Wednesday, June 29, 2011

Rinderpest, Scourge of Cattle, Is Vanquished

On Tuesday in a ceremony in Rome, the United Nations is officially declaring that for only the second time in history, a disease has been wiped off the face of the earth.
The Takeaway: Donald McNeil Talks About Rinderpest
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G. R. Thomson

FIELD OF DEATH Cattle carcasses littered a pasture in South Africa in 1900 during a rinderpest epidemic.
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The disease is rinderpest.

Everyone has heard of smallpox. Very few have heard of the runner-up.

That’s because rinderpest is an epizootic, an animal disease. The name means “cattle plague” in German, and it is a relative of the measles virus that infects cloven-hoofed beasts, including cattle, buffaloes, large antelopes and deer, pigs and warthogs, even giraffes and wildebeests. The most virulent strains killed 95 percent of the herds they attacked.

But rinderpest is hardly irrelevant to humans. It has been blamed for speeding the fall of the Roman Empire, aiding the conquests of Genghis Khan and hindering those of Charlemagne, opening the way for the French and Russian Revolutions, and subjugating East Africa to colonization.

Any society dependent on cattle — or relatives like African zebu, Asian water buffaloes or Himalayan yaks — was vulnerable.

As meat and milk, cattle were and are both food and income to peasant farmers, as well as the source of calves to sell and manure for fields. Until recently, they were the tractors that dragged plows and the trucks that hauled crops to market. When herds die, their owners starve.

The long but little-known campaign to conquer rinderpest is a tribute to the skill and bravery of “big animal” veterinarians, who fought the disease in remote and sometimes war-torn areas — across arid stretches of Africa bigger than Europe, in the Arabian desert and on the Mongolian steppes.

“The role of veterinarians in protecting society is underappreciated,” said Dr. Juan Lubroth, chief veterinary officer of the Food and Agriculture Organization of the United Nations, at whose headquarters Tuesday’s ceremony is being held. “We do more than just take care of fleas, bathe mascots and vaccinate Pooch.”

The victory is also proof that the conquest of smallpox was not just an unrepeatable fluke, a golden medical moment that will never be seen again. Since it was declared eradicated in 1980, several other diseases — like polio, Guinea worm, river blindness, elephantiasis, measles and iodine deficiency — have frustrated intensive, costly efforts to do the same to them. The eradication of rinderpest shows what can be done when field commanders combine scientific advances and new tactics.

In 1998, a longtime leader of the effort, Sir Gordon R. Scott of the Center for Tropical Veterinary Medicine at the University of Edinburgh, wrote an article saying he had reluctantly concluded that it would fail.

“The major obstacle,” he wrote, “is man’s inhumanity to man. Rinderpest thrives in a milieu of armed conflict and fleeing refugee masses. Until world peace is secured, the nays win the argument.”

He cited Somalia, Sudan, Sri Lanka, Yemen and Kurdish parts of Iraq and Turkey as areas where war drove animals and their owners over borders and life was risky for vaccinators.

Dr. Scott will not be in Rome for the ceremony; he died in 2004. Yet perhaps without realizing it, he did outlive rinderpest. The last known case was in a wild buffalo tested in Mount Meru National Park in Kenya in 2001.

An Ancient Battle

The modern eradication campaign began in 1945, when the Food and Agriculture Organization was founded. But it became feasible only as vaccines improved. An 1893 version made from the bile of convalescent animals was replaced by vaccines grown in goats and rabbits and finally in laboratory cell lines; a heat-stable version was developed in the 1980s.

How long the ancient battle went on is uncertain. Although cattle die-offs did affect all the historical events mentioned above, there is uncertainty about which were from rinderpest and which were something else, like anthrax.

Death from rinderpest is rapid and nasty. Animals get feverish; their eyes and noses run. Their digestive tracts are inflamed from mouth to anus, and they die of diarrhea and protein loss.

But other diseases have overlapping symptoms, and a rapid diagnostic test that could be used next to a dying animal was not developed until the 1990s.

Until recently, it was assumed the disease existed as long ago as 10,000 B.C., when cattle were domesticated in the Indus Valley in what is now Pakistan. It was blamed for an epidemic in Egypt in 3,000 B.C. (the fifth plague of Moses fell on the pharaoh’s herds) and for the widespread die-offs that starved the Roman Empire in the face of fourth-century invaders. In the ninth century, it was the chief suspect in the “mortality upon the horned animals” in the British Isles.

Last year, however, Japanese geneticists studying rinderpest’s mutation patterns estimated that until about A.D. 1000, it was virtually identical to measles — making it likely that pandemics that killed only animals before that time had other causes, like anthrax or possibly an ancestor virus from which both measles and rinderpest evolved.

Some experts now believe the disease arose in the gray oxen of the Central Asian steppes and was swept forward in the trains of baggage and beasts that followed the Mongol armies in the 1200s as they conquered Eurasia from China to Poland. (The Mongols are also suspected of importing bubonic plague from South Asia in flea-bitten rats hiding in grain sacks.)

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