Mori Jameson J, Rivera Nelda A, Brown William M, Skinner Daniel J, Schlichting Peter E, Novakofski Jan E, Mateus-Pinilla Nohra E
Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, Champaign, IL, USA.
Illinois Department of Natural Resources, Division of Wildlife Resources, Springfield, IL, USA.
Prion. 2025 Dec;19(1):28-35. doi: 10.1080/19336896.2025.2530534. Epub 2025 Jul 10.
Chronic wasting disease (CWD) is a fatal, neurodegenerative disease of cervids, and its management heavily relies on diagnostic testing. Test results are commonly used to calculate 'apparent prevalence' (AP) - the percent of animals tested for CWD (CWD tests) with CWD-positive test results (CWD cases) - but this obscures how tests and cases individually contribute to this statistic. This is most relevant when CWD testing is limited because when few animals are tested, detection of even a single infected deer can result in a high AP that poorly reflects reality. We hypothesized that when CWD testing is limited, AP is negatively driven by testing - rather than cases - with more tests corresponding to lower APs. Graphed CWD surveillance data from townships in Illinois and Wisconsin, USA, indicate that CWD AP values ≥50% were only observed when <23 deer were tested. We used Bayesian multilevel zero-inflated Beta regression to model AP as a function of CWD tests, CWD cases and nonlinear transformations of these two terms separately for each state. The best-fit models of both identified a statistically significant negative relationship between AP and testing numbers that was modified by a positive nonlinear test covariate. This means adding tests when testing is low can have a big impact on decreasing the AP, but this relationship weakens as testing increases. We urge treating apparent prevalences ≥50% with caution and emphasize the importance of increasing the test results when initial surveillance has yielded <23 tests.
慢性消耗病（CWD）是一种致命的鹿科动物神经退行性疾病，其管理在很大程度上依赖于诊断检测。检测结果通常用于计算“表观患病率”（AP）——即接受CWD检测（CWD检测）且检测结果为CWD阳性（CWD病例）的动物百分比——但这掩盖了检测和病例对这一统计数据的单独贡献。当CWD检测有限时，这一点最为相关，因为当检测的动物很少时，即使检测到一只受感染的鹿也可能导致高AP，而这并不能很好地反映实际情况。我们假设，当CWD检测有限时，AP受检测而非病例的负面影响，检测次数越多，AP越低。对美国伊利诺伊州和威斯康星州各城镇的CWD监测数据进行绘图分析表明，只有在检测的鹿少于23只时，才观察到CWD的AP值≥50%。我们使用贝叶斯多级零膨胀贝塔回归，分别针对每个州，将AP建模为CWD检测次数、CWD病例数以及这两个变量的非线性变换的函数。两个州的最佳拟合模型均确定了AP与检测次数之间存在统计学上显著的负相关关系，且这种关系会因一个正的非线性检测协变量而改变。这意味着在检测次数较少时增加检测对降低AP有很大影响，但随着检测次数增加，这种关系会减弱。我们敦促谨慎对待≥50%的表观患病率，并强调在初始监测的检测次数＜23次时增加检测结果的重要性。
