Friday 19 January 2018

Ebola: The deadly disease that just won't go away

As the Ebola epidemic sweeps Africa, we report on our ceaseless struggle with deadly germs.

Microscopic view of Ebola virus (EBOV).
Microscopic view of Ebola virus (EBOV).
Outbreak: Medical staff treat an Ebola victim in Sierra Leone

Damian Corless

Irish travellers planning to visit Africa in the near future are being urged to do a rethink in the light of an outbreak of the deadly Ebola virus which has been declared the worst ever. To date over 900 people have died in the west African states of Nigeria, Sierra Leone, Guinea and Liberia.

The virus is transmitted through contact with the bodily fluids of carrier animals, and kills nine out of 10 humans who become infected. The disease was first identified almost 40 years ago in 1976 but the best efforts of medical science have failed to come up with a cure. Other diseases have been with us since the dawn of civilisation, and indeed came as part of the trade-off we made when we took up farming around 10,000 years ago.

Outbreak: Medical staff treat an Ebola victim in Sierra Leone
Outbreak: Medical staff treat an Ebola victim in Sierra Leone

All the available evidence suggests that as soon as humans began domesticating animals they paid a high price in terms of their own health. The first farm livestock - cattle, sheep, pigs and goats - provided convenient meat and dairy products for the early farmers of the Middle East, but at close proximity they also transmitted a range of diseases.

The immune systems of humans have evolved resistance to these viruses over many generations, but the diseases in turn have mutated into new strains in a lethal game of leap-frog. While the peoples of the Old World developed a tolerance to the many diseases incubated in their livestock, the natives of the Americas had no such resistance and they were wiped out in their millions by the viruses carried by European invaders.

One of the diseases spread from livestock to the first farming communities was tuberculosis, which reached epidemic proportions in Ireland during the 1930s and 1940s.

Appointed Minister for Health in 1948, Noel Browne declared war on the scourge of TB, rolling out a massive screening campaign, a hospital building scheme, and a number of new vaccines including penicillin. His campaign was instrumental in virtually wiping out the airborne disease, but it made a comeback in Ireland in the late 1980s. While infection rates in Ireland today are amongst the lowest in the world, with 384 cases reported last year, TB kills millions each year in Africa and Asia.

Another deadly disease which has been with us since the dawn of recorded history is cholera, which this year will infect some three million people in the Third World, killing 130,000. Cholera is now virtually unknown in Ireland, but, in Victorian times, it stalked the land as a mass killer.

The deadly waterborne disease had been known in the Ganges Valley of India since ancient times, but, with the opening up of new trades routes in the age of sail, the pestilence suddenly swept across vast virgin territories. The second global pandemic reached Ireland in the 1830s and the third struck in 1848, at the height of the Great Famine.

With the population already weakened by disease and starvation, multitudes fell easy prey to the disease which flourished in water - particularly standing water - infected with the human, animal and vegetable waste that littered the stricken landscape. At the time, no one knew how cholera spread. Most scientific minds subscribed to the Miasma Theory, attributing the spread of the disease to 'bad air'.

English medic John Snow discovered the link between cholera and bad water in 1854, just six years after it devastated Ireland, when he linked an outbreak in London's Soho district to a particular street pump. The water source for the pump was a well next to the Thames, which bordered a leaking cesspit. Pressed by Snow, local officials removed the handle from the pump and the outbreak stopped. As Snow's idea found acceptance, there was a boom in the building of parish pumps across Ireland, providing disease-free water from untainted wells.

Microscopic view of Ebola virus (EBOV).
Microscopic view of Ebola virus (EBOV).

There is much ado right now about the centenary of the Great War, and perhaps in four years equal attention will be given to an event that killed many more than that conflict itself.

In the late autumn of 1918, as the guns fell silent, an outbreak of what was termed Spanish Flu killed perhaps 50 million people worldwide. The disease is thought to have been incubated in tight-packed, filthy, army camps and the official records show that it killed 280,000 across the United Kingdom of Britain and Ireland.

The Evening Herald speculated that the cause of the epidemic was Swine Fever caught by eating "bad bacon". Just a few years earlier the team of Robert Scott of The Antarctic put down a bout of scurvy to "tainted" tinned meat, ignorant of the fact it's caused by a lack of Vitamin C.

While others before Scott had realised that scurvy can be tackled, the common flu is something that just keeps mutating to foil every human effort at a cure. As Bruce Willis learned in the movie Twelve Monkeys, the shrinking of the Earth to a global Village exposes us to new diseases and new versions of our oldest infections.

The most recent mutation of age-old influenza to cause a global panic was Avian Flu, which had the planet's authorities in a tizzy following an outbreak from China to Turkey in 2005.

The story of human evolution and survival is the story of coming up against deadly mutations and adopting our bodies to withstand them. However, building immunity takes time. For most of human existence, the gaps between populations and much slower transport speeds allowed so called 'herd' groups to come up with a natural defence and dilute most diseases before they could pass on.

In today's crowded, fast-moving world, the prospect of isolated 'herd' groups diluting a virus are much lower and the prospects of millions dying much higher. Flu, it seems, will always be with us. If Avian Flu succeeds in swapping genes with a common human flu bug and mutates from a disease confined to poultry into a deadly human pathogen, birds will be out of the chain of infection and it will jump from human to human.

What we do have today to even up the fight are modern medicines and advance warning systems. In response to the threat of yet another flu mutation 10 years ago, which could be accelerated by jet travel, the Irish government drew up a Model Plan For Influenza Pandemic Preparedness.

The State's health agencies were circulated with a plan to be activated in the event of an emergency such as an avian flu pandemic. This plan was drawn up on the basis that we can predict certain scenarios should the flu strike Ireland. It entailed that in the event of an outbreak the authorities will move to close schools, creches, cinemas, sporting venues and some workplaces in an attempt to keep the opportunities for infection to a minimum.

But let's finish on a positive note, with the good news of humanity's decisive victory over smallpox after a battle that was cruelly one-sided for some 10,000 years.

Smallpox was one of those diseases which spread to the first farming populations in the Middle East ten millennia ago. The first victim we can be sure of was the Egyptian Pharaoh Ramses V, while it is known to have killed at least five reigning monarchs in the 18th Century.

Smallpox was a truly horrific infection, blinding and maiming those it did not kill. During the 20th Century alone, it carried off some 500 million people across the globe. In 1979, thanks to the appliance of science, it was declared eradicated.

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