Seeking parasitic relationships Parasites: Scientist probes the insides of birds and animals to study the unwelcome creatures that live there.

February 25, 1997|By Dennis O'Brien | Dennis O'Brien,SUN STAFF

Eric Hoberg knows a lot about parasitic relationships.

Not people. Organisms.

He is one of about two dozen scientists in the world drawn to the stomachs of sea birds, the intestines of sheep and the lungs of deer -- in short, to the haunts of creatures that live inside other creatures.

The 43-year-old parasitologist has gone literally around the world in pursuit of lungworms, tapeworms, flukes and other dependent critters, returning, usually with his "souvenirs," to his cramped office in a chilly basement storage room of the federal Beltsville Agricultural Research Center.

One floor above, the National Parasite Collection has grown to 100,000 samples, the largest such collection in North America.

The collection has ranks of jars filled with wormy creatures afloat in formaldehyde and labeled "stomach of swine" and "skin of dog." From the jars, Hoberg recently plucked tapeworms he extracted from Siberian sea birds six years ago and a lungworm he discovered in a Canadian musk ox.

These parasites are exquisite, Hoberg says -- which may not be the descriptive term the rest of us might choose.

But in them, Hoberg sees awesome power. While parasites give some birds colorful plumage, for example, they also can cause diseases such as malaria, or cripple calves at birth and wipe out populations of moose.

Hoberg has been hooked on parasites for 22 years, since he traveled to the Aleutian Islands as a student at the University of Alaska to examine sea birds.

Understanding his exquisite creatures is vital to industries and to cultures dependent on animals, Hoberg says.

"If we want to introduce any species, a new deer, or a goat into this country, and that species has a parasite that's a danger to other species, we need to know that," Hoberg says.

Domestic breeders of ostriches and llamas, for example, must know what parasites they carry before they can be sold as pets.

Sometimes the need to know is more urgent, and Hoberg has played the role of parasite detective.

In 1994, he was dispatched to Canada to figure out why musk ox in the Northwest Territories were dying in droves.

About 10 years earlier, the musk ox had been brought into Canada from Greenland as a food source for the tribes there. But wildlife biologists became alarmed when the herd of 1,800 shrank to about 900 in six years.

Hoberg and University of Saskatchewan researchers went to the Arctic, where they shot a musk ox, put it on ice and rushed it 70 miles to the nearest laboratory.

An autopsy solved their puzzle. At home in the beast's lung, they found a slithery 18-inch lungworm.

The lungworm, a new species, is in the collection now -- impressively identified as "Umingmakstrongylus pallikuukensi," a Latinized mouthful taken from the Inuit word for musk ox.

Hoberg hopes that continued study of the parasite will develop a toxin that will kill a lungworm without hurting the musk ox it lives in.

There's plenty more work to do, Hoberg says. Scientists have been studying parasites since the 1850s, but so far, only a third of the estimated 3 million parasites in the world are discovered.

Take sharks, for instance. Parasitologists have examined only 20 percent to 30 percent of the 800 known species of sharks.

But every time they get to a new kind of shark, five or six new species of tapeworms are discovered.

"The problem with parasites is that there are so many of them, and so many of them that have yet to be described," Hoberg said.

Consider Beltsville's collection as one in progress.

Pub Date: 2/25/97

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