Scientist Studies Creatures That Bug Us

March 20, 1994|By Mike Klingaman | Mike Klingaman,Sun Staff Writer

Come spring, folks drive through the Maryland countryside in search of pastoral scenes.

Not J. Ralph Lichtenfels. He's concerned about what's creeping up the clover.

It's what he cannot see that fascinates this scientist. He passes children on a playground and imagines what's lurking beneath the sand. He sees people splashing in a pool and wonders what's swimming beside them in the water.

What he's pondering is an unseen army of parasites. Tapeworms, ticks and mites. Roundworms, flukes and flies. Creatures as large as a giant noodle, or as small as a virus.

Creatures that invite themselves to dinner and then sample the host.

Most Marylanders think of parasites as hideous but insignificant pests; a plague on the Third World, perhaps, but not a potent environmental force in this neck of the woods.

Wrong, says Dr. Lichtenfels, a scientist with the U.S. Department of Agriculture in Beltsville and one of the world's leading parasite sleuths.

The beasties in his collection can't be taken lightly. They affect our health, the Chesapeake Bay, livestock, food and drinking water. And if you study them long enough, they seem remarkable in many respects.

Single-celled parasites, such as MSX and Dermo, have devastated the oyster population in the bay; ribbon-shaped worms many feet long race through thoroughbred horses, cattle fTC and sheep; confetti-like nematodes contaminate fish in local waters; and tiny protozoa can slip undetected into municipal water supplies and bring whole cities to their knees.

Parasites are so numerous that Dr. Lichtenfels offers this grotesque scenario: "If, magically, every part of the world were to disappear except for parasites, you could still see the outline of the earth. They are in the ocean and the soil. They are in beer-soaked coasters in English pubs, and in hot springs in Alaska.

"They parasitize every living species."

And spring is their wake-up call.

What's creeping up the clover? The newly hatched larvae of hungry worms hoping to land in the bellies of untreated livestock, where a buffet awaits. What's lurking in the sandbox? The thick, sticky eggs of the ascarid, a parasite found in cat feces. If ingested and allowed to flourish, the worm can cause blindness or death.

What's floating in the swimming pool? It could be nagleria, a nasty one-celled creature that can pack a lethal punch in waters that are inadequately chlorinated.

Among parasites, size is no tip-off to strength.

The parasite cryptosporidium, found in animal waste, contaminated Milwaukee's water last spring and caused an estimated 370,000 cases of intestinal illness. Forty-seven people died; most already had compromised immune systems.

Concern that the same microorganism might have infected Washington-area water supplies -- it hadn't -- caused a flurry of temporary restrictions in December.

Parasites thrive in obscurity, something they don't get from Dr. Lichtenfels, curator of an unusual museum at the Beltsville Agricultural Research Center.

Here, in the basement of a drab yellow concrete block building, resides the U.S. National Parasite Collection, a rogue's gallery of nematodes and protozoa that have long plagued man and beast.

Here, trapped in formaldehyde-filled bottles, vials and Mason jars, float nearly every worm, tick and mite known to man. One-hundred-thousand strong. Dead, of course. The Parasite Hall of Shame.

Used mainly by scientists, the museum is not part of the regular Washington sightseeing tour. Nor is there a gift shop on the premises; just a large, climate-controlled room filled with shelf upon shelf of bizarre specimens, some more than 100 years old. Many resemble leftover pasta.

This is the domain of Dr. Lichtenfels, 55, the zoologist who has rubbed elbows with these macaroni-shaped creatures for more than two decades. The collection, the second-largest accumulation of parasites in the world, had its centennial two years ago.

The largest specimen is a 3-foot kidney worm, pencil-thick, removed from a dog; the smallest is the minuscule larva of a pinworm, a common domestic parasite.

Here also are the barnyard's worst nightmares: nematodes that attack pigs, cows and chickens from the inside out.

Dr. Lichtenfels understands the public's "yuk" reaction.

"Most people think parasites are unsavory things. Anything that lives on another organism would give you that impression," he says. "But they are really very elegant animals; they look beautiful under the microscope.

"Like insects, they are eminently successful at exploiting the environment. We're dealing with the bad guys, but that doesn't mean they can't be useful."

For instance, parasites are being touted as good indicators of environmental quality, Dr. Lichtenfels says.

"Parasites have such complex life cycles," he says. "People have begun using them to assess quality of life. If parasites disappear, it's a tip-off to a sick environment."

Weep not for parasites. The museum adds about 1,000 specimens each year, several hundred of which are newly discovered species.

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