Sunday, November 17, 2002
Copyright © Las Vegas Review-Journal

Focus on FALLON: Cancer cluster confounds experts

Frustrated families of leukemia sufferers look everywhere for answers

Photos by Christine H. Wetzel. Floyd Sands, whose daughter died of leukemia last year, says not enough is being done to find out why 16 children with ties to the Fallon area have come down with the disease. He coordinated a door-to-door survey last month in an effort to find out if other cancers show higher-than-expected rates in the Northern Nevada town. In the background, a bus from Sparks High School waits at Laura Mills Park after bringing a class of 32 sophomores to help with the survey. Fallon resident Tommy Thompson answers questions about cancer from his home last month as a camera and sound crew from NBC's "Today" show record the conversation. Fallon's Maine Street, shown here on a night in mid-October, was named after the town founder's home state. Sixteen children who live or once lived in Fallon, a town of 7,500 people, have been diagnosed with leukemia. "I'm very proud of how our community has reacted," says Fallon Mayor Ken Tedford. Former Fallon resident Stephanie Sands, shown here as a senior in her high school yearbook photo, suffered for more than two years with acute lymphocytic leukemia, a rare blood and bone marrow cancer. She died last year at age 21. Students from Northside Elementary School in Fallon walk near a pipeline that transports jet fuel from a plant in Sparks 63 miles to the Naval Air Station Fallon. Some residents suspect jet fuel is responsible for the cluster of leukemia cases, though experts dispute that. An irrigation ditch runs next to one of the many alfalfa fields that surround Fallon. State and national cancer experts are trying to find out why several children with ties to the area have been diagnosed with leukemia. Randall Todd, Nevada state epidemiologist, points to pictures that show technicians taking samples during the investigation of the Fallon leukemia cluster. Todd says he understands criticism from some community members about the seemingly slow progress of the investigation into the cluster. "It's a matter of frustration for the communities seeking answers, and it's also a matter of frustration for the scientists trying to find the answers," Todd says. Click on the image for an enlargement. Graphic by Mike Johnson. Click on the image for an enlargement. Graphic by Mike Johnson. Carinsa Rivers gets a hug from her daughter, Sareynah, 5, who was diagnosed with leukemia in early 2000. She recently underwent her last chemotherapy treatment and has been doing well. A bus drops off children at their school in Fallon. Since 1997, 16 children with ties to the Northern Nevada town of 7,500 have been diagnosed with leukemia. Three have died. Scott Hutner, whose fiancee's child has been diagnosed with leukemia, talks about 5-year-old Sareynah Rivers' recovery. "She's very active," he says. "She's very energetic; she's very bright."

FALLON

The heartbreak shows on his face, in the unguarded moments when his smile suddenly disappears. It shows in his actions, in how he has worked for more than a year to uncover an elusive killer.

And it shows in his words. It comes out sounding like anger.

"I am admittedly obsessed with Fallon and leukemia," he said last month while walking the Northern Nevada city's doorsteps, talking to people one by one in hopes someone will provide the answers he needs. "I don't believe the patients have received a fair shake, and I don't believe the community has received a fair shake."

Last year, Floyd Sands watched his daughter die in a Pennsylvania hospital room. As he held her hand the final day, he kissed her and told her it was OK to stop fighting.

Stephanie Sands had been through so much by then.

She had suffered for more than two years with acute lymphocytic leukemia, a rare blood and bone marrow cancer. A stem cell transplant gave her family hope, but then the cancer spread to her brain and her spinal cord.

She suffered internal bleeding, an infection and septic shock.

She died on Sept. 1, 2001, at the age of 21. Her father has been angry ever since.

Stephanie was one of the first of Fallon's children to come down with leukemia in what health officials say is likely the most staggering cluster of cancer ever investigated in Nevada.

In all, 16 children age 3 to 19 with ties to the town of 7,500 have been diagnosed with different forms of the cancer since 1997. Three have died.

As he's struggled to figure out how Stephanie contracted a disease that each year strikes just 3,000 children nationwide, Sands, 50, has accumulated a collection of hard-earned opinions as well as help from a university professor. He's also honed his instinctive distrust of people in charge.

"I've always hated authority," he said. "I like real people."

Last month, he took a week off work, traveling from the East Coast to Fallon, where he had lived nearly a decade ago. He and a group of community members and others who wanted to help planned to visit every home in town in what Sands acknowledged was an unscientific, rumor-chasing campaign.

It was sort of a return to his activist roots. Sands once was a county-level politician in Pennsylvania, where he earned the nickname "Renegade Republican" for what he characterized as a fight against corruption. He beat an entrenched incumbent by running a feverish door-to-door campaign.

A few years later, he would lose a race, describing it as one of the hardest things he had to endure as a young man. Half a lifetime later, his daughter's illness would put that in perspective.

"It's worse than every parent's worst nightmare. From my standpoint, the worst part was the absolute helplessness," he said.

The cluster surprised even public health experts.

"This is the sort of thing that makes the hair on the back of your neck stand up," said Nevada State Health Division epidemiologist Randall Todd, the man leading the investigation into what scientists call one of the most baffling problems in medicine.

Cancer clusters, or groupings of a specific type of cancer in one area during a specific time period, are notoriously difficult to figure out. Some experts say that, because of public concern and the possible benefits to science, every possible resource should be used to investigate them, despite the fact a cause is rarely found.

Others counter that disease clusters are natural occurrences, like the way balls sometimes clump together on a pool table. They say spending millions of dollars to determine their origin is much like a doctor performing an MRI for a patient's headache, and then forcing the taxpayers to foot the bill when the results come up empty.

Sands is not part of that debate. He simply wants to find out why his daughter is dead. He said he lives each day in fear for the lives of his other children. Both spent time in Fallon, and his youngest, 14-year-old Sierra, was born there.

He has told his story many times, appearing on national news programs such as Phil Donahue's MSNBC show. Last month, NBC's "Today" show followed him around Fallon in preparation for a future broadcast.

Though Sands lined up dozens of volunteers to help, noticeably absent were nearly all of the families of the other leukemia patients.

Though not as vociferous as Sands, some have been critical of scientists conducting the investigation. Others have remained silent, choosing to keep their hurt out of the public eye. Still others have tempered their criticism, at least until final results of the investigation are released.

Even without help from the other families, Sands planned to gather enough volunteers to knock on every door in Fallon. A five-question survey he put together asked residents about family histories of leukemia and other cancers, as well as diseases that may be related to leukemia, such as lymphoma, Hodgkin's disease and aplastic anemia.

With more than 3,000 doors to knock on, he and his volunteers had their work cut out for them.

Typical small town

Fallon is a town founded on the premise that man can overcome nature with persistence and hard work.

Though it averages just 5 inches of rainfall a year, barely more than Las Vegas, Fallon is surrounded by alfalfa fields carved deep with irrigation canals. After almost 100 years, agriculture has become the dominant industry, and the area's residents have been known to brag about their homegrown cantaloupe.

In many ways, Fallon is typical small town America, the kind of place a traveler could pass through in 10 minutes and see little more than fast-food restaurants and convenience stores. It is a place where everyone knows everyone else.

Fallon's mayor, whose home and e-mail addresses are listed in the phone book, does not lock his door when he goes to work at the Goodyear tire shop he owns on Williams Avenue just past Maine Street.

"I'm the mayor of a little town," Ken Tedford said, jingling his "DAD" key chain on his fingers as he sat in his City Hall office last month. "It just happens to be a town I love."

Tedford, a father of four, is the third Tedford to serve as mayor since the city's creation in 1908, following an uncle and a grandfather into local politics. Just down the road from City Hall, Tedford Lane dead-ends at the Wal-Mart.

But Fallon is more than typical, say the people who live there. It's a town where volunteers have erected memorials to the dead children at a local park, and where, despite a recession and national media coverage of the cluster, city officials reported that real estate values remain relatively steady.

Fallon is also where some of the best military pilots in the world learn how to do their jobs better. Naval Air Station Fallon, just outside the city limits, hosts Top Gun, the program made famous by the Tom Cruise movie of the same name. The station has been especially busy in the past year as aircraft carrier-based groups of 1,500 to 2,000 Navy personnel have been constantly rotating in and out to train for war.

Sands worked as a contractor at the base during the late 1980s and early '90s. He suspects the answers to the leukemia cluster lie with the Navy base. He blames military jet fuel, 34 million gallons of which are sent to the base through an underground pipeline each year. The pipeline runs directly through Fallon.

Scientists dispute a link. They point out that, despite extensive testing, jet fuel has never been shown to cause acute lymphocytic leukemia, the type that has been diagnosed in 15 of the 16 Fallon children. Also, they say, there is no evidence that area residents were ever exposed to jet fuel.

Some of the other patients' parents suspect jet fuel might be responsible, but they have their doubts as well.

"He's convinced jet fuel is the cause, but I'm not, and most others aren't either," said Brenda Gross, whose son Dustin was diagnosed with leukemia in 1999. "There's not enough proof either way."

Likewise, Carinsa Rivers, whose daughter, Sareynah, was diagnosed in 2000, said she's waiting for hard evidence.

"I really don't want to put blame on anybody until there's proof," she said.

The parents want an aggressive investigation.

Gross, Rivers and some of the other parents formed an activist group over the summer that they said will investigate the cluster independently of the government.

"What do I expect?" Gross said. "I expect them to research it thoroughly enough that the community and myself knows we're raising our children in a safe environment. I don't think that's too much to ask for."

She added: "And that's to our expectations, not theirs."

The beginning

Long before the words "cancer cluster" became part of the Fallon lexicon, Gross and her husband, Reto, became concerned about their son Dustin.

The youngest of the couple's four children and the only one born in Fallon, Dustin was 3 years old in April 1999 when his parents noticed that he seemed tired all the time, looked pale and was bruising too easily.

His lips took on a translucent hue, and strange red blotches appeared on his skin. His mother took him to the family doctor, who ran a series of tests on the little boy.

He told her Dustin had leukemia.

Specifically, Dustin had acute lymphocytic leukemia of the B cells, or ALL for short. The blood and bone marrow cancer carries an 80 percent survival rate, a far cry from a few decades ago when most of the people it struck died.

By the time Dustin was diagnosed, Sands and his children already had left Fallon. They settled in Mehoopany, Pa.

In July 1999, when Stephanie was 19, she was diagnosed with a slightly different form of leukemia, ALL of the T cells. The prognosis for her form of leukemia is worse than for the B-cell type of ALL. Indeed, Todd said, the three members of the cluster who have died had the T-cell form of the disease.

ALL is the most common cancer found in children, but it is still rare. In the United States, about 3,000 children are diagnosed with leukemia each year. By comparison, about 180,000 women are diagnosed with breast cancer each year.

After Stephanie's diagnosis, her father called an old friend in Fallon to break the news. The friend had heard neither about Dustin's case nor of any other children in town who had been diagnosed. Neither man had reason to believe Stephanie's case had anything to do with Fallon.

"That was it," Sands would say later. "I never gave Fallon a second thought after that."

Sareynah Rivers was next, in March 2000. Like Dustin, she was just 3 years old.

Her mother had just read an essay in which former first lady Barbara Bush told the story of how her second child, Robin, had died of leukemia in 1953.

Rivers, who was then pregnant, said she silently thanked God her daughter was fine.

But soon afterward, Sareynah's skin started to turn pale. Rapidly, she became less active, started bruising easily and suffered unexplained nosebleeds. Her mother called the doctor. Though she had not heard about the other leukemia cases, the disease was on her mind because of the essay.

She told the doctor she suspected leukemia, and tests showed she was right.

Soon, another Fallon child was diagnosed, and then another, and another. By July 2000, five children who still lived in the Fallon area were known to have leukemia.

A local newspaper reporter asked Todd, the state epidemiologist, if so many leukemia cases at the same time in a town the size of Fallon was unusual. It was the first indication Todd had that something was wrong in Churchill County.

He looked at known cancer rates and population figures and estimated that a normal rate of childhood leukemia would mean about 0.2 children per year should get leukemia in the county of 24,000 people. In real terms, that meant one case could be expected there every five years.

Five cases at the same time was obviously too many.

`Inherently unsolvable'

Part of an epidemiologist's job is to figure out how and why diseases spread. Though they are not always medical doctors, they are experts in statistical methods and in public health. Their work typically entails investigating infectious diseases such as meningitis, coordinating anti-bioterrorism efforts, and monitoring outbreaks of sexually transmitted diseases.

By taking on the Fallon cluster, Todd had stepped into a morass.

Somewhere on the order of 85 percent to 90 percent of what are reported as cancer clusters turn out to be either chance groupings of the disease or nothing but normal rates that people finally happen to notice, experts maintain.

For a community to see a particular cancer at two or three times a normal rate would not be all that unusual. In fact, it would be expected in some communities, since others probably have a cancer rate far below normal. It all averages out in the end.

"Clusters are nothing but part of the natural distribution of cancer," said Alan Bender, an epidemiologist and head of the chronic disease and environmental epidemiology section at the Minnesota Department of Health.

Bender, whose department ceased investigations into residential cancer clusters eight years ago, maintains that almost all clusters are dictated by chance. He called them "inherently unsolvable." Not a single residential cancer cluster in the country has ever been solved to the degree that results were publishable in a peer-reviewed scientific journal, he said.

Clustering of leukemia cases is like a game of keno, Bender said.

"After the game is played, there is always a spot on the board where the numbers cluster," he said. "You just can't predict where that's going to be."

But when a cancer cluster is found, particularly with children involved, the emotional toll is much higher and the public is bound to cry out for an extensive investigation, he said.

Few besides Bender take such a radical stance, at least publicly. Even those experts who believe public hysteria drives policy more often than good science

point out that doctors have been conducting cancer cluster investigations for hundreds of years and have, a handful of times, been successful in identifying a cause and putting a stop to it.

Todd knew all of that going in. Regardless of past failures, he believed he should investigate the Fallon cluster.

"Just based on the statistics, this looked significant to us and warranted further investigation. We felt the community expected that from us, especially the case families."

The first step in any disease investigation is to find out what the patients have in common and then what the differences are between them and the area's healthy population.

Todd knew that the city of Fallon's municipal water supply was notoriously high in arsenic, a naturally occurring heavy metal that has been linked to bladder and skin cancers, as well as liver problems, but never to leukemia.

A quick look at a map showed Fallon's victims were spread throughout Churchill County, not just in the city limits. Some drank well water, some city water, and some bottled water.

Besides, the arsenic had been in Fallon's water for decades. If it were the culprit, wouldn't there be a prolonged history of leukemia in the community?

Because of the long-standing arsenic problem, Mayor Tedford said, Fallon has some of the most scrutinized water in the country. It has been tested and retested extensively. He does not believe it is dangerous.

"I can tell you what's in the city water is not giving you cancer," he said.

Todd and Dr. Mary Guinan, then the state's health officer, prepared a 32-page list of questions they would ask families.

In addition to asking about drinking water, Todd's questionnaire asked the patients' families what kind of cleaning products and other chemicals were in the home, where they had lived as far back as two years before the affected child was conceived, jobs held by the parents, family medical histories, alcohol consumption during pregnancy, breast-feeding habits, if prenatal ultrasound testing was performed, military history, and where the children attended school, among other topics.

When the surveys were complete -- it took about three hours for each family interview -- Todd fed the data into a computer and looked for similarities. There was only one, and it was already known: All of the families lived in Churchill County.

Soon, more leukemia cases were diagnosed, some in children who no longer lived in Fallon. Todd had to question their families, too.

Stephanie Sands' case finally came to the attention of Nevada officials after her father, surfing the Internet late one night, happened upon a story about the cluster on a Reno television station's Web site.

He immediately called Fallon's hospital, and his story hit the media soon after.

A case was discovered in a little boy who no longer lived in Fallon. He was diagnosed in 1997, and his case is now considered the first of the 16.

"Unlike a lot of other clusters, we were investigating this one while it was unfolding," Todd said. "We would think we'd be done (questioning families), and then we'd get another case."

As the investigation continued, the politicians got involved.

In the span of two months in early 2001, the city of Fallon hired a public relations firm to deal with the flurry of media inquiries, U.S. Sens Harry Reid, D-Nev., and Hillary Clinton, D-N.Y., held public hearings in town, and the Nevada Assembly Committee on Natural Resources, Agriculture and Mining heard three days of testimony from community members and experts.

Reid demanded federal involvement in the investigation.

As it turned out, Guinan, the state health officer, had spent most of her public health career with the Centers for Disease Control and Prevention and had numerous contacts in the agency. They were called in to help.

"We've always worked with local health departments at their request on dealing with clusters of health events," said Thomas Sinks, the associate director for science at the CDC's National Center for Environmental Health.

For 20 years between the 1960s and 1980s, CDC researchers who believed some cancers might be infectious investigated 108 cancer clusters in 29 states and five foreign countries. Most involved leukemia.

Not once did they find a clear cause, and they moved on to other research, Sinks said.

But Sinks, part of the team investigating the Fallon cluster, said technology that did not exist 20 years ago might help uncover causes for leukemia.

The technology, called biomonitoring, can measure chemicals in blood or urine down to parts per trillion. Experts liken that kind of precision to detecting a single grain of sand buried in the carpet of a 3,000-square-foot house.

Examining possibilities

In 1963, in the Sand Mountain range about 30 miles east of Fallon, a 13-kiloton nuclear bomb was tested underground. But, officials say, the radiation from what was called Project Shoal has not traveled anywhere close to Fallon.

The groundwater in the area flows away from town and is in a different aquifer than those used by the city and by private wells.

Because of the large agricultural community, pesticides also have been a concern. But so far, there has been no evidence of pesticide contamination in the water or the homes of the affected families.

What if the cause was not a hidden environmental pollutant at all, but instead some sort of infectious agent such as a virus or a combination of viruses?

"Every expert that I've spoken to seems to feel that this is going to turn out to have something to do with viruses, or certain viral infections in people with a specific genetic susceptibility," said Dr. Tim Hockenberry, who lives in town and has treated several of the leukemia patients.

A panel of cancer cluster experts that the state Health Division had formed as the cluster investigation got going came to a similar conclusion. In a report released in early 2001, the panel concluded that of the three possible causes -- simple chance, chemical pollution, or some sort of combination of infections -- chance and chemicals were unlikely.

"The panel members were skeptical that a chemical exposure could explain the excess cases of ALL in Fallon," the panel's report reads in part. And, although the panel did not discount the possibility that the cluster was a random occurrence, members doubted that was the case. The sheer numbers over such a short time period in such a small population dictated otherwise.

The infectious agent theory, if true, would require an astounding combination of bad luck, bad timing and bad genes, experts concede.

Called population mixing, the theory emerged after researchers in Europe found that leukemia clusters often occurred in isolated rural communities that saw sudden influxes of new people, not unlike a flurry of Navy personnel coming into Fallon.

The theory postulates that, because of an area's history of isolation, new people can bring viruses or other infections into town that were previously absent from the community. The result is that people with immune systems unfamiliar with the infections, if they're genetically susceptible, might get infected.

"The hypothesis suggests that ALL is not infectious, spreading from one person to another, but an unusual complication to a common infection within a susceptible population," according to the report.

Experts put it like this: Smoking cigarettes is a known cause of lung cancer, but that does not mean that every person who smokes will get cancer. A person's fate hinges in part on genetics, other behaviors, and on how much the person smoked.

"There's almost no disease process where, if you are 100 percent exposed, you stand a 100 percent chance of getting it," Todd explained.

But, instead of such a complicated mix, the cause might be a single, but elusive, virus, some doctors say.

Viruses are known to cause other cancers. The sexually transmitted human papilloma virus, or HPV, can cause cervical cancer, for example. And scientists know that viruses cause leukemia in cows and cats, called the bovine and feline leukemia viruses. The problem is, no one has ever been able to find a similar virus that causes the most common types of leukemia in humans.

"It's a question that's open to a lot of debate," said the CDC's Sinks.

A puzzling discovery

As the investigation progressed, state and federal field workers went to Fallon and collected blood, urine and cheek cell samples from family members of leukemia patients.

They also collected dust, water and other samples for extensive testing.

In a first round of reports released in August -- more are expected in February -- doctors announced a puzzling finding: In addition to arsenic, high levels of the heavy metal tungsten were found in the urine of not just the case families, but in that of 80 percent of the 205 people tested in Fallon, including people with no connection to the leukemia patients.

The discovery of tungsten, a naturally occurring metal that has never been shown to cause leukemia, baffled investigators.

"We really can't interpret what the levels mean," Dr. Carol Rubin, chief of the CDC's health studies branch, told community members at a town hall meeting.

"It's another piece of the puzzle," Todd echoed. "It's like when you work a jigsaw puzzle and you get a piece that's kind of unusual and you wonder, 'Where does this fit?' We don't know where it fits yet, but it sure is an interesting piece."

Sinks said the CDC hopes to study tungsten's effects on human health more extensively.

With the tungsten discovery, another unusual connection was made: A small town in southern Arizona also had seen a sharp rise in childhood leukemia cases. And, as in Fallon, the U.S. military had an air base nearby.

Sierra Vista, with a population of about 40,000, has seen nine cases of leukemia since 1995. By coincidence, one child who grew up in Sierra Vista was diagnosed with leukemia shortly after she left there and settled in Fallon. She is counted among Fallon's 16 cases.

Sierra Vista is also home to the U.S. Army's Fort Huachuca and Libby Army Airfield, which use about 2 million gallons of jet fuel a year, compared to Fallon's 34 million gallons.

Mark Witten, a research professor at the University of Arizona College of Medicine's Department of Pediatrics, conducted a study to determine whether the two towns had anything else in common.

Working with a tree-ring expert, he took samples from several trees in both towns. He later discovered evidence in the rings that showed tungsten appeared to be high in both areas. He recently collected more samples to study.

Soon after Witten's discovery, the city of Fallon announced that tests conducted on the municipal water supply found that tungsten levels were high in the city water.

The findings explained how the tungsten got into the people, but it didn't do much for investigators' questions about its possible health effects.

Witten, who is best known as an expert on JP8, the military jet fuel, said he is studying tungsten further to see what effect it has on leukemia cells. He'll do the same experiment with jet fuel, he said.

In previous experiments, Witten has said, he linked high doses of jet fuel to cancer in mice, though never in humans.

One problem with the jet fuel theory is that there is no known way for the fuel to have poisoned the bodies of the leukemia patients.

The water in Fallon is free of jet fuel contaminants, health officials said, and the pipeline that carries the fuel 63 miles from Sparks to Fallon has never been shown to leak.

Some residents in town say the Navy planes that fly overhead have routinely dumped their fuel as they prepare to land.

"There's a common public misperception that fuel is dumped from aircraft all the time," said Zip Upham, a spokesman for the Naval Air Station Fallon.

He said that when civilians see military aircraft appearing to dump a liquid, it is almost always water vapors created by the plane's high speeds.

"None of that's fuel," he said. "We're just, in effect, squeezing the water out of the air."

Sands, who said Witten was instrumental in helping him design his own survey, called the discrediting of jet fuel as a possible cause "a dog and pony show."

He pointed in particular to a town hall meeting in which the Agency for Toxic Substances and Disease Registry, a sister agency of the CDC, announced in unequivocal terms that the pipeline "does not pose a current or future public health hazard."

"Their declarations, the terms were absolute," Sands said. "I learned a long time ago, when somebody speaks in absolutes, there's probably a whole lot of lying going on."

Community expectations

Sands and the volunteers got to almost all of the 3,000 houses in Fallon. They had planned on three days; it took them nearly two weeks. He expects to release the results at the end of this month. Sands said he wished he had more time, so he could cover the rest of the county. But he was happy with the effort, especially the help he got from the community.

A newspaper reporter from Reno even helped when he made an announcement about Sands' survey in a journalism class he teaches at the University of Nevada, Reno. About a half-dozen of his students showed up to assist.

The reporter himself used a Tuesday afternoon to help Sands coordinate survey efforts as a busload of sophomores from Sparks High School showed up to knock on doors.

Sands said he was inspired by the assistance. It's one of the reasons he would love to move back to Fallon, someday.

"Aside from the obvious, I have no regrets about moving to Fallon," he said. "As soon as the cause is found and abated, I'm moving back here. But now, I can't have my kids living in Fallon."

Sands said the fact that the experts say they have never found a clear cause in another residential cancer cluster does not faze him. Instead, it spurs him on.

"They can do their thing," he said. "But that approach, by the CDC's own admission, has failed 108 consecutive times. ... Even a blind squirrel will find a nut occasionally. I'll take another course."

Todd said he understands the frustration that Sands and some of the other families feel. The investigation sometimes can seem to outsiders to be moving slowly, he acknowledged, but that is not the case.

"I have been in this bureaucracy for more than 20 years, and I have never seen it move this fast," he said. "Laboratory work is slow work. You have to be careful how much you rush it, because you want the results to be accurate."

He said estimates on how much money has been spent on the investigation haven't been completed, but he guessed it was "easily in the hundreds of thousands. Probably over a million."

He said people generally don't understand why science seems unable to solve such a puzzle. After all, so much progress has been made in the treatment of the disease -- as evidenced by the almost complete recoveries of both Sareynah Rivers and Dustin Gross, as well as several other patients -- that people have come to expect similar progress in finding its cause.

"That's a huge problem for people," he said. "How can we do one without doing the other?"

But, he and most others concede, no matter how much time and money are spent on trying to find its cause, the Fallon cluster will probably remain unsolved.

"I've been accused of having a defeatist attitude, but I'm only trying to be realistic," Todd said. "I have told the people in Fallon repeatedly, the odds of us finding a reason for this cluster are minimal. I'd be lying if I said anything else."

Some members of the community, he said, expect the experts to tell them why anyone who lives there gets sick, whether it be leukemia, a rare brain cancer or another of the 100 different kinds of cancer, an immune system disorder, or even something common such as diabetes.

That, he said, would be impossible.

"I know of no one who can answer that question," Todd said. "Except maybe God."