Infectious disease surveillance

Overview

This app teaches the topic of Infectious disease surveillance and demonstrates the effect of the type and extent of surveillance on the dynamics of an infectious disease in a population, including the course and outcome of an epidemic. Read about the model in the “Model” tab. Then do the tasks described in the “What to do” tab.

Learning Objectives

The Model

Model Overview

For this compartmental model, we track the following compartments/stages:

The model can be extended to include a reported compartment. This compartment would represent for example the US Centers for Disease Control and Prevention (CDC) to which health systems report the observed cases of disease at some rate(s).

In addition to specifying the compartments of a model, we need to specify the dynamics determining the changes for each compartment. In general, more compartments leads to more processes and more parameters governing these processes.

For this model, we include the following processes:

Model Implementation

The flow diagram and the set of ordinary differential equations (ODE) which are used to implement this model are as follows:

Flow diagram for this model.

Flow diagram for this model.

\[\dot S = m - S(b_P P + b_A A + b_I I) + wR - nS\] \[\dot P = S (b_P P + b_A A + b_I I) - P(g_P + r_P + n) \] \[\dot A = f g_P P - A(r_A + n) \] \[\dot I = (1-f) g_P P - I (r_I + n + d) \] \[\dot R = r_PP + r_A A + r_I I - wR \] \[\dot D = dD\]

What to do

The tasks below are described in a way that assumes everything is in units of months (rate parameters, therefore, have units of inverse months). If any quantity is not given in those units, you need to convert it first (e.g. if it says a year, you need to convert it to 12 months).

Task 1:

Task 2:

Task 3:

Task 4:

Task 5:

Further Information

References

Brabazon, E. D., A. Sheridan, P. Finnegan, M. W. Carton, and D. Bedford. 2015. “Under-reporting of notifiable infectious disease hospitalizations: Significant improvements in the Irish context.” Epidemiology and Infection 143 (6): 1166–74. https://doi.org/10.1017/S0950268814001733.

Jelastopulu, E., G. Merekoulias, and E. C. Alexopoulos. 2010. “Underreporting of communicable diseases in the prefecture of Achaia, Western Greece, 1999-2004 - Missed opportunities for early intervention.” Eurosurveillance 15 (21): 1999–2004. https://doi.org/10.2807/ese.15.21.19579-en.

Kazerooni, P. A., M. Fararouei, M. Nejat, M. Akbarpoor, and Z. Sedaghat. 2018. “Under-ascertainment, under-reporting and timeliness of Iranian communicable disease surveillance system for zoonotic diseases.” Public Health 154: 130–35. https://doi.org/10.1016/j.puhe.2017.10.029.