Decoding of Infection and Transmission Dynamics
This section contains: Model architecture, Differential equations, and Equation parameterization.
Model Architecture
Differential Equations
Fruit Bats (SIR)
$$
\begin{aligned}
\frac{dS_B}{dt} &= \psi_B - \mu_B S_B
- \left(\beta_B \frac{F I_B + I_B}{N_B}\right) S_B \, f_t f_h, \\
\frac{dI_B}{dt} &= \left(\beta_B \frac{F I_B + I_B}{N_B}\right) S_B \, f_t f_h
- \mu_B I_B - \gamma_B I_B, \\
\frac{dR_B}{dt} &= \gamma_B I_B - \mu_B R_B.
\end{aligned}
$$
Intermediate Hosts (Pigs/Cattle/Cats/Dogs/Rodents/Horses) (SEIR)
$$
\begin{aligned}
\frac{dS_I}{dt} &= \psi_I - \mu_I S_I
- \Bigg[\beta_{BI}\left(\frac{F I_B + I_B}{N_B}\right) f_t f_h + \beta_I \left(\frac{I_I}{N_I}\right)\Bigg] S_I, \\
\frac{dE_I}{dt} &= \Bigg[\beta_{BI}\left(\frac{F I_B + I_B}{N_B}\right) f_t f_h + \beta_I \left(\frac{I_I}{N_I}\right)\Bigg] S_I
- \mu_I E_I - \rho_I E_I - \sigma_I E_I, \\
\frac{dI_I}{dt} &= \rho_I E_I
- (\gamma_I + \omega) I_I - (\delta_I + \mu_I) I_I, \\
\frac{dR_I}{dt} &= (\gamma_I + \omega) I_I + \sigma_I E_I - \mu_I R_I.
\end{aligned}
$$
Humans (SEIR)
$$
\begin{aligned}
\frac{dS_H}{dt} &= \psi_H - \mu_H S_H
- \Bigg[\beta_{BH}\left(\frac{F I_B + I_B}{N_B}\right) f_t f_h
+ \beta_I \left(\frac{I_I}{N_I}\right)
+ \beta_H \left(\frac{k I_H + (1-k) I_H}{N_H}\right)\Bigg](1-\theta \pi \varepsilon)\, S_H, \\
\frac{dE_H}{dt} &= \Bigg[\beta_{BH}\left(\frac{F I_B + I_B}{N_B}\right) f_t f_h
+ \beta_I \left(\frac{I_I}{N_I}\right)
+ \beta_H \left(\frac{k I_H + (1-k) I_H}{N_H}\right)\Bigg](1-\theta \pi \varepsilon)\, S_H
- \rho_H E_H - \mu_H E_H - \sigma_H E_H, \\
\frac{dI_H}{dt} &= \rho_H E_H
- (\gamma_H + \alpha) I_H - (\delta_H + \mu_H) I_H, \\
\frac{dR_H}{dt} &= (\gamma_H + \alpha) I_H + \sigma_H E_H - \mu_H R_H.
\end{aligned}
$$
Equation Parameterization
| Sl. No | Parameter | Description |
|---|---|---|
| 1 | S_B | Susceptible population of bats |
| 2 | I_B | Infected population of bats |
| 3 | R_B | Recovered population of bats |
| 4 | S_I | Susceptible population of intermediate hosts |
| 5 | E_I | Exposed population of intermediate hosts |
| 6 | I_I | Infected population of intermediate hosts |
| 7 | R_I | Recovered population of intermediate hosts |
| 8 | S_H | Susceptible population of humans |
| 9 | E_H | Exposed population of humans |
| 10 | I_H | Infected population of humans |
| 11 | R_H | Recovered population of humans |
| 12 | N_B | Total bat population |
| 13 | N_I | Total intermediate-host population |
| 14 | N_H | Total human population |
| 15 | k | Proportion of superspreaders among infected humans |
| 16 | F | Food contaminated by bat saliva/blood/urine (contamination factor/index) |
| 17 | β_B | Transmission rate in bats |
| 18 | β_I | Transmission rate in intermediate hosts (within-host group) |
| 19 | β_H | Transmission rate in humans (within-human group) |
| 20 | β_BI | Transmission from bats to intermediate hosts |
| 21 | β_BH | Transmission from bats to humans |
| 22 | γ_B | Recovery rate of bats |
| 23 | γ_I | Recovery rate of intermediate hosts |
| 24 | γ_H | Recovery rate of humans |
| 25 | σ_I | Additional exposure progression rate (intermediate hosts) |
| 26 | σ_H | Additional exposure progression rate (humans) |
| 27 | ρ_I | Progression rate from exposed to infected (intermediate hosts) |
| 28 | ρ_H | Progression rate from exposed to infected (humans) |
| 29 | ψ_B | Inclusion/recruitment rate of bats |
| 30 | ψ_I | Inclusion/recruitment rate of intermediate hosts |
| 31 | ψ_H | Inclusion/recruitment rate of humans |
| 32 | μ_B | Natural death rate of bats |
| 33 | μ_I | Natural death rate of intermediate hosts |
| 34 | μ_H | Natural death rate of humans |
| 35 | δ_I | Disease-induced death rate of intermediate hosts |
| 36 | δ_H | Disease-induced death rate of humans |
| 37 | f_t | Environmental modifier: temperature factor |
| 38 | f_h | Environmental modifier: relative humidity factor |
| 39 | ω | Treatment effect on infected pigs (intermediate hosts) |
| 40 | θ | Enhanced personal hygiene due to public enlightenment |
| 41 | ε | Rate of public enlightenment |
| 42 | π | Surveillance coverage |
| 43 | α | Treatment effect on infected humans |