Mimmo Iannelli

Mitigation Measures for Pandemic Influenza in Italy: An Individual Based Model Considering Different Scenarios

Background Individual-based models can provide the most reliable estimates of the spread of infectious diseases. In the present study, we evaluated the diffusion of pandemic influenza in Italy and the impact of various control measures, coupling a global SEIR model for importation of cases with an individual based model (IBM) describing the Italian epidemic. Methodology/Principal Findings We co-located the Italian population (57 million inhabitants) to households, schools and workplaces and we assigned travel destinations to match the 2001 census data. We considered different R0 values (1.4; 1.7; 2), evaluating the impact of control measures (vaccination, antiviral prophylaxis -AVP-, international air travel restrictions and increased social distancing). The administration of two vaccine doses was considered, assuming that first dose would be administered 1-6 months after the first world case, and different values for vaccine effectiveness (VE). With no interventions, importation would occur 37–77 days after the first world case. Air travel restrictions would delay the importation of the pandemic by 7–37 days. With an R0 of 1.4 or 1.7, the use of combined measures would reduce clinical attack rates (AR) from 21–31% to 0.3–4%. Assuming an R0 of 2, the AR would decrease from 38% to 8%, yet only if vaccination were started within 2 months of the first world case, in combination with a 90% reduction in international air traffic, closure of schools/workplaces for 4 weeks and AVP of household and school/work close contacts of clinical cases. Varying VE would not substantially affect the results. Conclusions This IBM, which is based on country-specific demographic data, could be suitable for the real-time evaluation of measures to be undertaken in the event of the emergence of a new pandemic influenza virus. All preventive measures considered should be implemented to mitigate the pandemic.

Optimal harvesting for periodic age-dependent population dynamics

Here we investigate the optimal harvesting problem for some periodic age-dependent population dynamics; namely, we consider the linear Lotka--McKendrick model with periodic vital rates and a periodic forcing term that sustains oscillations. Existence and uniqueness of a positive periodic solution are demonstrated and the existence and uniqueness of the optimal control are established. We also state necessary optimality conditions. A numerical algorithm is developed to approximate the optimal control and the optimal harvest. Some numerical results are presented.

Global behavior of an age-structured epidemic model

The global behavior of the general

Separable models in age-dependent population dynamics

s \to i \to s

Gender-structured population modeling : mathematical methods, numerics, and simulations

age-structured epidemic model in a population of constant size is obtained. It is shown that there is a sharp threshold which determines the existence and global stability of an endemic state; hence, periodic solutions are ruled out. The threshold is identified as the spectral radius of a positive linear operator. The analysis employs the theory of semigroups and positive operator methods, and is based on the formulation of the problem as an abstract differential equation in a Banach space.

Endemic thresholds and stability in a class of age-structured epidemics

A class of population models is considered in which the parameters such as fecundity, mortality and interaction coefficients are assumed to be age-dependent. Conditions for the existence, stability and global attractivity of steady-state and periodic solutions are derived. The dependence of these solutions on the maturation periods is analyzed. These results are applied to specific single and multiple population models. It is shown that periodic solutions cannot occur in a general class of single population age-dependent models. Conditions are derived that determine whether increasing the maturation period has a stabilizing effect. In specific cases, it is shown that any number of switches in stability can occur as the maturation period is increased. An example is given of predator-prey model where each one of these stability switches corresponds to a stable steady state losing its stability via a Hopf bifurcation to a periodic solution and regaining its stability upon further increase of the maturation period.

Analytical and numerical results for the age-structured S-I-S epidemic model with mixed inter-intracohort transmission

Preface 1. Historical perspective of mathematical demography 2. Gender structure and the problem of modeling marriages 3. Well-posedness of the Fredrickson-Hoppensteadt two-sex model 4. Numerical methods 5. Age profiles and exponential growth Appendix Bibliography Index.

A class of nonlinear diffusion problems in age-dependent population dynamics☆

An age-structured epidemic model is analyzed when the fertility, mortality and removal rates depend on age. For certain general forms of the force of infection terms, endemic threshold criteria are derived and the stability of steady state solutions is determined. The relation between age-structured models of this type and catalytic curve models of epidemics is derived. The possibility of identifying vertically transmitted diseases from the catalytic curve is demonstrated.

Existence and Regularity for a Class of Integrodifferential Equations of Parabolic Type

A model which describes the dynamics of an

Existence and uniqueness of endemic states for the age-structured S–I–R epidemic model

S \to I \to S