Incidence (1y) | ||||
| - rk39 ICT | [60] | 0% (6mo) | ||
| - rk39 ELISA | [41,44,46,47] | 6.31% | 1.3–27.3% | |
| - DAT | [41,44,46,48,55,72] | 2.5–27.3% | 2.9–7.2% | |
| - qPCR (parasite/ml) | [46] | 34.8% (>0); 3.8% (>1p/ml); 1.36% (>5p/ml); | ||
| -rKRP42 ELISA (at 30mo) | [79] | 23.4% | ||
| ALI to VL ratio | [47,48] | 4:1 | 7.6:1 | 9.6:1 |
| Risk factors for ALI | ||||
| - contact of VL (cf non-contact of VL) OR | [47,50–52,57,65] | 1.37–1.85 | 1.25–3.71 | 1.66–5.5 |
| - presence of other seropositive or sero-converter in house OR | [52] | 1.37–2.22 | 1.37–2.22 | |
| - family size OR | [54] | 4.4 | ||
| - damp floor OR | [55] | 2.4 | ||
| - mud walls OR | [54,55] | 28.9 | 4.3 | 3.0 |
| - proximity to pond OR | [54,55] | 2.1 | 3.7 | |
| - proximity to forest OR | [57] | 3.67 | ||
| - livestock ownership OR | [54–56] | 1.16–2.1 | 0.4–1.0 | |
| - cattle density OR | [47,51] | 0.97 | 0.63 | |
| - spatial clustering of PCR+ human with PCR+ animals | [53] | significant | ||
| - Risk of spatial clustering of PCR+ or sero+ human for transmission | [49,53] | High risk | No effect | |
| - sleeping covered/inside OR | [55] | 0.5–0.6 | ||
| - age OR | [41,47,51,52,54,56] | 1.12 | 1.57–3.68 | 1.57–7.29 |
| - highest (cf lowest) SES OR | [52] | 0.63 | 0.63 | |
| - poverty OR | [51] | 3.86 | ||
| - indoor residual spraying OR | [55] | No effect | ||
| - IRS more than 18mo ago OR | [52] | 1.53 | 1.53 | |
| - use of bednet OR | [47,52,55] | No effect– 0.82 (ns) | 0.7–1.09 (ns) | 0.66 (ns) |
| Proportion asymptomatic with spontaneous resolution at 1y | ||||
| - rk39 ELISA | [41,47,62] | 50.21% | 59–60% | |
| - DAT | [41,48,62,66] | 33–86.7% | 86.7% | |
| Progression of ALI to VL within 1y | ||||
| - rk39 ICT | [58,62] | 12.5–23.1% | ||
| - rk39 ELISA | [44,47,49] | 5.4–25% (6mo– 2y) | 1.8–23.3% | 7.7% |
| - DAT | [44,48,50,68] | 5.4% (2y) | 1.5–16.6% | 1.681 – 9.8% |
| - PCR | [46,58] | 2.5–17.9% | ||
| -rKRP42 ELISA | [79] | 29.2% | ||
| - Contacts of VL case | [58,66,77] | 24.1–69.1% | ||
| - Contacts of active VL case | [66] | 18.8% | ||
| - Contacts of cured VL case | [66] | 30.8% | ||
| - Non-contacts | [58,66] | 5–38% | ||
| Risk factors for progression of ALI to VL | ||||
| - contact of VL (cf non-contact) OR | [47,62,66] | 2.85 | 3.36–4.82 | |
| - contact of cured VL (cf contact of active VL) OR | [66] | 1.64 | ||
| - Risk of spatial clustering of PCR+ or sero+ for progression to VL | [49] | Highest risk | ||
| - age (10y increment) OR | [47] | 0.74 | ||
| - beef, goat consumption OR | [47] | 0.49 | ||
| Biomarkers for progression of ALI to VL | ||||
| - rk39 titres HR | [44,80] | |||
| Negative | reference | reference | reference | |
| Mod positive | 1.6 | 1.6–4.9 | -- | |
| Strongly positive | 17.7 | 7.7–39.6 | 26.9 | |
| - rk39 titres among contacts of VL (positive predictive value) | [77] | 44% at 3mo, 56.6% at 6mo; | ||
| - rk39 / DAT titres high | [46] | 60% | ||
| - Sero-converters rk39 titres HR | [44,80] | |||
| Negative | reference | reference | ||
| Mod positive | 4.7 | 0.9 (ns) | ||
| Strongly positive | 165 | 15.9–123.9 | ||
| - DAT titres HR | [44] | |||
| <1:1600 | reference | reference | ||
| 1600 - <25600 | 1.0–3.8 | -- | ||
| >1:25600 | 7.9–26.6 | 35.6 | ||
| - Sero-converters DAT titres HR | [44] | |||
| <1:1600 | reference | reference | ||
| 1600 - <25600 | 6.6–9.0 | 10.1 | ||
| >1:25600 | 44.5–111.0 | 99.2 | ||
| DAT+ve (cf DAT-ve) RR at 1y | [48] | 3.42 | 3.42 | |
| Recent DAT sero-converter (cf EHC) RR at 1y | [48] | 11.5 | 11.5 | |
| Immune and other markers | ||||
| - IFN- γ, NO, CRP | [47,81] | Raised | Raised | |
| - TNF –α, IL-2, IL-4 | [81] | Low | ||
| - Serum retinol, zinc | [47] | Low | ||
| Parasite markers | ||||
| - parasite load (>5genome equivalent/mL) | [46,76] | 80% | ||
1: at 6mo follow up
Note: cf (compared from); CRP (C-reactive protein); DAT (Direct agglutination test); EHC (Endemic healthy controls); ELISA (Enzyme linked immunosorbent assay); HR (Hazard ratio); IFN- γ (Interferon gamma); IL-2 (Interleukin 2), IL-4 (Interleukin 4); LST (Leishmanin skin test); NO (Nitric oxides); OR (Odds ratio); PCR (Polymerase chain reaction); qPCR (quantitative polymerase chain reaction); rk39 (recombinant kinetoplast 39); RR (Relative risk); TNF –α (Tumor necrosis factor alpha)