Humanity is locked in a millennia-old battle to the death with diseases. The current outbreak of Ebola reminds us that as our cities get bigger and international travel easier, the risks in an outbreak grow even higher

The Black Death swept into Europe on boats from the East in the 14th century, killing as much as half the population of the continent, somewhere between 75 and 200 million people worldwide.



The Spanish flu of 1918, carried around the world by soldiers bound for or returning from the butchery of Europe’s battlegrounds, killed between 50 and 100 million people – many more than died in the First World War itself, and maybe more than have died in any war.

Humanity is locked in a millennia-old battle to the death with diseases like these. We have fought them back with herculean effort. We developed penicillin and other antibiotics to treat bacteria like the ones thought responsible for the Black Death, and vaccines to fight viruses.

But we are in an arms race. And while our ability to treat disease is better than ever before, the current outbreak of Ebola, and the first diagnosis of the virus outside of Africa, is reminding us that as our cities get bigger and international travel becomes easier, the risks involved in an outbreak grow ever higher. We are, as Mark Woolhouse, a professor of infectious disease epidemiology at the University of Edinburgh, says, “in a perfect storm for viral emergence.”

Ebola is very unlikely to become the next Black Death

Though Ebola has a high fatality rate when contracted, it is not the thing that keeps most epidemiologists up at night. It could theoretically become pandemic – that is, an out-of-control global epidemic – but experts say that is unlikely.

Christophe Fraser, a professor of epidemiology at the medical research council center for outbreak analysis at Imperial College, London, described four factors that are crucial in determining how severe an epidemic will be: how easily the disease is transmitted; how feasible it is to develop a vaccine and a treatment; how long before symptoms are visible the patient is infectious; and the severity of the disease – what proportion of people who contract it die.

Facebook Twitter Pinterest Praying for relief from the bubonic plague – also known as the Black Death. Photograph: Hulton archive /Getty

“Obviously if a virus is worse on all those scales,” he said, “that makes for a worse scenario. Ebola is very high on severity, and very low in terms of mode of transmission.” Ironically, this makes it safer – a disease that killed a smaller percentage of those who contract it but was more easily spread could reach and ultimately kill many more people.

Ebola is very unlikely to become the next Black Death. But that doesn’t mean something else won’t. Even with modern medicine, we haven’t rid ourselves of pandemics; indeed, they have sprung up far more recently than 1918. HIV/Aids is the most recent truly devastating pandemic – and H5N1 avian flu was even more widespread, though less deadly.

Ebola is very high on severity, and very low in terms of mode of transmission

There are many nightmare scenarios, according to Robert G Webster, chair of the virology division at St Jude children’s research hospital. “Just imagine if the Ebola outbreak in West Africa was transmitted by aerosol. If flu was just as lethal. If H5N1 [avian flu] was as lethal in humans as it is in chickens – and studies have shown that it only takes about three mutations to make it highly lethal. It’s not out of the realms of possibility.”

Fraser said that pandemics are extremely difficult to predict because they all start from a random event: a pathogen crossing to humans from another species. “The initial change, the transition, that’s where the pathogen sets in motion its change of transmission,” he said. “There are outbreaks of all kinds of strange viruses that come from contact between animals and humans; one in a million will give rise to a starting pandemic.”

That moment, he said, when the virus is learning to propagate in a new kind of host, is when much of its genetic mutation happens – after that, its evolution is much slower. The real danger is a brand new virus, or a hybrid of several (HIV is a combination of four viruses), rather than an evolution of one which, like Ebola, is already known to humans.

Facebook Twitter Pinterest ‘There have been three major [influenza] pandemics, and a mild one three years ago – which doesn’t reduce the possibility of a pandemic happening,’ Ran Balicer said. Photograph: Darron Cummings/AP

Ran Balicer, director of the infectious diseases track in the public health department of Ben Gurion University in Israel, thinks that the most likely candidate for another pandemic is a strain of influenza. “It is always on the horizon, and is a devastating scenario,” he said. “It has a good possibility of manifesting in our lifetime; there have been three major pandemics, and a mild one three years ago – which doesn’t reduce the possibility of a pandemic happening.”

Primary responders

“Flu mutates all the time, that’s the trouble,” said Webster, whose research specialty is influenza. He said he thinks the US is better-prepared for a global pandemic than it used to be.

But there are no guarantees.

The US has many advantages in combating the spread of diseases. Near-universal literacy, television and internet penetration mean reliable information about how to deal with an outbreak is much more easily disseminated to those who need it. The lack of these has greatly hindered efforts to fight Ebola in West Africa, where local customs and superstitions – including traditions surrounding the treatment of dead bodies – have made it easier for the virus to spread.

In West Africa, no one was prepared for Ebola

Additionally, US pharmaceutical companies are contracted to create a constantly updated bank of seed-stock for vaccines every time a new strain of a virus like influenza is discovered, which allows lots of doses of vaccine to be made in a short time if an outbreak occurs.

According to Ben Knowles, a spokesperson for the Centres for Disease Control and Prevention (CDC), as long as an outbreak remains outside the United States, the organisation in charge is the World Health Organisation. When a new outbreak occurs in the US – such as the patient in Texas infected with Ebola – the first point of control is the individual state governments. “They are the primary responders,” Knowles said.

When a disease on US soil spreads to multiple states, as happened with H5N1 avian flu, then the federal government takes over using the Incident Command Structure, a complex mechanism of interlocking agencies including Fema, the CDC, the Department of Homeland Security and others – the same mechanism that is triggered in the event of a natural disaster or terrorist attack.

People wear masks on the streets of Hong Kong following the outbreak of Sars, in March 2003. Photograph: Peter Parks/AFP/Getty Images

That mechanism has not been activated by the Ebola diagnosis given to Thomas Eric Duncan, the patient in Dallas. The CDC is in the area, rather, because it was invited by the state authorities in Texas to send a team to help.

The only question is: will we experience a mild disease, or a devastating disease like in 1918

But there are issues with American preparedness. A 2014 report by the Department of Homeland Security with the ominous title “DHS Has Not Effectively Managed Pandemic Personal Protective Equipment and Antiviral Medical Countermeasures” found that the DHS “did not adequately conduct a needs assessment prior to purchasing pandemic preparedness supplies and then did not effectively manage its stockpile of pandemic personal protective equipment and antiviral medical countermeasures.”

Its authors discovered that, among other things, 84% of the department’s store of hand sanitiser was expired – some as much as four years out of date – and that 81% of the department’s antiviral medication would expire by the end of 2015. To solve this problem, the department is “applying for a shelf-life extension with the Food and Drug Administration” for the influenza drug Tamiflu.

Fraser said that the current outbreak of Ebola has shown that the global systems that are supposed to spot outbreaks of diseases are not good enough, “and more importantly, the action that follows is not fast enough, not coordinated enough, to cut off an epidemic at source. We know it’s possible – one of the triumphs of the last few decades was the containment of Sars,” he said. “But we failed to achieve that in the case of Ebola.”

Webster agreed. “In West Africa, no one was prepared for Ebola,” he said. “We are better off for flu; we can be prepared more quickly. But still if something like Ebola was to spread rapidly, there wouldn’t be the resources in the world. You have to have the equivalent of a police force to deal with it.”

“Once every few years we see a new disease in humans,” said Balicer. “Over and over again, we see examples of new diseases; Sars, Aids, mad cow disease. You see, in a pretty constant manner, new pathogens emerging, and we can expect this trend to continue.”

“It’s an example of rolling the dice,” he added. “The only question is: will we experience a mild disease, or a devastating disease like in 1918?”