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.
