Dekker Aldo, van Roermund Herman J W, Hagenaars Thomas J, Eblé Phaedra L, de Jong Mart C M
Wageningen Bioveterinary Research, Lelystad, Netherlands.
Department of Quantitative Veterinary Epidemiology, Wageningen University, Wageningen, Netherlands.
Front Vet Sci. 2020 Nov 20;7:540433. doi: 10.3389/fvets.2020.540433. eCollection 2020.
Quantitative understanding of transmission with and without control measures is important for the control of infectious diseases because it helps to determine which of these measures (or combinations thereof) will be effective to reduce transmission. In this paper, the statistical methods used to estimate transmission parameters are explained. To show how these methods can be used we reviewed literature for papers describing foot-and-mouth disease virus (FMDV) transmission in pigs and we used the data to estimate transmission parameters. The analysis showed that FMDV transmits very well when pigs have direct contact. Transmission, however, is reduced when a physical barrier separates infected and susceptible non-vaccinated pigs. Vaccination of pigs can prevent infection when virus is administered by a single intradermal virus injection in the bulb of the heel, but it cannot prevent infection when pigs are directly exposed to either non-vaccinated or vaccinated FMDV infected pigs. Physical separation combined with vaccination is observed to block transmission. Vaccination and separation can make a significant difference in the estimated number of new infections per day. Experimental transmission studies show that the combined effect of vaccination and physical separation can significantly reduce transmission (R < 1), which is a very relevant result for the control of between-farm transmission.
对有无控制措施情况下的传播进行定量理解，对于传染病控制至关重要，因为这有助于确定哪些措施（或其组合）能有效减少传播。本文解释了用于估计传播参数的统计方法。为展示这些方法的使用方式，我们查阅了描述猪口蹄疫病毒（FMDV）传播的文献，并利用这些数据来估计传播参数。分析表明，猪直接接触时FMDV传播得非常快。然而，当有物理屏障分隔感染猪和易感未接种疫苗猪时，传播会减少。在猪的脚跟球部进行单次皮内病毒注射接种疫苗时，可预防病毒感染，但当猪直接接触未接种疫苗或已接种疫苗的FMDV感染猪时，则无法预防感染。观察发现，物理隔离与疫苗接种相结合可阻断传播。疫苗接种和隔离在估计每日新感染数量方面会产生显著差异。实验性传播研究表明，疫苗接种和物理隔离的联合作用可显著减少传播（R<1），这对于控制农场间传播是一个非常重要的结果。
