SARS outbreaks in Ontario, Hong Kong and Singapore: The role of diagnosis and isolation as a control mechanism

G. Chowell, P. W. Fenimore, M. A. Castillo-Garsow, Carlos Castillo-Chavez

Research output: Contribution to journalArticle

135 Citations (Scopus)

Abstract

In this article we use global and regional data from the SARS epidemic in conjunction with a model of susceptible, exposed, infective, diagnosed, and recovered classes of people ("SEIJR") to extract average properties and rate constants for those populations. The model is fitted to data from the Ontario (Toronto) in Canada, Hong Kong in China and Singapore outbreaks and predictions are made based on various assumptions and observations, including the current effect of isolating individuals diagnosed with SARS. The epidemic dynamics for Hong Kong and Singapore appear to be different from the dynamics in Toronto, Ontario. Toronto shows a very rapid increase in the number of cases between March 31st and April 6th, followed by a significant slowing in the number of new cases. We explain this as the result of an increase in the diagnostic rate and in the effectiveness of patient isolation after March 26th. Our best estimates are consistent with SARS eventually being contained in Toronto, although the time of containment is sensitive to the parameters in our model. It is shown that despite the empirically modeled heterogeneity in transmission, SARS' average reproductive number is 1.2, a value quite similar to that computed for some strains of influenza (J. Math. Biol. 27 (1989) 233). Although it would not be surprising to see levels of SARS infection higher than 10% in some regions of the world (if unchecked), lack of data and the observed heterogeneity and sensitivity of parameters prevent us from predicting the long-term impact of SARS. The possibility that 10 or more percent of the world population at risk could eventually be infected with the virus in conjunction with a mortality rate of 3-7% or more, and indications of significant improvement in Toronto support the stringent measures that have been taken to isolate diagnosed cases.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalJournal of Theoretical Biology
Volume224
Issue number1
DOIs
StatePublished - Sep 7 2003
Externally publishedYes

Fingerprint

Severe Acute Respiratory Syndrome
Singapore
Hong Kong
Ontario
Isolation
Disease Outbreaks
Patient Isolation
China
Human Influenza
Canada
at-risk population
Viruses
funding
influenza
Mortality
Rate constants
Infection
Reproductive number
Population
viruses

Keywords

  • Outbreak
  • SARS
  • SEIJR

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)

Cite this

SARS outbreaks in Ontario, Hong Kong and Singapore : The role of diagnosis and isolation as a control mechanism. / Chowell, G.; Fenimore, P. W.; Castillo-Garsow, M. A.; Castillo-Chavez, Carlos.

In: Journal of Theoretical Biology, Vol. 224, No. 1, 07.09.2003, p. 1-8.

Research output: Contribution to journalArticle

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