In only the second elimination of a disease in history, rinderpest — a virus that used to kill cattle by the millions, leading to famine and death among humans — has been declared wiped off the face of the earth.
Rinderpest, which means “cattle plague” in German, does not infect humans, though it belongs to the same viral family as measles. But for millenniums in Asia, Europe and Africa it wiped out cattle, water buffalo, yaks and other animals needed for meat, milk, plowing and cart-pulling.
Its mortality rate is about 80 percent — higher even than smallpox, the only other disease ever eliminated.
“This is something the entire global community can be proud of,” said Dr. William R. White, director of the United States Department of Agriculture’s foreign animal disease diagnostic laboratory on Plum Island, N.Y. “Rinderpest has caused almost unimaginable misery for a very long time.”
The last case was seen in Kenya in 2001. On Thursday, the United Nations Food and Agricultural Organization announced that it was dropping its field surveillance efforts because it was convinced that the disease was gone. The official ceremony in which the World Organization for Animal Health will declare the world rinderpest-free is scheduled for May. (That organization, known as the O.I.E. for its initials in French, was created in 1929 chiefly to fight rinderpest.)
“This has been a remarkable achievement for veterinary science, evidence of the commitment of numerous countries,” the Food and Agricultural Organization said in its statement.
Still to be decided is how much virus to keep frozen in various countries’ laboratories, along with tissue from infected animals and stocks of vaccine, which is made from live virus. Virologists like to have samples handy for research, but public health experts, fearing laboratory accidents or acts of terrorism, usually press to destroy as much as possible. The smallpox virus is officially supposed to exist only in two lab freezers, one in Atlanta and one in Moscow.
Rinderpest is thought to have originated in Asia and spread through prehistoric cattle trading; it was in Egypt 5,000 years ago. It never became established in the Americas (though there was a small outbreak in Brazil 90 years ago), nor in Australia or New Zealand. Cattle infected with it would have started dying aboard ship and the herd would be slaughtered or quarantined on arrival.
But it reached Africa in the late 19th century, with devastating consequences. The near total destruction of herds meant widespread famines; in one of those, a third of the population of Ethiopia died, according to the Food and Agricultural Organization.
It was apparently introduced to Abyssinia, which is now Ethiopia, in cattle from India imported by the Italians during their campaign to conquer Abyssinia, said Dr. Jeffrey M.B. Musser, a rinderpest expert at Texas A&M’s veterinary school. Some experts believe it was deliberate, as a form of biological warfare, he said, while others contend that it was accidental.
It also infected game animals, like giraffes and antelopes, but did not kill as many of them.
For centuries, cattle owners and local veterinary officials fought the disease with slaughter, quarantine and crude immunization efforts. As with smallpox, many tried “inoculation” — cutting open the skin and introducing pus or tissue from infected animals, sometimes treated with heat or chemicals, hoping to cause minor infections that would create immunity. But these efforts sometimes just spread the disease.
Then in the 1950s, Walter Plowright, a British veterinary pathologist working in Africa, developed a successful vaccine using live, weakened virus produced with the same cell-culture techniques pioneered for polio.
The global effort to eliminate rinderpest was officially begun in 1994. It relied on the vaccine and a network of field agents and laboratories that could hunt for and confirm outbreaks.
Nine years passed between the last known case and this week’s de facto declaration that the disease was gone, but such timelines are typical in disease eradication. Many diseases resemble one another, and the authorities need both time and frequent blood testing to be sure one is really gone. The last case of smallpox was seen in Somalia in 1977, but the disease was not declared eradicated until 1980. (In April, there was a brief scare in Uganda when doctors reported a new case; it turned out to be chicken pox.) Veterinary diseases need longer surveillance; while mothers will carry sick children many miles to a doctor, herders often just have to let animals die.
The virus that caused a worldwide outbreak in 2002 of SARS, or severe acute respiratory syndrome, was effectively contained by mid-2003. The last known case, caused by a lab accident, occurred in 2004, but SARS is not considered eliminated because it is assumed to persist in bats, wild civets and perhaps other animals, and could return.