The Ebola outbreak in West Africa is a major threat to many other sub Saharan countries but only a small one for the developed world, including the UK. The virus does not transmit that easily and relies on poverty and poor hygiene to infect large numbers of people.
The reason the current Ebola outbreak has evoked such fear around the world is because the disease is exceptionally severe, with a fatality rate between 50 per cent and 90 per cent, varying according to the specific strain of virus as well as age and vulnerability of the people infected. The mortality rate for the current Ebola outbreak has been running at about 60 per cent, which is close to average for the disease. By contrast the famous Spanish flu pandemic just after the First World War killed 2.5 per cent of infected people. The deadliness of Ebola has prompted a rehearsal of measures to restrict its spread if it does arrive in the UK, such as immediate quarantining of anyone even showing signs of fever, and subsequent confirmation of infection via a blood test looking for the presence of the virus’s DNA.
But despite this the current Ebola outbreak has provoked only mild alarm among relevant UK agencies such as Public Health England. This is because it lacks one key property of a truly global pandemic. Apart from virulence—a virus's fatality rate and ability to invade the host's tissues—the other principle difference between disease causing viruses is their transmissibility—the ease with which they spread between humans. The pandemic risk of a virus, or any pathogenic organism, is a product of the severity of infection and the rate of transmission. The transmission of Ebola is virtually eliminated by good hygiene practice, such as regular hand washing at appropriate places and times.
The Spanish flu ended up killing 50 million people because it rampaged around the world, with over 1 billion people being infected. It is inconceivable that the current Ebola outbreak, even if it turned into a major epidemic across Africa, will kill anywhere near this number—at the time of writing fewer than 1000 have died. Only 2000 have died from the disease in the 40 years since it first infected humans in the mid-1970s from fruit bats, which act as a reservoir for the disease and were also probably the source of the current outbreak.
In terms of transmissibility Ebola lies somewhere between HIV AIDS and flu. It spreads a bit more readily than AIDS through contact with infected people or even surfaces they have touched, not being confined to direct exchange of bodily fluids. But it cannot be caught readily via airborne droplets like flu or the common cold.
The main risk to the UK is from infected people flying in from one of the three countries affected so far, Sierra Leone, Guinea and Liberia. A likely route would be via the Nigerian city Lagos, since there are normally frequent flights between that city and the UK as well as those three countries. However, at least one African airline, ASKY, has suspended all flights to and from the capitals of Liberia and Sierra Leone in a bid to prevent the disease reaching other African countries.
If somebody with the disease did reach the UK there would be some risk of infecting others through contact or contamination. The worst outcome would probably be the emergence of a few clusters of infection that would be isolated and then die out, but it is conceivable there could be fatalities. The chance, though, of anything resembling an epidemic emerging are described as vanishingly small by just about all virologists. Given the disease’s virulence that is just as well.
