{ "background": "Public health surveillance is a cornerstone of effective disease control, yet the methodological rigour and economic efficiency of such systems in resource-limited settings remain inadequately characterised. In Tanzania, a nation facing a high burden of infectious diseases, understanding the evaluation frameworks and forecasting the cost-effectiveness of surveillance investments is critical for sustainable health policy.", "purpose and objectives": "This systematic review aims to critically appraise methodological approaches used to evaluate public health surveillance systems in Tanzania and to synthesise evidence for forecasting their cost-effectiveness using time-series modelling.", "methodology": "A systematic search of multiple electronic databases was conducted following PRISMA guidelines. Studies were included if they reported on the evaluation or economic assessment of public health surveillance systems within the national context. Data were extracted and synthesised narratively. The forecasting model for cost-effectiveness analysis is specified as $CEt = \\frac{\\Delta CASESt \\times \\beta}{COSTt} + \\epsilont$, where $CEt$ is the cost-effectiveness ratio at time $t$, $\\Delta CASESt$ is the change in averted cases, $\\beta$ is a composite health utility parameter, and $COST_t$ represents total system costs. Uncertainty was quantified using 95% confidence intervals derived from Monte Carlo simulation.", "findings": "The review identified a predominant focus on the evaluation of system attributes like timeliness and completeness, with 60% of included studies employing the CDC guidelines framework. A key theme was the consistent under-reporting of operational costs, which severely limits economic analysis. The forecasting exercise indicated that integrated, multi-disease surveillance platforms are likely to be more cost-effective, with an incremental cost-effectiveness ratio (ICER) estimated at $150–$450 per disability-adjusted life year (DALY) averted, though with wide confidence intervals reflecting data paucity.", "conclusion": "Methodological evaluations of surveillance systems in Tanzania are largely descriptive and lack standardised economic components. Forecasted cost-effectiveness of integrated systems appears favourable but