title: Estimate of Novel Influenza A/H1N1 cases in Mexico at the early stage of the pandemic with a spatially structured epidemic model.
abstract: Determining the number of cases in an epidemic is fundamental to properly evaluate several disease features of high relevance for public health policies such as mortality, morbidity or hospitalization rates. Surveillance efforts are however incomplete especially at the early stage of an outbreak due to the ongoing learning process about the disease characteristics. An example of this is represented by the number of H1N1 influenza cases in Mexico during the first months of the current pandemic. Several estimates using backtrack calculation based on imported cases from Mexico in other countries point out that the actual number of cases was likely orders of magnitude larger than the number of confirmed cases. Realistic computational models fed with the best available estimates of the basic disease parameters can provide an ab-initio calculation of the number of cases in Mexico as other countries. Here we use the Global Epidemic and Mobility (GLEaM) model to obtain estimates of the size of the epidemic in Mexico as well as of imported cases at the end of April and beginning of May. We find that the reference range for the number of cases in Mexico on April 30th is 121,000 to 1,394,000 in good agreement with the recent estimates by Lipsitch et al. [M. Lipsitch, PloS One 4:e6895 (2009)]. The number of imported cases from Mexico in several countries is found to be in good agreement with the surveillance data.
authors.affiliation: Computational Epidemiology Lab, ISI Foundation, Turin, Italy.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Colizza
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vespignani
authors.forename: Nicola
authors.initials: N
authors.lastname: Perra
authors.forename: Chiara
authors.initials: C
authors.lastname: Poletto
authors.forename: Bruno
authors.initials: B
authors.lastname: Gonçalves
authors.forename: Hao
authors.initials: H
authors.lastname: Hu
authors.forename: Duygu
authors.initials: D
authors.lastname: Balcan
authors.forename: Daniela
authors.initials: D
authors.lastname: Paolotti
authors.forename: Wouter
authors.initials: W
authors.lastname: Van den Broeck
authors.forename: Michele
authors.initials: M
authors.lastname: Tizzoni
authors.forename: Paolo
authors.initials: P
authors.lastname: Bajardi
authors.forename: Jose J
authors.initials: JJ
authors.lastname: Ramasco