The effect of systematic screening of the general population on TB case notification rates.

BACKGROUND: Understanding how TB case notification rates (TB-CNR) change with TB screening and their association with underlying TB incidence/prevalence could inform how they are best used to monitor screening impact.METHODS: We undertook a systematic review to identify articles published between 1 January 1980 and 13 April 2020 on TB-CNR trends associated with TB screening in the general-population. Using a simple compartmental TB transmission model, we modelled TB-CNRs, incidence and prevalence dynamics during 5 years of screening.RESULTS: Of 27,282 articles, seven before/after studies were eligible. Two involved population-wide screening, while five used targeted screening. The data suggest screening was associated with initial increases in TB-CNRs. Increases were greatest with population-wide screening, where screening identified a large proportion of notified people with TB. Only one study reported on sustained screening; TB-CNR trends were compatible with model simulations. Model simulations always showed a peak in TB-CNRs with screening. Following the peak, TB-CNRs declined but were typically sustained above baseline during the intervention. Incidence and prevalence decreased during the intervention; the relative decline in incidence was smaller than the decline in prevalence.CONCLUSIONS: Published data on TB-CNR trends with TB screening are limited. These data are needed to identify generalisable patterns and enable method development for inferring underlying TB incidence/prevalence from TB-CNR trends.

Heterogeneity of distribution of tuberculosis in Sheka Zone, Ethiopia: drivers and temporal trends.

OBJECTIVE: To describe the distribution of tuberculosis (TB) and its drivers in Sheka Zone, a geographically remote region of Ethiopia. METHODS: We collected data on TB patients treated from 2010 to 2014 in the Sheka Zone. Predictors of TB incidence were determined using a multivariate generalised linear regression model. RESULTS: We found significant spatial autocorrelation of TB incidence by kebele (the smallest administrative geographical subdivision in Ethiopia) (Moran's I = 0.3, P < 0.001). The average TB incidence per kebele ranged from 0 to 453 per 100 000 population per year, and was significantly associated with average TB incidence across adjacent kebeles, TB incidence in the same kebele in the previous year and health facility availability. Each increment in TB incidence by 10/100 000/year in adjacent kebeles or in a previous year was associated with an increase in TB incidence of respectively 3.0 and 5.5/100 000/year. Availability of a health centre was associated with an increase in TB incidence of 84.3/100 000. CONCLUSIONS: TB incidence in rural Ethiopia is highly heterogeneous, showing significant spatial autocorrelation. Both local transmission and access to health care are likely contributors to this pattern. Identification of local hotspots may assist in developing and optimising effective prevention and control strategies.