The new strain of so-called swine flu has arrived in Britain from Mexico - with two confirmed cases in Scotland.
If - and it is still a very big if - swine flu turns into a pandemic, it won’t be the first time an outbreak of flu has caused mayhem across the world. The 1918 Spanish flu pandemic infected around a third of the world’s population, killing at least 50 million people. At the outset, few realised quite how lethal the so-called Spanish Lady would prove. It wiped out whole families, including many men who'd survived the dangers of the First World War trenches.
Dr Colin Russell, who's Head of Epidemiology at the Centre of Pathogen Evolution at the University of Cambridge explains how pandemics normally evolve from a virus which uses animal-to-human transmission - whereas "normal" seasonal 'flu is spread from person-to-person - and only affects a small proportion of the population every year - estimated to be around 10%. Seasonal 'flu infects many millions of people - and kills up to half a million people every year. Because humans aren't normally exposed to the "animal" verisions (mostly from birds or pigs) they don't have any of the natural immunity which they do have to the solely-human strains. This is why pandemics can cause so many deaths.
Dr Brian McCloskey, who's the Director of the London region of the Health Protection Agency explains how the alert status in the UK has risen from 3 to 4. A full-scale, confirmed pandemic would take us to level 6. He explains about the stocks of antiviral treatments would be distributed if there was a pandemic. He explains how good hygiene is essential in stopping the spread of 'flu - disposing carefully of used tissues, washing hands and surfaces and staying at home instead of going to work can all help reduce the spread of 'flu. There is no vaccine for the Mexican strain - but the scientists hope that the regular 'flu vaccine may provide some protection if people are infected with this new strain.
The Habditch family, who live in Gloucestershire, fell ill after a cruise along the Mexican coast. Once they got home and read the headlines about the deaths in Mexico from swineflu, they rang their GP as 15 year old Grace had symptoms of 'flu - including a sore throat and neck. The doctor visited their house - wearing a mask and protective clothing - and took swabs. The next day the tests came back clear and their quarantine was lifted.
At the moment the tests to identify 'flu strains have to be carried out in special laboratories. But Dr Alan McNally, who's a senior lecturer at Nottingham Trent University, is part of a European team working on portable testing equipment that can identify the virus in just 25 minutes. This test could be carried out in the patient's home and Dr McNally says his team have redoubled their efforts to make the test available, given the current situation.