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Brain Parasites, California's Hidden Health Problem

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Sara Alvarez was afraid.

The doctors told her she needed surgery — brain surgery. Operations on such a complex organ are never simple, but this procedure was exceptionally difficult. There was a high risk of complications, of debilitation, of post-op problems. Alvarez might wake up paralyzed. She might wake up legally blind. Worse still, there was a chance she might not wake up at all.

Her mad dash to the emergency room had all begun with a walk in the park four days earlier. It was December 20, 2010, in Sunnyvale, Calif., a town that lives up to its name. The West Coast winter, not as long or as harsh as seasons in the East, gave her the opportunity to take her youngest child out for an afternoon stroll.

In the fading light of dusk, Alvarez, too, began to fade. She lost the feeling in her right leg. Her right foot followed suit. She couldn’t lift or move her right hand. She was weak, and her body was numb.

There was fear then, too.

At 10:15 p.m., Alvarez says her husband drove her to Redwood City. That night she became a patient at Kaiser Permanente Redwood City Hospital. She says the doctors batted diagnoses back and forth. It was a tumor. No, it was cancer.

It was Christmas, and Alvarez’s children cried and prayed, terrified that an unknown affliction would steal their mother away. Finally a CT scan revealed the malady. Alvarez had neurocysticercosis — a calcified tapeworm lodged in her brain.

Neurocysticercosis, which is common around the world but is not recognized as a major health concern in the U.S., has taken root in California, some health officials say. The disease is easy to prevent and relatively inexpensive to treat if caught early on. But once in the advanced stages, these brain parasites are costly to both patient and government.

The problem is that, due to a lack of education, most of the population doesn’t know that there’s a parasite wriggling within them, says Patricia Wilkins, a scientist with the Center for Disease Control and Prevention (CDC). Latinos, the community most afflicted by the disease, do not receive outreach or education about how to avoid or treat the potentially life-threatening organism, Wilkins adds.

Neurocysticercosis “primarily exists in marginalized populations, Hispanic immigrants,” Wilkins adds.

The National Institutes of Health classifies neurocysticercosis as the leading cause of epilepsy worldwide, and the World Health Organization (WHO) estimates that tapeworms infect 50 million people globally. The CDC says an estimated 1,900 people are diagnosed with neurocysticercosis within the United States yearly.

According to a January 2012 study in PLOS Neglected Tropical Diseases, California bears much of the burden with 304 hospitalized cases in 2009, the most recent year for which statistics exist. Eighty-five percent of patients in California were identified as Latino, and 72 percent were reported in the southern half of the state.

The high percentage of Latino cases is not surprising. Neurocysticercosis is common within third-world countries in Asia, Africa and Latin America. The disease's telltale symptoms of paralysis, extreme headaches and chronic seizures present themselves in mass form. Individuals contract neurocysticercosis after becoming infected by tapeworm carriers. Immigrants traveling between countries, such as migrant workers, are often unwitting tapeworm hosts, transporting the disease across borders in their guts.

Scientists aren’t quite sure how it works, but tapeworm larvae seem to have developed a chemical secretion that keeps the human body’s immune system from barging in on their banquet. People can live for decades without any symptoms of neurocysticercosis because the tapeworm larvae break down natural defenses. Unfortunately, tapeworm larvae can’t live forever.

“While it’s alive, it’s a problem, but when it starts to die it’s a bigger problem,” Despommier says.

When the larvae die, the chemical balance is restored, and the immune system begins to attack, causing headaches, seizures and paralysis. Alvarez says she experienced debilitating headaches for 20 years before her diagnosis, but she probably consumed tapeworm eggs much earlier than that. When Alvarez immigrated to the United States in

the late 1980s she complained to American doctors of a pain so absolute it blinded her and made her vomit.

They gave her Tylenol.

“That’s a very typical story,” says Darvin Scott Smith, chief of infectious disease at the Kaiser Hospital.

Many physicians, even those in highly populated areas sizable immigrant populations, are unaware of the disease and how to diagnose it, he adds. Even many of the health organizations that target Latinos had never heard of neurocysticercosis and said their institutions were not funding research or community outreach.

Nobody cares about this disease, and they should, if not from a humanitarian point of view than from a fiscal aspect, says Wilkins, a scientist with the CDC.

Drugs such as Ablendazole and certain steroids, which are used to treat tapeworms and brain swelling, are relatively inexpensive — a maximum of a few hundred dollars. Wait until it’s a serious problem, though, and the dollar amount rises dramatically.

The CDC reports the average cost of neurocysticercosis at $37,600 per hospitalization.

The most common form of payment is Medicaid, a tax-funded public service. In Los Angeles County, the economic impact is even more pronounced, costing $66,000 on average, the increase likely due to the high cost of health care in the state, says Frank Sorvillo, a University of Los Angeles professor of epidemiology.

Despite a marked decrease in immigration over the past few years, the number of neurocysticercosis cases has remained relatively constant since 2001, when there were 386 recorded hospitalizations in California. This suggests that the parasite has taken hold in the U.S., Sorvillo says.

These numbers are likely underestimated. Only five states — New York, California, Texas, Oregon and Illinois — report the disease, and the data is inconsistent. Oftentimes, departments rely on each other to deal with paperwork, and the numbers are never recorded, Smith says. As a result, not much is known about tapeworm outbreaks in the U.S. — or the parasites themselves. Scientists still consider much of their life cycle a mystery.

Pork tapeworms, or Taenia solium, are complex organisms. They exist in three life stages: egg, larvae and adult, but their growth is not a straight progression from one form to the next. Tapeworm larvae enter the body when humans eat contaminated pork.

The babies, about the size of peas, fight their way into the small intestine and attach, using rows of grappling hook-like teeth to make tiny slices into the soft flesh of the intestinal walls. The parasites cling to the slippery surfaces of their new homes and begin draining nutrients from their host. If all goes well, adults can grow up to 20 feet long.

It sounds unpleasant, but if you’re going to contract a tapeworm, dealing with 20 feet of invertebrate is really the way to go. Researchers say that adult Taenia solium is relatively harmless and asymptomatic. The real trouble starts when they begin to reproduce within their human host.

Tapeworm adults are made up of hundreds of segments called proglottids. The parasite grows like a fingernail, the newest addition at the head and old material at the tip. The senior proglottids contain eggs — thousands of them. During the course of a natural lifecycle, the proglottids are discarded through their host’s anus. A family member, friend or restaurant cook infected with an adult tapeworm can secrete tens of thousands of tapeworm eggs daily, which can be easily ingested by others.

Being infected with the eggs, however, doesn’t result in an adult tapeworm. The eggs just develop into larvae—and grow no further. According to parasitologist Judy Sakanari at the University of California, San Francisco, no one really knows why. Unlike most animals whose lifecycle follows a child-adolescent-adult pattern, these eggs will never mature into adulthood. Their development is stunted at the larvae stage, which allows them to ride the bloodstream. They use their hooks to rip apart tissue and gain access to nutrient-rich hotspots. Some of these miniature reapers ultimately find their way into the brain. That’s where the trouble starts — and stops.

While alive, the larvae are not as dangerous as they are when they’re dead. The brain calcifies the dead larvae, and, oftentimes, surgery is necessary to remove them. This ramps up costs for the hospital and drains Medicaid funds. The State of California is not responding to the issue, Wilkins says, because there isn’t enough funding to tackle every bug that infiltrates a community. Health officials must pick and choose which diseases require the most resources. So far, neurocysticercosis has not been one of them.

In a 2000 proposal filed by the WHO, doctors called for international monitoring of neurocysticercosis. They argued that surveillance was key to eradication, that statistics were paramount if governments across the globe had any hope of reducing epilepsy and increasing quality of life. So far, the petition has not experienced much success.

In early January 2011, Dr. Smith of Redwood City, Calif. celebrated his birthday in the operating room of Kaiser Hospital, observing Sara Alvarez’s brain surgery. Medical professionals trimmed Sara’s hair, gingerly peeled away layers of skin and cut through a portion of her skull. Hours later, the chief of infectious disease watched as a neurosurgeon plucked a calcified tapeworm larvae from Sara’s head.

Before she was diagnosed, Alvarez had never heard of neurocysticercosis, and she still isn’t sure who gave her the eggs. It could have been a chance encounter, or one of her loved ones might be a carrier. She’ll never know for sure. The host may remain undetected and contagious, spreading the disease — thousands of eggs at a time.

Story and images by permission of Sara Alvarez and Dr. Darvin Scott Smith

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The views expressed are those of the author and are not necessarily those of Scientific American.

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