April 3, 2008
Vol. 38, No. 128

For more information, contact Rob Hossler, Wildlife Program Manager - Game Species, 302-735-3600, or Joanna C. Wilson, Public Affairs, 302-739-9902.

Delaware First in Nationwide Sampling for Avian Influenza

The Delaware Division of Fish and Wildlife, in cooperation with USDA-Wildlife Services, has taken the lead in the nationwide surveillance of migratory wild birds for avian influenza (AI). This year Delaware has already collected 2,697 AI samples from wild birds, 26 more than the closest cooperating state, Alaska.  

Avian influenza occurs in a number of different strains, with most strains being low pathogenic forms that naturally occur in wild birds and pose no serious risk to domestic poultry. In most cases, these strains cause no signs of infection or only mild symptoms in birds. 

To date, the highly pathogenic strain of avian influenza H5N1 found in Asia, Europe and Africa has not been detected in North America. Early detection has been identified as the key to minimizing the spread of the virus to domestic poultry and humans. The surveillance of wild migratory birds and monitoring their risk of introducing new viruses is one of many ongoing efforts aimed at early detection, thereby helping to prevent the spread of this disease if it were to appear in North America.

Rob Hossler, the Division’s AI program manager, commented on how tiny Delaware has been able to surpass larger states such as Alaska in surveillance efforts. “After the first year we were able to fine tune our capture techniques and sampling locations and with the assistance of USDA we also refined our target species list, both of which improved our sampling efficiency,” he said. 

Since the nationwide early detection strategy was introduced in 2006, Delaware has been a priority state for AI surveillance because of its importance as a wintering area for hundreds of thousands of migratory waterfowl; as a primary migration corridor for shorebirds; and as the heart of the Delmarva poultry production area.  

Because of these reasons, Delaware has obtained the maximum level of federal funding for surveillance. This federal funding was then supplemented by state appropriations the last two years, permitting Delaware to collect more than double the samples of most other states. Last year Delaware finished second among the 50 states cooperating in this nationwide effort. 

Hossler also noted that the Division becoming a member of the Delmarva Avian Influenza Task Force - comprised of the Delmarva Poultry Industry, the Delaware departments of Public Health, Agriculture, Natural Resources and Environmental Control, and the University of Delaware - served as an added incentive to improve sampling efforts.  

“Combined, these agencies have arguably the best ongoing avian influenza surveillance of commercial poultry nationwide, and it only seemed fitting that our wild bird surveillance program follow suit,” Hossler added. 

AI samples are being obtained from dead wild birds, hunter-harvested birds and live captured birds. Live birds are tested in the field, banded with numbered metal bands and released unharmed. A variety of species-specific capture techniques are used for wild birds including rocket and cannon nets, mist nets, various types of swim traps and roundups of flightless birds while molting. Hunter-killed birds are sampled at the hunter checking station and returned to the hunter. Dead birds are collected in the field, sampled at a field lab and landfilled.   

 “In terms of sampling efficiency, our AI crew has become comfortable enough with the sampling protocol that only one staff member is required to sample hunter-harvested birds and those found dead of other causes. However, live captures can become quite complicated and challenging, so a team of two to four is usually required,” Hossler explained. 

Delaware’s AI samples are tested at the Allen Avian Biosciences Laboratory at the University of Delaware, one of 46 nationally approved labs authorized to do the testing. Samples that test presumptive positive for the H5 or H7 strains of AI in the UD lab are shipped to the National Veterinary Services Laboratory in Ames, Iowa, where further testing confirms the finding and determines whether it is high or low pathogenic.   

To date, Delaware’s AI program has collected samples from 41 species of birds. Approximately 22 percent of these samples tested presumptively positive for some variant of avian influenza. However, since Delaware’s testing program began in 2006, only 23 samples (including eight in 2007-08), or 0.4 percent, tested positive for a strain of influenza which could be perceived as a threat to the poultry industry and required further testing at the national lab in Iowa. None of these were the Asian bird flu strain.

Highly pathogenic H5N1, commonly called the Asian bird flu, has been detected in wild birds and poultry in 61 countries and is the strain responsible for the culling of poultry flocks in Asia and Europe, as well as 373 human cases, with 236 resulting in death.

For more information on the Delaware Division of Fish and Wildlife’s avian influenza monitoring program, please visit www.dnrec.delaware.gov/Info/Pages/AvianFluFacts.aspx.