Will Smallpox Remain the Only Disease to Be Eradicated from the World?

Jonathan Gornall

AFP Photo: Tony Karumba

This month in Abu Dhabi health experts gathered for the second biennial Reaching The Last Mile Forum, an initiative launched in 2017 with the ambitious aim of ridding the world of the diseases that cause so much suffering for so many. Frontline public health workers were praised, tens of millions of dollars pledged in support of their invaluable work and a new Global Institute for Disease Elimination was launched. Speedy results seem unlikely, however.

The expression “Reaching the last mile” captures perfectly the essence of the task that has defeated the world’s best medical brains for generations and to which Abu Dhabi has boldly committed itself. It is true that some progress has been made in the war on the 20 neglected tropical diseases targeted by the World Health Organization. Between 2010 and 2017 the number of people afflicted by these diseases, mainly in sub-Saharan Africa and Southern Asia, fell from 2 billion to 1.5 billion and the number of deaths of children under five dropped from 9.8 million a year to 5.4 million. But reducing the rate of infection of such diseases is one thing. Eradicating them entirely is quite another. In fact, it has happened only once.

It is 39 years since the WHO declared the world was free of smallpox after a 30-year international effort to defeat a deadly scourge that had blighted humankind for more than 3,000 years. But since 1980, not a single other disease has been vanquished.

Among the WHO’s 20 targeted diseases are several that for years have teetered on the edge of eradication but which have clung on tenaciously. Take dracunculiasis, better known as Guinea worm disease, an infection caused by the waterborne parasite dracunculus medinensis. The worm grows inside the body before eventually emerging through the skin, causing agony and often leaving its victim with a disabling infection.

The good news is that since 1995, 199 countries, territories and areas have been declared free of transmission and in 2018 only 28 cases were reported – one in Angola, 10 in South Sudan and 17 in Chad. The bad news is that in 2012 it was realized that the parasite was taking up residence in dogs, particularly in Chad, Ethiopia and Mali, complicating efforts to eradicate it. So far this year, at least 36 human cases have been reported, mainly in Chad.

In February, the WHO called for “renewed commitment” to addressing the ‘”last mile challenges” toward eradication of Guinea worm disease. The charitable Carter Center announced a US$40 million campaign, offering to match donations. The first organization to respond was Alwaleed Philanthropies, a Saudi Arabian foundation which donated the initial US$1 million. The Who director-general, Dr Tedros Adhanom Ghebreyesus, declared the world was “standing on the threshold of a historic achievement, eradicating the first parasitic infection and, possibly, the second human disease.”

Possibly. But we have been here before. Dracunculiasis is the epitomy of an intractable disease. As the medical journal, The Lancet, noted in a doleful editorial last February, deadlines for the eradication of Guinea worm disease “have come and gone without success.”

The World Health Assembly, the decision-making body of the WHO, first targeted the disease in 1991 for eradication within four years. Deadlines in 2009 and 2015 were also missed and it seems all but certain that Guinea worm disease will still be around beyond the end of 2020, the most recent date set for its extermination. The Lancet concluded that eradication “is, at best, many years away [and] at worst, simply a pipe dream.”

The survival of any disease depends upon constantly shifting geographical, social, political and cultural variables. For example, deaths from measles, a disease identified decades ago as ripe for eradication, fell from 550,100 in 2000 to 89,780 in 2016. But in 2016 around 7 million people, mainly in Africa and Asia, were still infected by a disease which – thanks to false anti-vaccination propaganda – is even making a comeback in developed nations.

Malaria is another tenacious disease. In 2017, more than $3 billion was spent on eradication efforts, yet the number of cases actually increased, from 217 million to 219 million. Malaria killed around 435,000 people in India and 10 countries in sub-Saharan Africa.

The last person known to have been infected with naturally occurring smallpox was Ali Maow Maalin, a Somalian, in 1977. He survived but with tragic irony, he contracted and died from malaria while working as a vaccination volunteer during Somalia’s 2013 campaign against polio.

Scientists remain encouraged by the defeat of smallpox. But it is still the only disease to have been eradicated by unified global action and it was only achieved 175 years after the discovery of a vaccine. The economic benefit of defeating smallpox was inarguable. The cost of the international campaign against the disease in the entire decade before its eradication was about $300 million, compared to the annual burden on the global economy of $1.35 billion. Nonetheless, even after defeating smallpox, the authors of the WHO’s official account of that battle admitted in 1988: “The prospects at present for the global eradication of most human diseases are not good.”

That gloomy prognosis remains true, even for the three diseases the authors nominated 31 years ago as the most likely candidates to go the way of smallpox: measles, polio – and Guinea worm disease.

Jonathan Gornall is a British journalist, formerly with The Times, who has lived and worked in the Middle East and is now based in the UK.