Sergeant Esg, Happold J, Langstaff I
AusVet Pty Ltd, Bruce, Australia Capital Territory, Australia.
Australian Government Department of Agriculture and Water Resources, Canberra, Australia Capital Territory, Australia.
Aust Vet J. 2017 Dec;95(12):474-479. doi: 10.1111/avj.12648.
Australia declared freedom from bovine tuberculosis (TB) in accordance with international guidelines in 1997 and has since maintained ongoing surveillance for this disease, primarily through abattoir surveillance of cattle carcases (meat inspection) for TB-like granulomas. The objectives of this study were to estimate the sensitivity of Australia's surveillance system and quantify the probability that Australia is free from bovine TB at the specified design prevalence.
The analysis included approximately 80 million records of individual cattle slaughtered and meat inspected at Australian abattoirs between 2005 and 2015 calendar years. Animals were identified and aggregated by property of birth within year. Herd- and population-level sensitivities and probability of freedom were estimated on an annual basis using a simulation model to account for uncertainty about the unit sensitivity of the meat inspection process.
The estimated median population sensitivity of Australia's TB surveillance system varied from a high of 80%, in years when traditional meat inspection was used, to as low as 50% after the introduction of visual-only meat inspection, for a design prevalence of 0.01% (19 herds) of Australian breeding cattle herds and 0.5% of animals within infected herds. The level of confidence in Australia's freedom from bovine TB was >95% after the first year of the analysis and >99.5% from 2007 through to the end of the analysis period in 2015. Reducing the animal-level or herd-level design prevalence, or the estimated sensitivity of meat inspection, reduced system sensitivity but confidence of disease freedom remained high.
The results demonstrated a very high level of confidence that Australia's cattle herd is truly free from bovine TB. Meat inspection for granulomas in the head and thorax of slaughtered cattle underpins this result by providing surveillance data on an extremely large number of animals each year.
澳大利亚于1997年根据国际准则宣布消灭牛结核病，并自此持续对该病进行监测，主要通过对牛尸体进行屠宰场监测（肉类检验）以检查是否存在类似结核病的肉芽肿。本研究的目的是估计澳大利亚监测系统的敏感性，并量化在指定设计流行率下澳大利亚无牛结核病的概率。
分析包括2005年至2015年历年在澳大利亚屠宰场屠宰和检验的约8000万头个体牛的记录。按年份内的出生属性对动物进行识别和汇总。每年使用模拟模型估计畜群和种群水平的敏感性以及无病概率，以考虑肉类检验过程单位敏感性的不确定性。
对于澳大利亚种牛群0.01%（19个畜群）和感染畜群内0.5%的动物的设计流行率，澳大利亚结核病监测系统估计的种群敏感性中位数从使用传统肉类检验时的80%高位，到仅采用目视肉类检验后的低至50%不等。分析第一年之后，对澳大利亚无牛结核病的信心水平>95%，从2007年到2015年分析期结束时>99.5%。降低动物水平或畜群水平的设计流行率，或肉类检验的估计敏感性，会降低系统敏感性，但无病信心仍然很高。
结果表明对澳大利亚牛群真正无牛结核病有非常高的信心水平。对屠宰牛头部和胸部的肉芽肿进行肉类检验，通过每年提供大量动物的监测数据，支撑了这一结果。
