Keeping Emerging Diseases and Invasive Species Out

Since the first ships made passage across mysterious oceans, trade has ferried bounty from country to country. Unfortunately, in addition to their treasures, these ships also carry hidden cargo -- insects, plants, animals and diseases that have the potential to become pests to foreign lands.
Ronald Stahley, Director of Public Works and Chairman, Board of Supervisors, North Whitehall Township, Lehigh County

Ronald Stahley, Director of Public Works and Chairman, Board of Supervisors, North Whitehall Township, Lehigh County

"We are extremely grateful to the Penn State Cooperative Extension staff in Lehigh County, who led the way in our training, awareness and education. The effectiveness of our mosquito eradication program would be greatly diminished were it not for their invaluable advice and counsel."

Today, globalization dramatically increases the rate of international trade; as a result, the influx of dangerous, non-native pests and diseases is on the rise. When new threats emerge, Penn State's College of Agricultural Sciences, often working in partnership with state and federal agencies, acts quickly to educate the public and find cost-effective ways to manage emerging diseases and invasive species that endanger the health and well-being of Pennsylvania's people, animals, economy and natural resources.

The Payoff

There's a new bug in town

Before 1999, West Nile encephalitis, a disease caused by West Nile virus (WNV), hadn't been documented in the Western Hemisphere, but that year an outbreak occurred in the New York City metropolitan area. The Centers for Disease Control and Prevention confirmed 62 human cases of West Nile encephalitis in New York, including seven deaths. Several types of mosquitoes transmit WNV by biting and infecting wild birds, but poultry, horses and other mammals, including humans, can become infected if bitten by an infected mosquito. Pennsylvania's first cases of WNV were confirmed by October 2000. Unfortunately, little information about the virus was available to help an increasingly alarmed public. So, Penn State specialists began an intensive effort to educate people about WNV. The team developed a comprehensive website (www.pested., which is accessed 11,000 times per year. Presentations, exhibits, brochures, publications and television programs were developed and used throughout the state -- one exhibit at the Philadelphia Flower show provided information to 300,000 visitors. In addition, WNV contacts now are available in all 67 county cooperative extension offices. And, working in conjunction with state agencies, a WNV surveillance team has been established statewide. As a result, millions of Pennsylvanians have learned how to help reduce area mosquito populations, take preventative measures to avoid being bitten, and assist in WNV surveillance efforts.

A pox on your peaches

In 1999, the plum pox virus was discovered in Pennsylvania, the first occurrence of the disease in North America. Plum pox devastates stone fruit, such as peaches, plums, nectarines and cherries, and its arrival threatened to destroy the state's $25 million-per-year industry and, potentially, stone-fruit production nationwide. Penn State specialists teamed with state and federal agencies, growers, legislators and citizens to develop a rapid-response team to stop the spread of the virus. Special meetings bringing growers and scientists together were organized, and educational materials and a website were developed. As a result, growers cooperated with scientists to identify infected trees and destroy them. To assist with their financial loss, special funds were secured to help these farmers stay in business. Thanks to this quick and collaborative response, Pennsylvania's plum pox outbreak may be over. To make sure, surveillance and remediation will continue over the next few years. An example of a PPV-infected peach.

These are profit killers

Most people have heard or read about foot and mouth or mad cow disease. Foot and mouth disease is one of the most contagious animal diseases known. Fortunately, it hasn't been seen in the United States since 1929. Mad cow disease has been found primarily in Europe, but it has also been identified in cattle in Asia, the Middle East, Africa and South America. Both of these diseases have the potential to devastate Pennsylvania's $1 billion livestock industry. The key to protection is education, quarantine and improved farm biosecurity. Working in conjunction with the Pennsylvania Department of Agriculture, Penn State scientists and extension educators have played a key role in developing and disseminating information to keep our state free from these diseases. Thanks to the development of websites, publications and other materials, as well as educational seminars conducted for farmers, agricultural professionals and veterinarians across the state, neither foot and mouth nor mad cow diseases have been found Pennsylvania.

Have boat, will travel

Zebra mussels are inadvertently captured when ships draw water into their ballasts. Later, when the ballasts are emptied somewhere else, the mussels get a new home. Hitchhiking this way, zebra mussels have been spread from their native Caspian Sea to Europe and the Great Lakes. Notorious for their ability to form huge colonies that block water flow, zebra mussels can seriously damage power plants, public water systems and industrial facilities. They also threaten native species and may have a negative impact on water quality. With zebra mussels now reported in more than 20 states including Pennsylvania, Penn State specialists have developed educational programs for boat owners, shipping companies and others who are key to controlling the spread of the mussels. Research also is planned to determine if they pose a threat to water quality in Lake Erie.

It's pretty, but..

Purple loosestrife -- a beautiful, exotic weed unintentionally imported from Europe -- is a severe threat to North American wetlands and their native plants and animals. Scientists and extension specialists teamed with U.S. and European agencies and discovered several insects that decimate loosestrife without harming native plants. These insects now are being tested at sites in Pennsylvania and throughout the country.

For more information, contact either Penn State Cooperative Extension at 814-863-3438 or the Office of Research and Graduate Education at 814-865-5410, or search for the topic on the College of Agricultural Sciences' website.