From: Stochastic agent-based modeling of tuberculosis in Canadian Indigenous communities
Parameter | Details | Value | Source |
---|---|---|---|
Tuberculosis Natural History Parameters | |||
Probability of transmission (per contact) | Â | 0.1 | Abu-Raddad [12] |
Number of respiratory contacts (per year) |  | 40–1000 | Estimated by model calibration |
Proportion of transmission occurring in community | Varied | 0.01–0.15 | Assumption |
Proportion of new infections entering latent fast state (active disease in <5 years) | Â | Â | Abu-Raddad [12] |
 | Adult | 0.15 |  |
 | Child | 0.05 |  |
Progression to active disease (per year) | Fast progressor | 1.5 | Abu-Raddad [12] |
Progression to active disease (lifetime probability, rate dependent on age at infection) | Slow progressor | 0.05 | Abu-Raddad [12] |
Proportion of active cases with extrapulmonary disease | Â | Â | Kivalliq surveillance data |
 | Adult | 0.11 |  |
 | Child | 0.042 |  |
Proportion of active cases with high transmissibility pulmonary disease | Â | Â | Kivalliq surveillance data |
 | Adult | 0.3 |  |
 | Child | 0.043 |  |
Proportion of active cases with low transmissibility pulmonary disease | Â | Â | Kivalliq surveillance data |
 | Adult | 0.59 |  |
 | Child | 0.915 |  |
Infectivity (relative to high transmissibility TB) | Â | Â | Abu-Raddad [12] |
 | Low transmissibility TB | 0.25 |  |
 | Extrapulmonary TB | 0 |  |
Spontaneous recovery rate (per year) | Â | 0.1 | Abu-Raddad [12] |
Relative susceptibility to re-infection | Resusceptible individuals | 0.6 | Vynnycky [33] |
Probability of TB-attributable mortality with active disease | Â | 0.0094 | Kivalliq surveillance data |
Population and Community Characteristics | |||
Number of communities | Â | 7 | Census [18] |
Initial number of households | Â | 1890 | Census [19] |
Average household size | Â | 4 | Census [18] |
Number of new households added (per year) | Â | 30 | Census [18] |
Proportion of population <15 years of age | Â | 0.35 | Census [18] |
Initial number of individuals diagnosed and on treatment | Â | 2 | Kivalliq surveillance data |
Initial number of individuals in different states (remaining are susceptible) | Â | Â | Estimated by model calibration |
 | Undiagnosed LTBI | 10–2000 |  |
 | Undiagnosed active TB disease | 1–50 |  |
 | Resusceptible (following treatment or spontaneous recovery) | 50–3000 |  |
Birth rate (per year) | Females aged 15–44 | 0.1 | Nunavut Bureau of Statistics [21] |
Mortality rate | Age-specific, estimated from Nunavut life tables | Â | Statistics Canada [20] |
Screening and Treatment Parameters | |||
Time to diagnosis for active TB disease | Â | Â | Tian [27] |
 | High | 0.5 |  |
 | Low | 0.64 |  |
 | Extrapulmonary | 0.64 |  |
Time in treatment (years) | Active TB disease | 0.6 | Kivalliq surveillance data |
Probability lost to follow-up while on treatment for active TB disease | Â | Â | Kivalliq surveillance data |
 | Adult | 0.06 |  |
 | Child | 0.04 |  |
Passive population screening for LTBI (per year) | Â | 0.004 | TAIMA TB report [34] |
Average time to LTBI treatment initiation for cases identified by population screening (months) | Â | 1 | Assumption |
Average time to completion of contact tracing (months) | Â | 2 | Tian [13] |
Time on treatment for LTBI (years) | Â | 0.75 | Canadian TB Standards [24] |
Probability LTBI treatment is completed | Â | 0.7 | Alvarez [5] |