At least 26 people have died as a fresh outbreak of Ebola grips the Democratic Republic of Congo. What began as a handful of cases in rural areas has now reached the city of Mbandaka - where it could spread even faster. Nine countries on Congo's border are on high alert.

Ebola is incredibly deadly and contagiousSpreads from one organism or person to another. . Those infected suffer a high fever, vomiting, diarrhoea, and internal bleeding - around 50% of cases end in death.

Between 2013 and 2016, a vicious epidemic ravaged several West African countries, killing 11,310 people. Cases were even recorded in Britain and the US.

So far, this latest flare-up is yet to be classified as a global health emergency.

And this time doctors have a brand new weapon: an experimental vaccine. Not available during the 2013 outbreak, it has proven effective in recent trials. Dr. Daniel Lucey thinks it may become a "game changer" in preventing Ebola epidemics full stop.

If this is the case, it would contribute to a global trend which sees doctors slowlyAccording to the World Health Organisation (WHO), 16 million people died from infections in 1990. This fell to 15 million by 2010, and is projected to fall to 13 million by 2050 - in spite of increases in the global population. winning the war against infectious diseases. Global deaths from tuberculosis have been slashed by 37% since 2000, and deaths from AIDs have almost halved since 2005.

And with modern drugs and sanitation, it is surely impossible for the 21st century world to suffer pandemicsWhen a disease spreads across an extremely large area, or the entire world. A pandemic is more severe than an epidemic. on the scale of the Black Death or Spanish fluThe Black Death was a plague pandemic which killed between 75 and 200 million people during the 14th century. Spanish flu killed around 50 million people between 1918 and 1920. - both of which killed tens of millions.

Or so you might think. Medicine is improving, but grand changes in how we live may actually be increasing the risk of pandemic outbreaks.

For example, more people than ever now live in cities; the United Nations predicts that 66% of the world will live in urban areas by 2050. As more people are squeezed close together, disease has more chance to thrive.

Secondly, the increased risk of flooding that climate change brings may spread waterborne diseases like cholera more widely.

Then there is tourism. In 2017, there were 1.3 billion tourist arrivalsAccording to the World Tourism Organisation. across the world - every flight a potential vehicle for pathogens to spread across borders.

It is possible, some argue. And if this vaccine works, it will be the latest example of the power of modern medicine. It stretches beyond science too. Sanitation in developing nations has improvedAccording to a 2015 WHO report, 91% of the global population uses an improved drinking water source, up from 76% in 1990. remarkably in recent decades, and access to health care has been boostedAccording to a 2017 report published in The Lancet, access and quality to health and quality to health care improved in almost every country in the world between 1990 and 2015. the world over. Progress will bring an end to pandemics.

But progress also brings greater dangers, others respond. For example, antibiotics have saved millions, but they also help drug-resistant superbugs to evolve. Air travel and modern megacities may connect more people, but they also provide the perfect place for diseases to thrive. Pandemics are our future, not the past.