Research

Research

Fatal Infections

… [W]e set up to sacrifice the animal and do the autopsy which was tough on all of us because we’d become so close to these remarkable animals and would feel their loss.

           —Clarence J. Gibbs, Virologist

Infecting chimpanzees with a fatal disease

In 1957, an American doctor, Daniel Carleton Gajdusek, arrived in New Guinea to study the deadly disease known as kuru—a disease unique to the Fore tribe of New Guinea.

The Fore were ritualistic cannibals who ate their dead. By 1950, 25 percent of Fore women were dying of kuru. The condition was observed in children of both sexes as well as a few adult men. A person with kuru progresses through stages of increasingly intense tremors, shivering, staggering, an inability to walk or swallow, and eventually death.

While Gajdusek studied the disease in New Guinea, he teamed up with a virologist in the United States, Clarence Joseph Gibbs, to establish what they called the Laboratory of Slow, Latent and Temperate Virus Infections. (2)

Their theory was that the cause of kuru was some form of slowly developing virus that was transmitted during the process of eating the deceased. Other deadly neurological diseases had been observed that seemed to exhibit a similar course of symptoms and brain pathology: Creutzfeldt-Jakob disease (CJD) and scrapie in sheep. Gibbs and Gajdusek set about to determine the cause of these puzzling diseases.

In 1963, Gajdusek procured a brain sample from a Fore boy who had died from kuru. He hand-carried the tissue back to the U.S. to the lab run by Gibbs. They wanted to see if an animal infected with the boy’s brain tissue would become ill.

They purchased three two-year-old chimpanzees: Daisy, “George,” and an unnamed chimpanzee. On February 17, 1963 they inoculated one of these animals, Daisy (referred to as A-1), with the tissue. (3)

On September 17, 1963, they anesthetized George (A-4), drilled a hole through his skull and injected a solution of pureed brain from the Fore boy directly into George’s cerebellum. George was very young at the time, weighing only about 13 pounds. In the ensuing months, the scientists realized George was in fact female and renamed her Georgette.

Georgette’s decline

Georgette’s first symptoms were recorded more than two years later on June 28, 1965. The record reads: “Does not appear to be as active as usual. Stays by herself in corner.”

Subsequent records read:

July 14, 1965: “Appears to have the ‘shakes.’ Trembles at frequent intervals. No sense of balance. Fell off stoop in cage. Moving around very slowly. Jaw hangs open constantly.” (4)

July 15, 1965: “Tremors continue. Fell off top of cage today.” (5)

Not long afterwards, Daisy, too, began exhibiting similar symptoms.

The scientists agreed that the clinical impression appeared to be kuru. Gibbs continued to document the painful and pitiful decline of Georgette. Throughout the chronicle, his despair over their suffering and his growing attachment to the afflicted chimpanzees is ironically apparent. He was soon nursing both Daisy and Georgette around the clock.

September 20, 1965: “I don’t know how much longer this animal [Georgette] can continue to degenerate. She is starting to appear emaciated and grossly weaker…. We fed her again by hand….” (6)

September 27, 1965: “I fed the animal by hand today; managed to get 3 apples and 3 pieces of whole wheat bread soaked in milk and cream into her….Am quite worried about fluid intake….” (7)

October 7, 1965: “Georgette remains apathetic—though appetite is good. I am firmly convinced that this animal will never recover….My life is getting to be hell for fear of sudden death or complicating secondary infection—I think we must sacrifice very soon….” (8)

October 28, 1965: “…[W]e set up to sacrifice the animal and do the autopsy. Which was tough on all of us because we’d become so close to these very remarkable animals and would feel their loss.” (9)

Just before her death, Georgette’s final examination was filmed and described as follows:

Attempted to show her poor vision: ability to smell an apple, to root for it, but no fixation of vision—shown by the fact that she appears to want the apple and is searching for it but will not follow it with her eyes. Menace response only occasionally present. Is still able to move all four limbs. Attempts to ‘walk’ or drag her body towards an apple offered by placing it in front of her nose as she leans forward to place her head on the ground….Essentially unchanged from previous day. (10)

Georgette was killed by exsanguination under anesthesia (essentially bleeding to death while unconscious), a method commonly used for animals in research experiments. This procedure is typically done to enhance the quality of tissue and organ specimens following autopsy. The autopsy showed that her brain exhibited abnormalities identical to those seen in kuru victims.

The third chimpanzee—whose name is not known—was also inoculated with kuru and died after Daisy and Georgette.

Several years later, Gibbs and Gajdusek used brain tissue from a man who had died from Creutzfeldt-Jakob disease (CJD) to inoculate a three-year-old male. Thirteen months later that chimpanzee developed symptoms of CJD and was killed 16 months later when his symptoms became severe. An autopsy of his brain confirmed that CJD, too, was transmissible. (11)

Today, scientists believe that kuru, CJD, scrapie, mad cow disease (bovine spongiform encephalopathy), mink encephalopathy, and wasting disease in deer are all transmissible spongiform encephalopathies: versions of a disease with the very odd characteristic of being transmitted by what is currently presumed to be a misshapen protein called a prion. No bacteria, virus, or other organism is responsible for the disease.

The rate of occurrence appears to be amplified in a population when members of a species eat, or are fed, meat from members of the same species. In the late 1950s, and prior to the infection of Daisy and Georgette, the Fore tribe was pressured by the Australian police and missionaries to stop their practice of ritualistic cannibalism. (12) When that happened, incidences of kuru disappeared.

A scientist’s change of heart

Years later when author Richard Rhodes interviewed Clarence J. Gibbs for his 1997 book on the history of spongiform encephalopathies, he reports that Gibbs expressed distress over infecting chimpanzees with deadly diseases: “Joe Gibbs came to hate using chimpanzees for medical experiments. The bright, engaging primates were too human. Gibbs [purportedly] gave up inoculating chimpanzees with lethal diseases years ago—‘I just couldn’t do it anymore,’ he says today.” (13)


Sources

(1) Information for this section on chimpanzees infected with spongiform encephalopathy is taken from: Rhodes, Richard. Deadly Feasts: Tracking the Secrets of a Terrifying New Plague. Simon & Schuster, 1997. 85-98.

(2) CJD Voice, “In Memory of Dr. Gibbs,” February 16, 2001.

(3) Gajdusek DC, Gibbs CJ, Alpers M., 1966 Experimental transmission of a Kuru-like syndrome to chimpanzees. Nature Feb 19;209(25):794-6.

(4) Rhodes, 92.

(5) Ibid.

(6) Ibid., 97.

(7) Ibid.

(8) Ibid.

(9) Ibid.

(10) Ibid., 97-98.

(11) Ibid., 106.

(12) Ibid., 25.

(13) Ibid., 85.

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