Mammals capable of transmitting avian influenza to poultry

Researchers have known for some time that a wide range of wild mammals, including raccoons and foxes - common visitors to farms and waterways across Delmarva - can be carriers of avian influenza.

More recently, however, researchers confirmed that some mammals are not only carriers, but that they also can transmit the virus to birds, raising new questions about how the disease may move in the environment and between farms.

“When wildlife and poultry interact and both can carry and spread a potentially damaging agricultural pathogen, it’s cause for concern,” said research wildlife biologist Dr. Jeff Root, one of several researchers from the National Wildlife Research Center, part of the USDA-APHIS Wildlife Services program, studying the role wild mammals may play in the spread of avian influenza viruses.

This month the agency issued its latest research update on the topic, highlighting experiments in which Root and his team demonstrated that skunks and rabbits can become infected with and shed avian influenza virus, which subsequently infected mallard ducks.

The risks from mammals frequenting areas in and around poultry farms should be taken into consideration when crafting biosecurity plans, according to the full NWRC study published in late 2015. One of the most effective ways to reduce the number of animal visitors is to use freezer collection units for routine mortality, instead of composting.

“Proper management of bird mortality is an important (often overlooked) part of biosecurity. Freezers can help growers by providing a simple method to dispose of the birds,” said Dr. Jonathan R. Moyle, an associate professor and extension poultry specialist at the University of Maryland. “Not only do freezers prevent predators from accessing the carcasses, but they can also help reduce insects, which can also be vectors of disease.”

Composting sheds attract scavengers including buzzards, foxes, raccoons, birds and feral cats. Those same animals also visit local waterways where they can come into contact with migratory waterfowl, known carriers of disease. In 2004, retired University of Delaware poultry specialist Bud Malone observed evidence of all of those scavengers visiting compost bins on farms that were infected with low pathogenic avian influenza.

By disposing of routine mortality in sealed freezer collection units, the food source is eliminated, significantly reducing the number of animals and flies on the farm and the risk of transmission.

“We don’t have buzzards on that farm anymore. We don’t have any wildlife in there trying to get in to the birds,” said Brent Willin of State Line Farms after switching from composting to freezer collection units. “The fly issues are drastically reduced.”

Recent trends in the evolution of the virus reaffirm the need to assess multiple facets of farm-scale biosecurity of poultry operations, wherein all routes of viral intrusion, even those [previously] thought to be unlikely, are addressed, according to the NWRC study. The old method for managing mortality is one of those routes that should be reassessed in the wake of this new research.

Though introduced on Delmarva only a few years ago, freezer units have been used by growers in other regions of the country for decades. Routine mortality is placed inside specially designed collection units available for purchase from local ag-equipment retailers. A customized collection vehicle arrives between flocks to empty the units.

The practice, which was originally developed to help reduce the amount of high-phosphorous material being generated by composting, is an approved nutrient management method in all three states, making it eligible for cost-share programs.

Growers switching to this practice have been able to greatly reduce the time and money they previously spent on composting, realizing thousands of dollars a year in operational savings.

Nonmonetary benefits include elimination of the smells, flies and scavengers associated with composting, so the grower and the grower’s neighbors enjoy a greatly improved quality of life. In fact, DPI added freezer units to its list of Best Management Practices for Good Neighbor Relations. For more information, go to FarmFreezers.com.