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Compartmental models simplify the mathematical modelling of infectious diseases. The population is assigned to compartments with labels - for example, S, I,  or R, (Susceptible, Infectious, or Recovered). People may progress between compartments. The order of the labels usually shows the flow patterns between the compartments; for example SEIS means susceptible, exposed, infectious, then susceptible again.

Compartmental models simplify the mathematical modelling of infectious diseases. The population is assigned to compartments with labels - for example, S, I,  or R, (Susceptible, Infectious, or Recovered). People may progress between compartments. The order of the labels usually shows the flow patterns between the compartments; for example SEIS means susceptible, exposed, infectious, then susceptible again.

'''<font color="#ff8000">房室模型Compartmental models</font>'''简化了传染病传播的数学模型。人群被划分为带有标签的类别，例如，S，I，和 R，(易感者，染病者和康复者)。不同类别人群的标签会发生变化。标签的变化反映了不同类别人群之间的转化模式，例如SEIS模型代表易感者类型可以转变为暴露者类型、暴露者类型可以转变为染病者类型，染病者类型可以再次转变回易感者类型。

'''<font color="#ff8000">仓室模型Compartmental models</font>'''简化了传染病传播的数学模型。人群被划分为带有标签的类别，例如，S，I，和 R，(易感者，染病者和康复者)。不同类别人群的标签会发生变化。标签的变化反映了不同类别人群之间的转化模式，例如SEIS模型代表易感者类型可以转变为暴露者类型、暴露者类型可以转变为染病者类型，染病者类型可以再次转变回易感者类型。

==[[用户:Agnes|Agnes]]（[[用户讨论:Agnes|讨论]]）[翻译]译者知识水平限制，通过多方查询资料对传染病模型有了基本了解之后，在“SEIS means susceptible, exposed, infectious, then susceptible again”的翻译中，选择增添了一些成分，但此部分的翻译仍然存疑

==[[用户:Agnes|Agnes]]（[[用户讨论:Agnes|讨论]]）[翻译]译者知识水平限制，通过多方查询资料对传染病模型有了基本了解之后，在“SEIS means susceptible, exposed, infectious, then susceptible again”的翻译中，选择增添了一些成分，但此部分的翻译仍然存疑

The SIR model is one of the simplest compartmental models, and many models are derivatives of this basic form. The model consists of three compartments:  

The SIR model is one of the simplest compartmental models, and many models are derivatives of this basic form. The model consists of three compartments:  

'''<font color="#ff8000">SIR 模型</font>'''是最简单的房室模型之一，许多模型都是这种基本模型的衍生物。该模型由三种类型的人群组成:

'''<font color="#ff8000">SIR 模型</font>'''是最简单的仓室模型之一，许多模型都是这种基本模型的衍生物。该模型由三种类型的人群组成:

:'''S''': The number of '''s'''usceptible individuals. When a susceptible and an infectious individual come into "infectious contact", the susceptible individual contracts the disease and transitions to the infectious compartment.

:'''S''': The number of '''s'''usceptible individuals. When a susceptible and an infectious individual come into "infectious contact", the susceptible individual contracts the disease and transitions to the infectious compartment.

The dynamics of an epidemic, for example, the flu, are often much faster than the dynamics of birth and death, therefore, birth and death are often omitted in simple compartmental models.  The SIR system without so-called vital dynamics (birth and death, sometimes called demography) described above can be expressed by the following set of ordinary differential equations:

The dynamics of an epidemic, for example, the flu, are often much faster than the dynamics of birth and death, therefore, birth and death are often omitted in simple compartmental models.  The SIR system without so-called vital dynamics (birth and death, sometimes called demography) described above can be expressed by the following set of ordinary differential equations:

流行病导致的动态变化，例如流感，往往比出生和死亡的导致的动态变化更快，因此，出生和死亡往往被简单的'''<font color="#ff8000">房室模型comparenmental models</font>'''所忽略。没有上述所谓的生命动力学(出生和死亡，有时称为人口统计学)的 SIR 系统可以用下列一组常微分方程表示:

流行病导致的动态变化，例如流感，往往比出生和死亡的导致的动态变化更快，因此，出生和死亡往往被简单的'''<font color="#ff8000">仓室模型comparenmental models</font>'''所忽略。没有上述所谓的生命动力学(出生和死亡，有时称为人口统计学)的 SIR 系统可以用下列一组常微分方程表示:

MSIR compartmental modelTo indicate this mathematically, an additional compartment is added, M(t). This results in the following differential equations:

MSIR compartmental modelTo indicate this mathematically, an additional compartment is added, M(t). This results in the following differential equations:

【图8：MSIR compartmental model. To indicate this mathematically, an additional compartment is added, M(t). This results in the following differential equations:MSIR 房室模型为了从数学上表示这一点，增加了一个额外的分类，M(t)。这导致了下列微分方程:】

【图8：MSIR compartmental model. To indicate this mathematically, an additional compartment is added, M(t). This results in the following differential equations:MSIR 仓室模型为了从数学上表示这一点，增加了一个额外的分类，M(t)。这导致了下列微分方程:】

To be more precise, these models are only valid in the thermodynamic limit, where the population is effectively infinite. In stochastic models, the long-time endemic equilibrium derived above, does not hold, as there is a finite probability that the number of infected individuals drops below one in a system. In a true system then, the pathogen may not propagate, as no host will be infected. But, in deterministic mean-field models, the number of infected can take on real, namely, non-integer values of infected hosts, and the number of hosts in the model can be less than one, but more than zero, thereby allowing the pathogen in the model to propagate. The reliability of compartmental models is limited to compartmental applications.

To be more precise, these models are only valid in the thermodynamic limit, where the population is effectively infinite. In stochastic models, the long-time endemic equilibrium derived above, does not hold, as there is a finite probability that the number of infected individuals drops below one in a system. In a true system then, the pathogen may not propagate, as no host will be infected. But, in deterministic mean-field models, the number of infected can take on real, namely, non-integer values of infected hosts, and the number of hosts in the model can be less than one, but more than zero, thereby allowing the pathogen in the model to propagate. The reliability of compartmental models is limited to compartmental applications.