A SIMULATION-MODEL OF THE EPIDEMIOLOGY OF URBAN DENGUE FEVER - LITERATURE ANALYSIS, MODEL DEVELOPMENT, PRELIMINARY VALIDATION, AND SAMPLES OF SIMULATION RESULTS

We have developed a pair of stochastic simulation models that describe the daily dynamics of dengue virus transmission in the urban environm ent. Our goal has been to construct comprehensive models that take int o account the majority of factors known to influence dengue epidemiolo gy. The models have an orientation toward site-specific data and are d esigned to be used by operational programs as well as researchers. The first model, the container-inhabiting mosquito simulation model (CIMS iM), a weather-driven dynamic Life-table model of container-inhabiting mosquitoes such as Aedes aegypti, provides inputs to the transmission model, the dengue simulation model (DENSiM); a description and valida tion of the entomology model was published previously. The basis of th e transmission model is the simulation of a human population growing i n response to country- and age-specific birth and death rates. An acco unting of individual serologies is maintained by type of dengue virus, reflecting infection and birth to seropositive mothers. Daily estimat es of adult mosquito survival, gonotrophic development, and the weight and number of emerging females from the CIMSiM are used to create the biting mosquito population in the DENSiM. The survival and emergence values determine the size of the population while the rate of gonotrop hic development and female weight estimates influence biting frequency . Temperature and titer of virus in the human influences the extrinsic incubation period; titer may also influence the probability of transf er of virus from human to mosquito. The infection model within the DEN SiM accounts for the development of virus within individuals and its p assage between both populations. As in the case of the CIMSiM, the spe cific values used for any particular phenomenon are on menus where the y can be readily changed. It is possible to simulate concurrent epidem ics involving different serotypes. To provide a modicum of validation and to demonstrate the parameterization process for a specific locatio n, we compare simulation results with reports on the nature of epidemi cs and seroprevalence of antibody in Honduras in low-lying coastal urb anizations and Tegucigalpa following the initial introduction of dengu e-1 in 1978 into Central America. We conclude with some additional exa mples of simulation results to give an indication of the types of ques tions that can be investigated with the models.