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USF professor is expert on tracking human infections to their animal sources

ST. PETERSBURG — Who's to blame for the swine flu crisis that is scaring the whole world? May as well start with Noah. It goes that far back.

The ancient agricultural partnerships of man and animal combined with modern industrial abuses are the root causes of nearly all of today's infectious scourges. Recognition of that fact has led to an emerging research field called conservation medicine. It combines veterinary, human and environmental sciences — disciplines that previously have not occupied the same university lab spaces.

It now covers a range of animal and environmental issues important to Florida — including diseases afflicting manatees and the susceptibility of Florida birds to the West Nile virus. The University of Florida even has researched links between malaria and fish farms in deforested parts of Peru.

One of its foremost interpreters is veterinarian Mark Walters, an associate professor at the University of South Florida St. Petersburg. He has spent his career trailing the most horrible human infectious diseases to their animal roots. He is the author of Six Modern Plagues and How We Are Causing Them. Influenza could just as well be Plague No. 7.

Walters' search has taken him to a barn in West Sussex, England, where the first case of mad cow disease was discovered in 1984. It also has taken him to the open-air bushmeat markets of Gabon, Africa, the kinds of natural stew pots for a deadly monkey-to-human virus like HIV.

He brings to the field a peculiar blend of skills. He was an English major in Montreal; he earned a master's in journalism at Columbia University in New York, and a D.V.M. from Tufts University School of Veterinary Medicine in Massachusetts. He's 57. He and his wife, Noelle, have two children.

Walters offers a simple scenario for how the current swine flu crisis may have started. It begins in a primitive setting — a pond beside a pig farm deep in rural Mexico. The suspected ground zero is a pig farm close to a little mountain village called La Gloria, near Mexico City.

A weary migratory bird spots the pond and lights on its surface. It mingles with domesticated ducks that belong to the pig farmer. It transmits viruses to those ducks.

Pigs wallow near the pond. Eventually, the virus jumps from the ducks to a pig.

Unbeknownst to most people, pigs are flu mixing bowls. They commonly accommodate three kinds of flu viruses — bird, human and swine — often all three at the same time.

Imagine the virus from the duck mixing with human and swine viruses in one single cell in the pig's body. Imagine the commingling of DNA. Imagine a monster virus being born.

Eventually, the new virus nests in the pig's trachea. Anatomically, the pig's trachea is similar to that of the pig farmer.

"Once the virus is in the pig's trachea," Walters says, "it's halfway across the species bridge to man."

What finally produces a pandemic is the virus' unique genetic combinations — different from the kinds of seasonal flu viruses people are used to catching.

"We all have some partial protection against seasonal flu — even though 36,000 people still die from it every year," he says.

"But when one of those novel bugs leaps from animals to people, our immune systems are completely blind-sided."

Walters has coined a word for such health crises: "Ecodemics."

They often spring from ancient human agricultural practices. But they can come from a modern American factory farm, too, if the farm is near a pond or if pigs are fed contaminated feed.

"All the new diseases, except Legionnaires' (a bacteria that originates in water supplies), have that link."

They are nurtured by environmental degradation.

From a report by the Consortium for Conservation Medicine in New York:

"Climate change, chemical pollution, global trade, domestic animals, encroachment into wilderness areas and the overuse of antibiotics are some of the primary mechanisms through which humans are rapidly transforming host-parasite ecology worldwide."

Walters says the crisis is massive and the solutions elusive. But it comes down to this:

"Sanity in the production of our food."

USF professor is expert on tracking human infections to their animal sources 04/29/09 [Last modified: Monday, May 4, 2009 3:22pm]
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