Wednesday, 17 November 2004
D0567

Hidden dynamics of Dengue epidemics in Brazil

Nicolas Degallier, nicolas.degallier@ird.fr1, Charly Favier, charly.favier@lodyc.jussieu.fr1, Jean-Philippe Boulanger, Jean-Philippe.Boulanger@lodyc.jussieu.fr1, Christophe E. Menkes, menkes@lodyc.jussieu.fr1, Cristiane Oliveira, Cristianecrs@aol.com2, José R.C. Lima3, and Bernard Mondet, mondet@dakar.ird.sn4. (1) Institut de Recherche pour le Développement (IRD), UR034, LODYC tour 45-55, 4e étage 4 place Jussieu, Case 100, Paris, Seine, France, (2) DIVAL, SES, SAIN Estrada do Contorno do Bosque, lote 04, Brasilia, DF, Brazil, (3) CEVEPI - SES, Av. Almirante Barroso, 600, Praia de Iracema, Fortaleza, Ceara, Brazil, (4) IRD - UR034, Centre de Hann, BP 1386, route des Père Maristes, Dakar, Senegal

During epidemics of Dengue fever, Ro, the basic reproduction number of the disease, depends mainly on the contact rate between the vectors and susceptible people, and on the duration of the viremic phase of the illness. We will show that during real epidemics, the Ro may be misleading about the outcomes of a transmission model, especially when the proportion of « imported » vs. « autochthonous » cases is high, and mosquito control activities are efficient. A new method is presented to estimate the Ro from the initial phase of Dengue outbreaks and a model is proposed to take into account exogenous cases during epidemics. It is thus shown that epidemics may occur even if the Ro value is below one.


Species 1: Diptera Culicidae Aedes aegypti (yellow fever mosquito)
Species 2: Flaviviridae Flavivirus Dengue (Dengue fever)
Keywords: epidemics, modeling

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