Is a "perfect storm" brewing for an avian flu outbreak in Delaware? UD is part of a poultry health network working to protect the state's $3.2-billion poultry industry from the disease.
Waterfowl — ducks, geese, swans and shorebirds — commonly get avian flu, but they don't get sick. However, they become natural carriers of the disease as they migrate along the world's flyways, including the Middle Atlantic Flyway, where Delaware is a prime pitstop.
For chickens and turkeys, the flu can be fatal.
"Much like people do when they get influenza, chickens and turkeys become listless, cough and suffer other respiratory distress," says Jack Gelb, chairman of UD's Department of Animal and Food Sciences and director of the Avian Biosciences Center. "Avian influenza is a highly contagious disease, and if the virus is particularly virulent, high bird mortalities will occur."
Poultry powers Delaware's economy in a big way. Delaware farmers sent over 231 million broiler chickens to market in 2009, according to Delmarva Poultry Industry Inc., a regional trade association. A study released earlier this year by the UD Department of Food and Resource Economics estimates the poultry industry's value at $3.2 billion — it is the single largest contributor to the state's $8-billion agricultural industry.
Waterfowl defecate as they fly overhead or waddle on land, putting poultry flocks potentially at risk if a farmer accidentally gets feces from a flu-infected bird on a shoe or equipment and walks inside a poultry house. And that's just one of a number of scenarios, Gelb says. Birds bought at live markets, backyard flocks and the threat of bioterrorism also concern the triumvarite of industry, government, and university partners working to monitor poultry health.
In 2004, the H7N2 strain of avian influenza struck three farms on Delmarva and was quickly brought under control through the teamwork of state governments in Delaware and Maryland, the Delmarva poultry industry, and the University of Delaware and the University of Maryland. The U.S. Department of Agriculture (USDA) hailed the response as a "national model."
Although the highly pathogenic H5N1 avian influenza has not caused problems in the United States, that virulent strain has impacted poultry in Asia, Africa, Europe and the Middle East. Some people living in close contact with infected flocks in those countries have gotten sick and died. Health officials are wary that the virus could mutate to infect humans and create a pandemic, as humans have no immunity to the disease.
UD's Avian Biosciences Center in the College of Agriculture and Natural Re-sources encompasses two major laboratories and teams of scientists and extension agents working on a comprehensive program of poultry disease research, surveillance and outreach. Gelb oversees the program.
Lasher Laboratory, at the Georgetown campus, serves as the primary poultry diagnostic lab in Delaware. Technicians there utilize the real-time reverse transcription polymerase chain reaction (rRT-PCR), a fast, highly sensitive DNA test for avian influenza. The lab provides comprehensive diagnostic services to commercial poultry producers — a representative sample of birds from every farm flock in Delaware is tested before being sent to market. The testing also is available to small non-commercial hobby and backyard flocks.
At the Charles C. Allen Laboratory, a federally certified biocontainment facility on UD's main campus in Newark, research yields new discoveries relating to avian influenza and other infectious poultry diseases. Among multiple safeguards, the high-tech laboratory's biocontainment rooms are maintained under "negative pressure," meaning that air continually is drawn into the rooms, and no air can escape without passing through a series of HEPA filters capable of trapping viruses.
The world-class facility, one of only a handful in existence, focuses on epidemiology, pathogenesis (the tracking down of a disease's origin) and vaccine development. Among the projects under way there, Gelb and Brian Ladman, an associate scientist and part-time doctoral student in animal science, are working to uncover how avian influenza evolves from a low-pathogenic to a high-pathogenic virus. The research is supported by the USDA's Avian Influenza Coordinated Agricultural Project.
The scientists attempted to adapt low-pathogenic viruses to different poultry species to see how the avian influenza viral populations change depending on the host — whether a duck, chicken, turkey or quail. The virus was adapted by infecting each species ten times. Then using the powerful tool of "deep sequencing" at the Delaware Biotechnology Institute, which decoded tens of millions of gene sequences in a single computing run over several days, the researchers sought to identify "snips,' single nucleotide polymorphisms (SNPs), which are "single letter" variations in DNA sequence within the genome.
"We found some pretty interesting changes in the low pathogenicity populations of the adapted viruses in chickens, where it had taken a step toward becoming a high-pathogenic virus," Ladman says.
The telltale sign, Ladman says, was a mutated amino acid occurring at the cleavage site of hemagglutinin (H), a key surface protein the virus uses to infect its hosts.
Ladman is now analyzing the viral genetic data across the four poultry species to determine how unique this mutation is, and when it first occurs in chickens. The answers may help illuminate the inner workings of influenza and help researchers predict if and when a low pathogenicity form of the virus might mutate to the virulent high-path form.
"Flu is everywhere — it's found naturally in certain wild animals and humans hosts all the time and should not be a concern," Gelb notes. "We're trying to understand the ecology of avian influenza and how these viruses are able to find new hosts."
An outbreak of the low-pathogenic H7N2 avian flu caused a scare on the Delmarva Peninsula in 2004, but was tamped down quickly and limited to three farms — a feat attributed to rapid diagnosis, quarantine, proper dead bird composting and decontamination.
This efficient response and control — credited to the teamwork of state government, poultry growers, the Delmarva Poultry Industry Inc., and the University of Delaware and the University of Maryland — has been hailed as a "national model" by the U.S. Department of Agriculture (USDA).
UD researchers continue to share the approach with colleagues in the U.S. and abroad via technical assistance programs in Romania, Bulgaria, Turkey and India. The Emergency Poultry Disease Response Certificate Program (ag.udel.edu/abc/epdr.html) is an internationally recognized short course offered annually on campus.
In 2010, UD tested nearly 4,000 samples as part of the USDA and poultry industry program that screens every commercial broiler flock prior to marketing to ensure
they are influenza-free.
Additionally, UD's Avian Biosciences Center has tested more than 10,000 samples from live and dead wild migratory birds as part of an early warning and detection program that has beenin place since 2005, led by the Delaware Department of Natural Resources andEnvironmental Control, with support
from USDA and the Department of the Interior.
Rising food costs, a dimmed economy, and the desire for locally grown food have sparked a backyard gardening movement in the United States, and an increasing number of cities are now allowing chickens to be grown within city limits.
According to the University of Delaware's Avian Biosciences Center, biosecurity is especially critical for owners of backyard flocks since these birds sometimes are raised outside and may come in contact with wild birds and migratory waterfowl. Restricting access to your property and birds minimizes the risk of avian influenza infection.
If you have come in contact with wild fowl or other birds, the experts recommend that you bathe and change your clothes and footwear before caring for your flock. Hunters must be particularly aware of where they have been and how they may interact with domestic poultry.
Know the warning signs of disease, and report any sick birds to your state department of agriculture or the USDA's toll-free hotline at 1-886-536-7593.
Jack Gelb, director of UD's Avian Biosciences Center (standing), and research associate Brian Ladman inject chicken eggs with avian influenza virus. The scientists are working to uncover how avian influenza evolves.
So what does H5N1 mean in the influenza world?
There are three types of influenza viruses — A, B and C. The H5N1 avian influenza is an A virus.
Only influenza-A viruses are classified by subtypes based on two primary proteins on their surface: hemagglutinin (H) and neuraminidase (N). The numbers in the name reflect a genetic change in the virus.
Influenza-A subtypes are classified by strains, which are further classified as low pathogenic or high pathogenic. To date, only H5 and H7 subtypes have shown the potential to shift from low to high pathogenic.
It seems that the only constant about influenza viruses, whether in chickens, humans or other species, is that they are always changing.
That's why the need for new human vaccines is re-evaluated each year based on the flu viruses in circulation, and why health officials recommend that you get a new flu shot each year. To learn more, visit the Centers for Disease Control (CDC) website at www.cdc.gov.