The effect of governance structures on optimal control of two-patch epidemic models.

Infectious diseases continue to pose a significant threat to the health of humans globally. While the spread of pathogens transcends geographical boundaries, the management of infectious diseases typically occurs within distinct spatial units, determined by geopolitical boundaries. The allocation of management resources within and across regions (the "governance structure") can affect epidemiological outcomes considerably, and policy-makers are often confronted with a choice between applying control measures uniformly or differentially across regions. Here, we investigate the extent to which uniform and non-uniform governance structures affect the costs of an infectious disease outbreak in two-patch systems using an optimal control framework. A uniform policy implements control measures with the same time varying rate functions across both patches, while these measures are allowed to differ between the patches in a non-uniform policy. We compare results from two systems of differential equations representing transmission of cholera and Ebola, respectively, to understand the interplay between transmission mode, governance structure and the optimal control of outbreaks. In our case studies, the governance structure has a meaningful impact on the allocation of resources and burden of cases, although the difference in total costs is minimal. Understanding how governance structure affects both the optimal control functions and epidemiological outcomes is crucial for the effective management of infectious diseases going forward.

Five approaches to the suppression of SARS-CoV-2 without intensive social distancing.

Initial efforts to mitigate transmission of SARS-CoV-2 relied on intensive social distancing measures such as school and workplace closures, shelter-in-place orders and prohibitions on the gathering of people. Other non-pharmaceutical interventions for suppressing transmission include active case finding, contact tracing, quarantine, immunity or health certification, and a wide range of personal protective measures. Here we investigate the potential effectiveness of these alternative approaches to suppression. We introduce a conceptual framework represented by two mathematical models that differ in strategy. We find both strategies may be effective, although both require extensive testing and work within a relatively narrow range of conditions. Generalized protective measures such as wearing face masks, improved hygiene and local reductions in density are found to significantly increase the effectiveness of targeted interventions.

Five approaches to the suppression of SARS-CoV-2 without intensive social distancing.

Initial efforts to mitigate transmission of SARS-CoV-2 relied on intensive social distancing measures such as school and workplace closures, shelter-in-place orders, and prohibitions on the gathering of people. Other non-pharmaceutical interventions for suppressing transmission include active case finding, contact tracing, quarantine, immunity or health certification, and a wide range of personal protective measures. Here we investigate the potential effectiveness of these alternative approaches to suppression. We introduce a conceptual framework represented by two mathematical models that differ in strategy. We find both strategies may be effective, although both require extensive testing and work within a relatively narrow range of conditions. Generalized protective measures such as wearing face masks, improved hygiene, and local reductions in density are found to significantly increase the effectiveness of targeted interventions.

Modeling the population impacts of avian malaria on Hawaiian honeycreepers: Bifurcation analysis and implications for conservation.

Avian malaria is a mosquito-borne parasitic disease of birds caused by protists of the genera Plasmodium, most notably Plasmodium relictum. This disease has been identified as a primary cause of the drastic decline and extinctions of birds, in particular Hawaiian honeycreepers (Drepanidinae), where rates of mortality may exceed 90%. We formulate an epizootiological model of the transmission dynamics of avian malaria between populations of bird hosts and mosquito vectors using a system of compartmental ordinary differential equations. We derive the basic reproduction number as well as criteria for the existence and local stability of disease-free and enzootic equilibria. These results provide useful information for evaluating management strategies. A local sensitivity analysis of certain model invariants to uncertain parameter values is performed to ascertain which biological factors have the largest impact on ecological outcomes and, in particular, long-term bird population densities. We discuss and compare the effectiveness of two disease control and conservation strategies: captive propagation of honeycreepers and larval mosquito habitat reduction. We provide examples of combinations of these strategies that either are predicted to eliminate enzootic avian malaria or to increase predicted bird density above a given ecologically meaningful threshold.