ABSTRACT
Dengue, similar to other arboviral diseases, exhibits complex spatiotemporal dynamics. Even at town or village level, individual-based spatially explicit models are required to correctly reproduce epidemic curves. This makes modelling at the regional level (province, country or continent) very difficult and cumbersome. We propose here a first step to build a hierarchized model by constructing a simple analytical expression which reproduces the model output from macroscopic parameters describing each 'village'. It also turns out to be a good approximation of real urban epidermic outbreaks. Subsequently, a regional model could be built by coupling these equations on a lattice.
Subject(s)
Communicable Diseases, Emerging/transmission , Dengue/transmission , Disease Outbreaks , Nonlinear Dynamics , Animals , Communicable Diseases, Emerging/epidemiology , Computer Simulation , Demography , Dengue/epidemiology , Humans , Models, Biological , Models, StatisticalABSTRACT
The risk of dengue virus infection to travelers visiting dengue fever endemic regions was studied through the use of mathematical modeling. A Susceptible-Infected-Recovered (SIR) model is used to describe the transmission of dengue fever (DF) in an endemic region into which tourists enter. The dynamics of a new class of human, the traveler, is incorporated into the systems of first order differential equations in the SIR describing the dynamics of the transmission in the host region. Using standard dynamic analysis methods, the numbers of travelers who become infected with the dengue virus are calculated as a function of the length of time the tourist stays in the region.
Subject(s)
Dengue Virus/isolation & purification , Dengue/epidemiology , Endemic Diseases , Travel , Dengue/transmission , Female , Humans , Incidence , Male , Models, Theoretical , Predictive Value of Tests , Risk Assessment , Survival Rate , Thailand/epidemiologyABSTRACT
The age profiles of the infected populations of two dengue hemorrhagic fever (DHF) epidemics, the 1997 epidemic, in Santiago de Cuba and the 1998 epidemic in Thailand, are compared. Using an age-structured model of disease transmission, the dependence of the forces of infection on age was determined for each epidemic. The difference in the behavior of the two epidemics and the role of primary and secondary infection in the development of DHF are discussed.
Subject(s)
Age Distribution , Disease Outbreaks , Severe Dengue/epidemiology , Adolescent , Adult , Child , Child, Preschool , Cuba/epidemiology , Humans , Infant , Infant, Newborn , Middle Aged , Thailand/epidemiologyABSTRACT
The influence of age structure in the susceptible class of the Susceptible-Infected Recovered (SIR) model used to describe the transmission of dengue hemorrhagic fever (DHF) was studied. This was done by first dividing all of the population classes into cohorts and then writing a set of coupled SIR equations for each cohort. The consequences of assuming different behavior of the transmission rates on the age structure in the DHF incidence rates were determined. In order for the predicted incidence rates to be similar to the DHF incidence patterns observed in several provinces in Thailand during the DHF epidemic in 1998, the transmission rates should be age dependent.
