Dengue and the risk of urban yellow fever reintroduction in São Paulo State, Brazil.
OBJECTIVE
To propose a mathematical method for the estimation of the Basic Reproduction Number, R0, of urban yellow fever in a dengue-infested area.


METHODS
The method is based on the assumption that, as the same vector (Aedes aegypti) causes both infections, all the quantities related to the mosquito, estimated from the initial phase of dengue epidemic, could be applied to yellow fever dynamics. It is demonstrated that R0 for yellow fever is, on average, 43% lower than that for dengue. This difference is due to the longer dengue viremia and its shorter extrinsic incubation period.


RESULTS
In this study the analysis was expanded to the epidemiological situation of dengue in S o Paulo in the year 2001. The total number of dengue cases increased from 3,582 in 2000 to 51,348 in 2001. It was then calculated R0 for yellow fever for every city which have shown R0 of dengue greater than 1. It was also estimated the total number of unprotected people living in highly risky areas for urban yellow fever.


CONCLUSIONS
Currently there is a great number of non-vaccinated people living in Aedes aegypti infested area in the state of São Paulo.
Massad
Eduardo
E
Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil. edmassad@usp.br
Burattini
Marcelo Nascimento
MN
Coutinho
Francisco Antonio Bezerra
FA
Lopez
Luiz Fernandes
LF
D000330:Aedes / Q000821:virology; D000818:Animals; D001938:Brazil / Q000453:epidemiology; D021821:Communicable Diseases, Emerging / Q000453:epidemiology* / Q000517:prevention & control; D003715:Dengue / Q000453:epidemiology*; D004196:Disease Outbreaks; D006801:Humans; D007303:Insect Vectors / Q000821:virology; D008962:Models, Theoretical; D012307:Risk Factors; D014504:Urban Health; D015004:Yellow Fever / Q000453:epidemiology* / Q000517:prevention & control; D022341:Yellow Fever Vaccine
D022341:Yellow Fever Vaccine