Variables | Description |

X | Susceptible class |

Y | Latently infected (exposed) class |

Z | Infected class |

$\Lambda $ | Recruitment rate into the population |

$\mu $ | Natural death rate |

d | Death rate due to infection |

$\beta $ | Probability rate of transmission |

${r}_{1}$ | Treatment rate for exposed class |

${r}_{2}$ | Treatment rate for infected class |

k | Infection rate for exposed individuals |

${k}_{1}$ | Progression rate of exposed class |

${k}_{2}$ | Progression rate of infected class |

$\eta $ | Rate of infectiousness of infected class, where $\eta >1$ |