SARS – Killer Bug

Kate Roach

April 2003

Day by day new cases of SARS infections are turning up, as the virus expands its deadly circle. Are we witnessing the beginnings of the next global epidemic, or is the disease likely to burn itself out in isolated communities? The experts cautiously err towards a burn-out, but warn that unless stringent infection controls are in place the virus just might explode out in to pandemic proportions.

What is SARS?

The initial symptoms of SARS (severe acute respiratory syndrome) are similar to flu. They include a high fever (over 38ºC), dry cough and shortness of breath. The problem is that these symptoms are common to a number of flu and cold viruses that are in regular circulation. So don't panic, unless you've been in close contact with someone who has been diagnosed with SARS, or you have recently travelled to areas reporting SARS cases (see World Health Organisation website in resources below). Other symptoms sometimes present are headaches, muscular aches and pains, loss of appetite, rash and diarrhoea.

The World Health Organisation (WHO) issued a global health alert about SARS on 12 March 2003. With lightening speed, and the close collaboration between 13 laboratories around the world, it took just five weeks to identify the virus. The consensus from participating labs is that SARS is caused by a member of the coronavirus family, never before seen been in humans. Coronaviruses are usually associated with the common cold, clearly this new one is far more serious. WHO and the network of labs working on SARS have dedicated their work to Dr Carlo Urbani, the WHO scientist who first alerted the world to the presence of SARS in Hanoi, Vietnam, and who died from the disease in Bangkok on 29 March 2003.

It is too early to say where SARS came from, but there is speculation that it arose in China and that it's of animal origin, as are many of the viruses we humans harbour. In a way the question of its origin is academic, but the identification and characterisation of the virus will facilitate work on vaccines and therapies that are effective against infection. A diagnostic test is already on the way, which will be a boon to health professionals trying to sort cases of common flu from SARS. Vaccines and therapies remain months or years away as yet and until they are available a key question for WHO and collaborating scientists is the mode of infection. Understanding how the virus is transmitted from one person to another is vital if the virus is to be controlled.

Transmission of SARS

Coronaviruses are usually transmitted through contact with body fluids or respiratory secretions from infected people. Breathing in someone's cough or touching anything that they have inadvertently coughed onto could give you a dose of their viruses. The current consensus is that SARS transmits in this way and that this mode of transmission requires very stringent infection controls, like quarantine, curbs on travel and school closures. Having said that, SARS is not as highly contagious as the flu virus. Many experts working in the field of virology breathed a sigh of relief when the news broke that SARS was not caused by the flu virus.

Professor John Oxford, virologist at St Barts and Royal London Hospital, explains: 'You can pick flu up just by sitting next to someone, you know, it's explosive, explosive, explosive. Compared to that the virus causing the current SARS outbreak, looks much less infectious.'

So far, most cases of SARS have been restricted to family groups and health workers in hospitals who are in very close contact with infected patients. 'That's the classic signal that a virus of fairly low infectiousness gives, that it can spread under particular circumstances but does not have the beef, the oomph, to explode out into the great wider community,' says Professor Oxford. He remains relatively sanguine about the current outbreak: 'If it were highly infectious [like flu], the thing would have run around the world by now, it really would. So here is a virus that, I think, gives signs, certainly at the moment of being able to be contained.'

SARS has moved around the world, by virtue of air travel, but the vast majority of countries reporting outbreaks of SARS are dealing with a small number of imported cases. Where these cases have been promptly reported to health authorities and managed with high standards of infection control, further spread to family members or care staff either doesn't occur at all or is reduced to a small number of infections.

Having said that, there is a concern, issuing from Hong Kong that the SARS virus may have another means of spreading. A large and sudden cluster of nearly simultaneous cases attacked 321 residents of a housing estate called Amoy Gardens in Hong Kong. The sudden appearance of so many cases at once suggests the possibility of an environmental source of infection. Added to that, the Amoy Gardens cluster has some disturbing features. These patients seem to have contracted a more severe disease, around 20% of them required intensive care against 10% of other SARS patients, and deaths are occurring in younger, healthier people. Around 66% of Amoy Gardens patients presented with diarrhoea, compared with 2-7% in other outbreaks.

Speculation centres around the fact that coronaviruses mutate frequently – Amoy Gardens may represent a new extra-virulent form. alternatively these cases may result from infection with higher viral loads – a situation that has been observed in other situations following exposure to an environmental source of a disease agent. The Amoy Gardens cluster of SARS is still under investigation, but the virus has been detected in the faeces of infected patients. And so, it's suspected that the sewage system may have been the means by which the virus spread so rapidly through the housing estate, but this theory has yet to be confirmed.

The good news

Since the 1940s, WHO have had an intense focus on infectious disease. Their Department of Communicable Disease Surveillance and Response (CSR) creates global partnerships of scientists and health professionals who together report, contain and investigate disease outbreaks. The partnerships are based on the 1949 World Health Assembly policy that WHO would not establish international laboratories itself, but would assist and coordinate the activities of existing national institutions and laboratories. There are over 150 collaborating centres and laboratories worldwide in close partnership with CSR who work to minimise global threats from all epidemic-prone, emerging and drug-resistant infections.

If it weren't for the coordinating activities of WHO, it's quite likely that we in the UK still wouldn't know about SARS. Certainly, the viral agent wouldn't have been identified and characterised so quickly and infection controls would not have been put in place so rapidly around the world. If and when SARS is contained all credit should be given to WHO and their collaborating teams of scientists. It is thanks to WHO that we can breath a little more easily in the face of other more serious, more infectious agents that are bound to crop up in the future.

Professor Oxford studies flu epidemics, he is particularly interested in the circumstances that created the 1918 flu pandemic, arguably the most devastating pandemic in history. He, along with WHO, are well aware that flu of this severity is likely to strike again, but he's encouraged by the response of the international community to the recent SARS outbreak:

Read more about Professor John Oxford's work and the flu pandemic of 1918.

Find out more

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Websites

Bird Flu
A flurry of media hysteria about a forthcoming killer flu pandemic has sent the nation dashing down to the docs. What are the facts? Are we right to be worried?

The Spanish Flu of 1918
The flu virus of 1918 killed up to 100 million people worldwide. What made it so lethal? Virologists say it's vital to answer this question if we are to avoid another deadly pandemic.

WHO – SARS
www.who.int/csr/sars/en/
The WHO website carries up-to-date information on affected areas, travel advice, symptoms and science.

Chinese Embassy in the UK
www.chinese-embassy.org.uk/eng/index.html
Information on how the Chinese Government is tackling the outbreak. There is speculation that the disease originally arose in China.

Department of Health
www.doh.gov.uk/sars/index.htm
This page provides links to the latest UK travel advice for those going to or returning from areas that may be affected by SARS.

1918 Flu Pandemic
www.vortex.is/~sigrun
Extensive directory of links to sites about the 1918 flu pandemic when over 50 million people died worldwide.

Guardian Obituary: Dr Carlo Urbani
http://education.guardian.co.uk/higher/
news/story/0,9830,940660,00.html
Obituary of the man who helped to identify the SARS virus. He too became a victim.

New Scientist
www.newscientist.com/hottopics/sars
A wide range of readable scientific information on the virus, including background information and the latest news, features and analysis.

Public Health Laboratory Service
www.phls.co.uk/topics_az/sars/
public_page.htm
Part of the UK's new Health Protection Agency, the site contains SARS information, guidance and health alerts for the United Kingdom.

The Guardian: 'China says SARS outbreak is 10 times worse than admitted'
http://society.guardian.co.uk/publichealth/
story/0,11098,941062,00.html
News story reporting the Chinese Government's SARS cover-up. Officials later conceded that 'the problem in Beijing was nearly 10 times worse than had been admitted'.

The Center for Infectious Disease Research and Policy at the University of Minnesota
www.cidrap.umn.edu/cidrap/content/
hot/sars/news/apr1503sars.html
Report on the genetic sequencing of the SARS virus, which should lead to the improvement of diagnostic tests and the development of treatments and vaccines.

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