Palaces For The People
Saturday, January 03, 2004
Mad Cow Variant That Hits Humans Is a Puzzle (washingtonpost.com)
By Rob Stein
Washington Post Staff Writer
Saturday, January 3, 2004; Page A01
She had just graduated from college when the frightening symptoms started to surface. The vivacious, easygoing 22-year-old suddenly became inexplicably irritable and short-tempered. Then her memory started failing. Her right hand began to tremble. Her leg started to shake, and her balance gave way.
"She just cried and cried and cried," said the Miami woman's father, who asked that his daughter be identified only by her first name, Charlene. "She knew she was sick, but she didn't know what it was."
Within six months, Charlene was incoherent and helpless, unable to speak or control her bodily functions. Today, two years after the first symptoms appeared, she lies bedridden, her brain ravaged. She is fed through a tube in her stomach and has no hope of surviving.
"She went down very quickly. She lost awareness. She doesn't know where she is and who anyone is," said her father, Patrick. "Every day is hard."
Charlene is the only person in the United States confirmed to have the human form of mad cow disease, in which a misshapen infectious protein inexorably erodes the brain. She is believed to have contracted the insidious disease by eating infected beef during her first 13 years of life, when her family was living in Britain.
Charlene's story is the kind of tragedy that the United States is desperately trying to avoid after the discovery of the first U.S. cow carrying the infection.
"I'm terrified that this is going to happen again. It's like being in the U.K. again, watching this all over again," Patrick said. "I'm worried that people may be eating beef that is contaminated and that down the road people are going to start to die from this disease."
Government officials and many independent experts stress that even with the long-feared detection of an infected cow in this country, existing safeguards mean the risk that anyone eating U.S. beef will face Charlene's fate remains extremely remote. Agriculture officials announced drastic new measures this week in the hopes of erasing any possibility of danger.
But as experts debate the effectiveness of the new protections, try to figure out how the Holstein became infected and search for other contaminated cows that may be in the food supply, the discovery of the infected animal has focused attention on the many uncertainties about the illness and on how well the government monitors for homegrown cases.
"I think the occurrence of mad cow disease is something of a wake-up call that no matter how we insulate ourselves, we need to be increasingly vigilant and fill in whatever gaps there might be," said Raymond Roos of the University of Chicago, who studies the disease.
Worldwide, 153 cases of the human form of mad cow disease have been reported. The overwhelming majority -- 143 -- occurred in England, where the disease was first detected in 1996. Six cases have been documented in France, and one each has been reported in Italy, Ireland, Canada and the United States. All have been linked to the mad cow epidemic in England in the 1980s.
In cows, the disease is officially known as bovine spongiform encephalopathy (BSE) -- "spongiform" because the disease makes the brain look like a hole-riddled sponge. In humans, the disease is called variant Creutzfeldt-Jakob disease (vCJD). It is named after Creutzfeldt-Jakob disease (CJD), a similar but distinct brain malady first identified in Germany in 1920.
CJD is one of a few diseases caused by prions. Prions are strange, normally harmless proteins found in the brain that contort into a shape that makes them lethal to nerve cells. In CJD, which occurs in about 1 out of every 1 million people, the malformation occurs spontaneously for reasons that remain a mystery. Victims quickly and progressively lose their ability to think and control their bodies. It is untreatable and invariably fatal.
The disease almost always hits people in their fifties, sixties and seventies. In the late 1990s, however, British doctors noticed that unusual cases appeared to be striking people in their twenties and thirties. Scientists traced the baffling cases to meat from cows stricken by mad cow disease -- which is also caused by prions.
Until then, the only known cases of transmitted CJD involved transplant patients who were given nervous system tissue or short children who received injections of growth hormone derived unknowingly from infected people. It is also passed down through generations in rare families.
In 1996, Britain faced the possibility of a devastating epidemic of the first prion disease known to be spread by eating infected animals. U.S. officials began monitoring the incidence of CJD in this country and started investigating unusual cases.
"Because of travel to the United Kingdom, some Americans may have been exposed to BSE," said Ermias Belay, a medical epidemiologist at the federal Centers for Disease Control and Prevention in Atlanta. "It's an awful disease."
The key was to differentiate between CJD, the spontaneous form of the disease, and vCJD, the human form of mad cow disease. Although the two diseases are similar, they differ in ways aside from the age of typical victims.
The first symptoms of CJD are usually memory lapses and difficulty standing, walking and talking. Victims deteriorate rapidly, becoming bedridden in weeks or months and falling into a coma before they die, usually within a year.
In contrast, vCJD patients tend first to develop psychiatric symptoms such as Charlene's -- depression, anxiety, withdrawal. They also often have severe pain or tingling and burning sensations in the legs before they begin to lose the ability to stand, walk and talk. As in Charlene's case, the agony often stretches over two to four years before death.
Magnetic resonance imaging (MRI) can frequently detect unique changes in the brain that distinguish vCJD from CJD. Sometimes the prions can be found in the tonsils of vCJD victims, as was the case with Charlene. An electroencephalogram (EEG) can sometimes spot a distinctive brain wave pattern in CJD patients that does not occur in vCJD patients.
But the only way to make a definitive diagnosis is to do a detailed examination of the brain after death. The brains of vCJD patients have telltale deposits of plaque. There are also subtle differences in the prion proteins that can be detected by chemical analysis.
In the past six years, doctors have shipped samples from the brains of 732 patients who have died from suspicious diseases to the National Prion Disease Pathology Surveillance Center, which the CDC established at Case Western Reserve University in Cleveland. Scientists conduct a battery of tests for signs of vCJD and another disease caused by prions that affects elk and deer, called chronic wasting disease. It has not been found in humans.
Some skeptics say odd cases or clusters of cases of CJD have occurred in the United States that may be homegrown vCJD, but the CDC and other experts maintain that none has been confirmed.
"We think we are in the best position to discover if there is an atypical case," said Pierluigi Gambetti, who directs the Cleveland center. "We have not seen one case of variant CJD that was a real American indigenous case."
But Gambetti acknowledged that he gets samples from only perhaps half of the cases of CJD that would be expected to occur each year in the United States.
"It's not complete surveillance. It's like you go to the airport, and half the people go unchecked. You would not be happy to fly in an airplane where half the people have not been checked at all," Gambetti said. "If we want to protect Americans, we need to examine many more cases."
Nevertheless, experts doubt that large numbers of cases are escaping detection in this country. The main reason is the relatively small number of cases that have occurred in Britain even though more than 1 million infected cows may have entered the food supply there.