The Impact of Host-Based Early Warning on Disease Outbreaks

Mark Hernandez; Lauren E Milechin; Shakti K Davis; Rich DeLaura; Kajal T Claypool; Albert Swiston

In the previous section, we considered the standard SEIR model, which describes disease spread without any public health interventions. To quantitatively evaluate an outbreak scenario with additional measures, the parameters and compartments of the SEIR model can be modified to reflect policy choices or new early warning technologies. Two policies currently considered as standards in handling possible outbreaks rely on self-monitoring to implement voluntary isolation or quarantining all individuals that may have been exposed to a pathogen. Isolation applies to individuals who are already ill, whereas quarantine applies to individuals who may have been exposed but have not yet shown symptoms. The first policy, self-monitoring and reporting, which assumes individuals self-report when they develop symptoms, allows for additional infections during the time delay between the onset of symptoms and isolation; however, it does not account for the logistical and financial cost of quarantine. The second policy, quarantining the entire population, is effective in reducing additional transmissions but has a prohibitively onerous costs for large populations. In an effort to explore the impact of a host-based early warning system, we modified the SEIR model to simulate a third policy, quarantine-on-alert, in which individuals are only quarantined when prompted by a host-based early warning system. We hypothesized that the early notification of incipient illness will allow for reductions in pathogen transmission while minimizing the number of quarantined individuals. We then assessed each of these three new policy-dependent SEIR models.