Epidemiology and Infection

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Epidemiology and Infection (2009), 137:1019-1031 Cambridge University Press
Copyright © 2008 Cambridge University Press

Original Papers

Influenza, Legionnaires' disease and respiratory infections

An approach to estimate the number of SARS cases imported by international air travel

A. GOUBARa1, D. BITARa1 c1, W. C. CAOa2, D. FENGa2, L. Q. FANGa2 and J. C. DESENCLOSa1

a1 Institut de Veille Sanitaire, Infectious Diseases Department, Saint Maurice, France
a2 Beijing Institute of Microbiology and Epidemiology, State Key Laboratory of Pathogen and Biosecurity, Feng Tai District, Beijing, P.R. China
Article author query
goubar a [PubMed]  [Google Scholar]
bitar d [PubMed]  [Google Scholar]
cao wc [PubMed]  [Google Scholar]
feng d [PubMed]  [Google Scholar]
fang lq [PubMed]  [Google Scholar]
desenclos jc [PubMed]  [Google Scholar]


The worldwide spread of severe acute respiratory syndrome (SARS) raised questions about the risk of importation of such infection, in particular by air travel. Entry screening was implemented in some countries although poor evidence on its effectiveness is reported. We developed a model to estimate the number of imported SARS cases between regions, using the 2003 SARS epidemic data to apply this model for two scenarios: from Beijing to Frankfurt and from Hong Kong to London. We back-calculated the data to estimate individuals’ time of infection and built a model where every individual has a probability of being isolated, of traveling, and of being undetected at arrival. The findings, consistent with what was observed in 2003, suggest that entry screening does not affect the predicted number of imported cases. Inversely, importation depends on the transmission dynamic in the country of origin (including control measures in place) and on the intensity of air travel between regions.

(Accepted October 16 2008)

(Online publication December 15 2008)

Key Words:Entry screening; importation; international travel; model


c1 Author for correspondence: Dr D. Bitar, Institut de Veille Sanitaire, Infectious Diseases Department, 12 Rue du Val d'Osne 94415 (F), Saint Maurice Cedex, France. (Email: d.bitar@invs.sante.fr)