Spring 2008

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Fight against infectious diseases spans from pigs to shrimp

Hank Harris has studied infectious diseases in pigs and shrimp for over four decades. He is currently studying genetic disease resistance and the nutritional value of distilled dried grain solubles for shrimp.

Hank Harris gently reaches into the salt-water tank resembling a giant ice cream pail and pulls up a shrimp more than six inches long. The translucent crustacean is large for a shrimp grown in a nonnatural setting.

“It’s more difficult to raise the larger shrimp in ponds or farms because of infectious diseases,” Harris says. “That’s why larger shrimp are more expensive.”

Harris, Iowa State professor of animal science and veterinary diagnostic and production animal medicine, has been studying infectious diseases since 1967. He became interested in shrimp after he was contacted by the Oceanic Institute in Hawaii in the 1990s. They asked about his work with pigs and realized they could apply those methods to shrimp.

“There are some interesting bacterial diseases in shrimp and there wasn’t much research being done at the time,” Harris says.

Shrimp are difficult to grow in ponds or farms because of disease, Harris said. About half the shrimp consumed in the United States are farmed in ponds along the coastal areas of North and South America and Asia.

The growing period for marketable shrimp is four to five months. Those shrimp can weigh up to 30 grams. Harris orders about 4,000 larvae shrimp every three months to restock the tanks.

There wasn’t much interest in shrimp research in Iowa, and why should there be? But then ethanol production began to boom, says Harris.

“The ethanol folks wanted to know if the byproducts from ethanol production could be used as a food source for shrimp,” Harris says.

To find the answer, Harris received a $40,000 grant from Midwest Grain Processors of Belmond, Iowa. He has also received funding from an Indonesian company, which supplies 10 percent of the world’s farmed shrimp market, to study infectious diseases and food sources. His research includes the search for genetic disease resistance and the nutritional value of distilled dried grain solubles for shrimp.

But what are the similarities in studying infectious diseases in pigs and shrimp?

“The lab procedures are almost identical for pigs or humans or shrimp. The similarities are in disease control. Like pigs, we begin by eliminating the pathogens that cause disease. And, like pigs, we separate the shrimp by age,” Harris says.

Harris has studied infectious diseases in swine for the past 40 years. During that time he and his colleagues have made multiple discoveries that have benefited the pork industry including:

• identifying the microscopic bacterium that caused swine dysentery in the 1970s
• developing a vaccine in 2005 to prevent Porcine Reproductive Respiratory Syndrome (PRRS), which causes infertility and reproductive problems in pigs
• isolating piglets after weaning, which formed the basis for multiple-site production, now an industry standard

Harris has a long list of accomplishments and awards. In 2005, Harris was included in the National Hog Farmer magazine’s top 50 men and women who have made a difference in the pork industry. He also received the College of Agriculture and Life Sciences Henry A. Wallace award in 2004, which honors individuals who have had widespread influence in agriculture.

Harris continues to be amazed at how diseases continue to evolve and change.

"Twenty years ago, the World Health Organization believed infectious diseases would be conquered," Harris says. "Infectious diseases continue to be a problem and it appears they will keep evolving. There are more types of diseases we have to contend with, and it's probably due to increases in population, how we travel and how we move and raise animals around the world. All those factors contribute to infectious diseases."