Beating the asymptote: The end of rinderpest

Here at Casa Superbug, we’re in the midst of moving 1,200 miles, so I’m a little slower reading email than I really ought to be. That’s scant excuse, unfortunately, for not noticing one of the biggest global-health stories in years. Mitigating circumstance: Almost everyone else missed it too.

The news is the effective eradication of rinderpest, a viral disease of cattle. Rinderpest does not infect humans, and even in animals it barely occurs in the Americas (or Australia or New Zealand), though until recently it was common and devastating in Africa, South Asia and the Middle East. So unless you are a large-animal veterinarian or a cattle farmer, the disease might never have been on your radar.

So why care that it is on the verge of being removed from the world? Because this marks the first time that a disease of animals has ever been eradicated — and only the second time that any disease has been eradicated at all. The first was smallpox. That was 30 years ago.

Since then, seven other human diseases have been targeted for eradication: Guinea worm (dranunculiasis), elephantiasis (lymphatic filariasis), measles, mumps, rubella, cysticercosis, and above all polio. None of those eradication programs have yet reached their target. Polio has probably come closest, at the cost of billions of dollars and undoubted millions of hours of volunteer effort — yet each time the goal seems within reach, the disease roars back again.

It has been so long since the eradication of smallpox that — I suspect — we have lost any appreciation for the effort it takes to wipe a disease from the planet. Eradication is hard, hard work. It requires that certain conditions exist, to start with: a robust lab and surveillance infrastructure, an easily-delivered vaccine, an absence of any secondary reservoir that can give the organism a refuge. (Whuch explains why tetanus, living in soil, could never be eradicated.) It takes money, time, extraordinary numbers of people and enormous amounts of political will.

More than anything, perhaps, it requires an up-front acknowledgment of what a difficult task it is going to be. We look back on smallpox, from three decades’ distance, as a historic inevitability — but the smallpox campaign wasn’t the first try at eradicating a disease, only the first successful one. There had been four campaigns before — for malaria and yaws, among others — that failed. Writing almost 20 years after the last case, Dr. DA Henderson, one of the architects of smallpox eradication (and author of the recently published Smallpox: The Death of a Disease) reflected:

…eradication was achieved by only the narrowest of margins. Its progress in many parts of the world and at different times wavered between success and disaster, often only to be decided by quixotic circumstance or extraordinary performances by field staff. Nor was support for the programme generous,whatever the favourable cost-benefit ratios may have been. A number of endemic countries were themselves persuaded only with difficulty to participate in the programme; the industrialized countries were reluctant contributors: and UNICEF… decided that it wanted nothing to do with another eradication programme and stated that it would make no contributions. … Cash donations to WHO during the first 7 years of the smallpox programme, 1967-73, amounted to exactly US $79,500.That is not per year, but the total for that entire period. (Henderson, Bulletin of the World Health Organization, 1996

At a certain point, success begins to breed success; the smallpox campaign succeeded in part because people saw that it was working. But the very last days of the campaign were exhausting. I talked to a number of the smallpox warriors for my first book and heard them describe how, time after time. they thought they were done, only to reach another village and find yet another child with the evil telltale rash. Polio now is caught in the same asymptote: The goal has been so close, for so long, and yet the gap to zero has never quite been closed. With much less fanfare, the rinderpest campaign succeeded.

It is a little shaming to admit that I never noticed how dire a disease rinderpest was, or how robust the campaign against it — which began in 1994 — turned out to be. The United Nation’s Food and Agriculture Organization said last week:

At its height in the 1920s, the rinderpest footprint extended from Scandinavia to the Cape of Good Hope and from the Atlantic shore of Africa to the Philippine archipelago, with one outbreak reported in Brazil and another in Australia.
In the early 1980s, the disease was still ravaging livestock herds around the world, with devastating epidemics hitting South Asia, the Middle East and Africa. Losses in Nigeria in the 1980s totalled $2 billion. A 1994 outbreak in northern Pakistan wiped out more than 50 000 cattle and buffalo before being brought under control with help from FAO.

Rinderpest was a lesson in the porousness of borders: It spread around the world, over thousands of years, wherever cattle were herded or traded. (It was in Egypt thousands of years ago, but was probably introduced to sub-Saharan Africa in the late 1800s by cattle bred in India but brought by Italian colonialists.) And it was an illustration of the profound social effects of epidemics: The devastation it caused in Africa, killing 90 percent of the cattle that were the basis of tribal economies, may have paved the way for the takeover and exploitation of traditional African societies by European monarchies.

So hearing the news of the eradication of rinderpest is especially heartening, not just for the animals and livelihoods that will be saved, but also for what it says about the possibility of organizing other eradication efforts for the future. In making the announcement of eradication, the FAO called it “a powerful example of what can be achieved when the international community and individual country’s veterinary services and farming communities cooperate.” That kind of cooperation will be so necessary for future eradication campaigns — not to mention changing antibiotic prescribing patterns to decrease resistance — and it is reassuring to see that, in this case, the collaboration worked so well.

Image courtesy Flickr user publicenergy under CC


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