title: The 1918 influenza A epidemic in the city of São Paulo, Brazil.
abstract: The 1918 pandemic H1N1 outbreak in the city of São Paulo is revisited. The outbreak lasted for 10 weeks and reached 116,771 officially recorded cases amongst 523,194 inhabitants. The total number of deaths summed up to 5331, with a lethality rate of 4.5% and an overall mortality rate of around 1%. We propose a mathematical model that tallies available data with good accuracy and allows the estimation of the basic reproductive number, R(0). The model showed a remarkably good accuracy in retrieving the real data from São Paulo city outbreak considering the total number of recorded cases and deaths and the timing of the outbreak. The basic reproduction number calculated of 2.68 can be compared to estimates carried out for other flu strains, like the estimates for H3N2, whose values ranged from 1.5 to 2.5. We hypothesize that the Southern parts of the world in which there was relatively little impact of the Great War, like South America, suffered a much lower H1N1 influenza mortality as compared with that reported for the Northern hemisphere heavily affected by the I World War.
authors.affiliation: School of Medicine, University of São Paulo, Rua Teodoro Sampaio 115, CEP 05405-000, SP, Brazil. edmassad@usp.brb
authors.forename: Eduardo
authors.initials: E
authors.lastname: Massad
authors.forename: Marcelo Nascimento
authors.initials: MN
authors.lastname: Burattini
authors.forename: Francisco Antonio Bezerra
authors.initials: FA
authors.lastname: Coutinho
authors.forename: Luiz Fernandes
authors.initials: LF
authors.lastname: Lopez
mesh_terms: D001938:Brazil / Q000453:epidemiology; D004196:Disease Outbreaks; D049673:History, 20th Century; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000266:history; D015233:Models, Statistical