Sars and the UK: What are the risks?

Sars checks at airports have been introduced

The government has been accused of not doing enough to prevent Sars from becoming a serious problem in the UK.

Other experts suggest that the impact of the infection could be greater than HIV.

But what are the present risks to UK citizens from this new illness?

Sars is undoubtedly a major public health problem in China, Hong Kong and Canada, where there have been hundreds of deaths and thousands of cases.

Efforts to tackle the disease in these places have not yet halted its spread.

Sars cases in the UK March 19: A London man treated at Barnet Hospital after arriving on a flight from Taiwan. Discharged after specialist treatment on March 26. March 21: A man was treated at University College Hospital, London following a trip to Singapore. Discharged early April. March 23: A 28-year-old man returning from Hong Kong is treated at the Royal London Hospital. Dicharged a few weeks later. April 3: A man believed to have contracted the virus in during a meeting with a Hong Kong businessman in the UK. Discharged April 20. April 4: Essex man admited to hospital in Chelmsford following a trip to Tiawan. Released April 11. April 5: Lin Thomas admitted to North Manchester general hospital following a trip which included a stopover in Singapore. Remains in quarantine at home.

And there are fears that people travelling from the Far East to the UK could spark a major outbreak here.

So far, however, this has failed to materialise in the UK.

There have been only six "probable" cases in the UK, and no-one has yet died from the illness.

England's Chief Medical Officer Sir Liam Donaldson said that cases had been "spotted quickly" and dealt with.

All the cases concerned people who had recently returned from Sars outbreak areas such as China and Hong Kong.

The UK is fortunate to have one of the most advanced disease surveillance systems in the world.

Finding cases

Not only is there a set procedure which doctors can use to report suspected cases, but the UK has a network of doctors skilled in "contact tracing" - designed to find and isolate people who have been in contact with an infectious disease victim.

Your chances of being sneezed on by the wrong person in the Tube are vanishingly small - you're more likely to be knifed for your wallet Professor Richard Tedder, University College London

Infectious disease experts here are confident that the UK can cope if it is threatened by a large number of cases.

A WHO spokesman said that a "single infected individual" could cause chaos by infecting hospital staff and relatives.

He said: "What is important is the early idenfication of cases. Otherwise, the disease can dig into the community.

"It's important that people know what the symptoms of Sars are."

However, he said: "We are still confident that this is a disease which can be contained and eradicated."

Tiny risk

We are still confident that this is a disease which can be contained and eradicated Dick Thompson, WHO

While it is conceivable that an individual in the UK could pick up the illness by coming into contact with someone has arrived from the Far East carrying it, experts say that this is incredibly unlikely.

Professor Richard Tedder, from University College London, said: "Your chances of being sneezed on by the wrong person in the Tube are vanishingly small - you're more likely to be knifed for your wallet."

However, he added: "That is where we stand in the third week of April - but things could be different in the third week of June.

"We live in a cottage environment in the world - someone's problem in Hong Kong today could be our problem tomorrow.

"It's only going to be matter of time before the virus starts transmitting in this country."

The likely spread of the infection is dependent on several factors, among them the ability of the virus itself to be transmitted, and the ability of health systems to pick up cases early.

How contagious?

However, what scientists don't know for sure is at what point a Sars patient is capable of spreading the disease.

Air travel has allowed the swift spread of the illness

If he or she is contagious before symptoms appear, the illness is far more likely to spread quickly, although the WHO says there is no evidence at present that this can happen.

Because experts still know relatively little about this new illness, some are convinced that it has the potential to become more significant than HIV.

Dr Patrick Dixon, who specialises in predicting "global trends", told the BBC that the illness was of particular concern in developing countries, which have neither the infrastructure nor the medical facilities to cope with a large scale Sars outbreak.

But there is no current vaccine, nor any swift prospect of one, and antiviral treatments have had only partial success.

While the NHS might expect to cope with a surge in Sars cases, developing countries might not be so well equipped to deal with the illness.

Dr Dixon said: "This is an illness that needs to be taken extremely seriously."