DENGUE EPIDEMICS IN MIDDLE-SOUTH OF BRAZIL: CLIMATE CONSTRAINTS AND SOME SOCIAL ASPECTS

Dengue is currently one of the most serious worldwide public health problems. It is a disease of the tropical world, in which most of Latin America is located and where the environment and climate provide ideal conditions for the Aedes mosquito (aegypti and albopictus) to thrive. In addition the socio-cultural environment (urbanization and lifestyle) and an ineffectiveness of public health policies, result in severe epidemics of the disease. This research aims to analyze incidences of dengue fever in three different cities in Brazil: Campo Grande/Mato Grosso do Sul, Maringa/Parana and Ribeirao Preto/São Paulo and its statistical relationship to climate by correlating different climate variables to dengue incidence. Daily temperature analysis also shows significant correlation (R=0.70 and P>0.99) with disease incidence subject to a 7 days lag. In addition to climate and environmental factors, the mobility of population through by imported cases, has also been investigated. The results show the complexity of disease, in a strict relation between the environment (weather) and the mobility of the population, the circulation of different serotypes, the disposal of solid waste, debris and abandoned swimming pools, consequence ofthe indifference of the population to situations of risk and vulnerability to the disease. An important point to highlight is that, even in different cities, the epidemics followed a similar pattern, emphasizing the importance of climate variables (should also add the hypothesis of travel, serotype). Our study uncovered important relationships between dengue epidemics and climate, although more detailed studies on both serotype and transmission in cities are necessary to further understand the factors behind disease transmission. Our results could assist local health agencies on implementing appropriate early warning systems monitoring and preventive control actions by monitoring temperature conditions prior to the epidemics.Key words: Dengue, climate, society, Centro-south, Brazi

The Effect of Temperature on West Nile Virus Transmission Dynamics

West Nile virus (WNV) is a vector-borne disease that first appeared in New York in 1999, then in Southern Ontario, Canada in 2002. Since its arrival, WNV has rapidly spread across the North American continent to establish itself as a seasonal endemic infection. Among other environmental variables, temperature is the primary determinant of WNV transmission dynamics. In this dissertation, the relationship between temperature and WNV transmission dynamics is investigated and a single-season predictive model that explicitly accounts for temperature in various biological and epidemiological processes is proposed. First, we develop a mosquito abundance model where temperature is the driving force behind mosquito development, survival, and diapause. Then, the model is extended to include the WNV transmission cycle between mosquitoes and birds. Under simplifying assumptions, we derive an expression for the basic reproduction number and analyze its dependence on temperature. The transmission model was applied to the Peel Region in Southern Ontario for validation. Numerical results demonstrate the capacity of the model to capture the within-season trends of mosquito- and WNV- surveillance data. The proposed model can potentially be used as a real-time predictive tool to inform public health policy