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WHO issues guidance on future public health management of SARS

Jonathan Crofts (jonathan.crofts@hpa.org.uk) and Valerie Delpech, Health Protection Agency Communicable Disease Surveillance Centre, London, England.

The World Health Organization (WHO) has published a document describing the SARS alert criteria and a surveillance approach for the post-outbreak period of severe acute respiratory syndrome (SARS) (1). The SARS alert is an operational definition designed to ensure appropriate public health measures are implemented until SARS has been discounted in patients with atypical pneumonia or respiratory distress syndrome. The document sets out new clinical and laboratory case definitions together with recommended public health and infection control measures for managing a SARS 'alert'. It also provides suggestions for an approach to enhanced surveillance, guidance on the clinical presentation, laboratory, and radiological findings to assist clinicians in the diagnosis of SARS.

WHO recommends three different levels of surveillance for member countries based on a risk assessment of the recent outbreak of SARS and the potential for its resurgence:

Potential zone of re-emergence of SARS coronavirus (SARS-CoV)
A country identified as the previous or potential source of a SARS outbreak. Recommended surveillance: special studies for SARS-CoV infections in human and animal populations, SARS alert, and enhanced surveillance for SARS.
Nodal areas
Those countries which experienced sustained local transmission or entry of large numbers of SARS cases in the last outbreak. Recommended surveillance: SARS alert and enhanced surveillance for SARS.
Low risk areas
Those countries who never reported cases or only reported imported cases or had limited local transmission during the last outbreak. Recommended surveillance for clusters of 'alert' cases among healthcare workers, other hospital staff, patients and visitors in the same healthcare unit

The current WHO definition of a SARS alert:

	Two or more healthcare workers in the same healthcare unit fulfilling the clinical case definition of SARS and with illness in the same 10 day period.
	OR Hospital acquired illness in three or more persons (healthcare workers and/or patients and/or visitors) in the same healthcare unit fulfilling the clinical case definition of SARS and with onset of illness in the same 10 day period.

A cumulative total of 8422 SARS cases, with 916 deaths (case fatality rate 11 per cent) attributable to SARS have been reported around the world (3). The news on 5 July that all known chains of person-to-person transmission of the severe acute respiratory syndrome (SARS) virus had been broken highlighted a remarkable public health achievement (2). Following recognition that SARS posed a global threat in mid-March 2003, the disease was successfully contained in less than four months. There is much still to be learnt about the epidemiology and ecology of SARS, however, and resurgence of the disease is a distinct possibility.

For the purpose of international reporting of SARS in the post-outbreak period, WHO requests member states report laboratory confirmed cases only (http://www.who.int/csr/sars/postoutbreak/en/).

In June, the European Commission published a document summarising measures undertaken by EU member states and accession countries to control outbreaks of severe acute respiratory syndrome (4 and references therein).

Eurosurveillance has updated its SARS web page (http://www.eurosurveillance.org/links/sras-01.asp), and will continue to add relevant information and new links in the months ahead.

References:

WHO. Communicable Disease Surveillance and Response. Alert, verification and public health management of SARS in the post-outbreak period. 14 August 2003. (http://www.who.int/csr/sars/postoutbreak/en/)
WHO. Communicable Disease Surveillance and Response. Disease outbreak news: Update 96 - Taiwan, China: SARS transmission interrupted in last outbreak area, 5 July 2003. (http://www.who.int/csr/don/2003_07_05/en/print.html).
WHO. Summary table of SARS cases by country 1 November 2002 - 7 August 2003. 15 August 2003. (http://www.who.int/csr/sars/country/en/country2003_08_15.pdf)
Eurosurveillance Weekly. Control of SARS in the EU: measures undertaken by member states and accession countries. Eurosurveillance Weekly 2003; 7: 030626 (http://www.eurosurveillance.org/ew/2003/030626.asp)