Manure Disposal Following an Outbreak of Avian Influenza on a Commercial Poultry Farm
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By Darrell W. Trampel, DVM, PhD, Extension Poultry Veterinarian and Poultry Diagnostician, Iowa State University
What is avian influenza?
Avian influenza (AI) is a viral disease that infects almost all species of birds. It is caused by a Type A Influenzaviru. Type A influenza viruses are found in humans, birds, swine, horses and some other mammalian species. Influenza viruses are further classified into subtypes based upon two external glycoprotein structures: hemagglutinins (H) and neuraminidases (N). There are 16 possible hemagglutinins and nine possible neuraminidases. Influenza viruses with H5 and H7 surface structures have the potential to change from a low pathogenic virus into a highly pathogenic virus capable of causing death in most poultry infected.
Why is avian influenza important and can it affect other animal species in addition to poultry?
Since December 2003, a highly pathogenic H5N1 avian influenza virus has spread through Asia, Europe and six countries in Africa. It has been estimated that more than 200 million poultry have been killed by the H5N1 virus or by slaughter eradication programs.
The H5N1 avian influenza virus has been transmitted from infected birds to mammals. In addition to wild birds and domestic poultry, the H5N1 virus has infected domestic cats, tigers, leopards, dogs, swine and humans. Approximately 50 percent of humans infected have died.
How is avian influenza transmitted and how long can the avian influenza virus survive in manure?
Fecal-oral transmission. AIV is excreted primarily through the feces and to a lesser extent by secretions from the nose and mouth. This virus can survive in water for many days. In feces, it can survive for 30 to 35 days at 4 degrees C (39.2 F) and for seven days at 20 degrees C (68 F). Avian influenza viruses in liquid manure have been shown to remain viable for 105 days during the winter.
Aerosol transmission. Avian influenza virus can be transmitted to a lesser degree by nasal and respiratory tract excretions. Low pathogenic AI replicates especially well in the upper respiratory tract.
How does avian influenza spread between flocks ?
Humans are the primary spreaders of AIV between flocks. Feces and respiratory secretions containing potentially millions of avian influenza virus particles are carried to different locations by contaminated people (clothing, footware and hands) and contaminated equipment. Flock owners should not share equipment, such as that used for manure handling, bird catching, vaccination, loading or transport.
Equipment contaminated by feces and respiratory secretions containing AI viruses can readily transmit the disease. Potential carriers include truck, pick-up and car tires on vehicles driven by feed delivery, live-haul to processing plants, flock owners, farm workers, utility (electricity, water) workers, catching crews, vaccination crews, artificial insemination crews (turkeys), servicemen, manure applicators or veterinarians. Fecal dust containing virus particles and contaminated feathers may be disseminated by air currents. Careful disposal of manure and dead birds is critical.
How can this virus be destroyed?
Heat, extremely low or high pH, and dryness can inactivate avian influenza viruses. Heating buildings to 90 to 100 degrees F for one week has been used to inactivate influenza viruses. In addition, infectivity of influenza viruses is destroyed by exposure to organic solvents and detergents. Virkon S is a disinfectant frequently used to disinfect premises after an outbreak of avian influenza has occurred.
What will happen if a highly pathogenic avian influenza virus is found on a poultry farm?
The State Veterinarian will immediately quarantine the farm and establish a surveillance zone around the quarantine zone. USDA’s Animal and Plant Health Inspection Service (APHIS) will be notified and the disease will be quickly eradicated. All poultry infected by or exposed to the virus will be humanely euthanized and carcass disposal will be carried out by burial or composting. After an approved cleaning and disinfection process has been completed, Iowa’s Department of Agriculture and Land Stewardship will require a mandatory down time of no less than 30 days.
After the mandatory down time requirements are met, sentinel birds will be introduced to determine if viable influenza virus is still present. Sentinel birds will remain for two specific pathogen incubation periods (30 days) and be monitored for clinical signs of the disease. After the State Veterinarian has given permission to repopulate the farm, new birds on the farm will be monitored serologically.
Can manure be removed after poultry in a house that has been infected with avian influenza?
Manure can be removed from an infected house only after permission has been granted by the State Veterinarian. Articles that cannot be disinfected and pose a risk of disease transmission, such as feed, poultry manure and litter must be disposed of by an approved method such as burial or composting. Whenever possible, disposal of these materials will be done on the affected farm so that transport of infective virus to other locations does not occur.
Determination of an appropriate on-site burial location for contaminated manure and litter should be done by Iowa’s Department of Natural Resources according to their carcass disposal plan. The plan requires a plat map description and the 911 address of the premises to allow the development of maps that will help determine if an appropriate area for manure and litter disposal is on or close to the infected premises. In the event that there is no approved burial area on the premises, the procedure will be to look at other areas in the vicinity, primarily other infected premises, dangerous contact premises or adjacent crop land.
In some cases, contaminated poultry manure and litter may need to be loaded and hauled to an approved landfill. A site for poultry manure disposal would be designated away from the working face of the landfill. A track hoe would be required to dig a single trench in the waste pile where trucks would dump the poultry manure and litter, which would immediately be covered with a least two feet of solid waste.
In-house composting provides a controlled environment that reduces the need to move contaminated manure and litter and protects compost piles from inclement weather which aids in providing more satisfactory composting temperatures for pathogen inactivation. In properly constructed piles, temperatures are expected to reach 120 to 160 degrees within the first 10 days. Research has shown highly pathogenic avian influenza viruses will be inactivated after 10 days of composting.
Ag-Bag composting is a method of composting done in special composting bags that are ventilated during the composting process. Using special equipment, contaminated manure and litter can be loaded into long plastic bags, which are then ventilated as the materials are composted. Advantages of this procedure include 1) inactivation of pathogens on site, 2) composted material can be used after destruction of pathogens and 3) barns may be cleaned and disinfected as soon as poultry are removed.
What can a commercial manure applicator do to prevent the spread of avian influenza?
Clean and disinfect vehicles and equipment. Clean the undercarriage and tires of vehicles with a strong detergent, then apply disinfectant to kill disease-causing micro-organisms that can linger on surfaces. Delivery trucks and other vehicles should carry a sprayer of disinfectant in the cab so that tires and wheels can be disinfected before entering and leaving a farm. Additional biosecurity can be obtained by taking vehicles through a car wash between farm visits to remove any manure or fecal dust that could potentially adhere to the exterior surfaces.
Wear sanitized coveralls and boots. Drivers should carry disinfectant sprays (Lysol or a similar disinfectant) in their vehicles so that shoes and floormats can be disinfected when entering an automobile, pickup or truck.
Do not enter poultry barns that are not undergoing clean out. Do not visit other poultry farms until you have changed clothing and your vehicle has been cleaned and disinfected.
How can a commercial manure applicator learn more about avian influenza?
More information is available at the following Iowa resources for avian influenza
This Iowa State University fact sheet provides information for farmers and pet owners (pdf).
Here is a list of national Web sites.
USDA’s Web site provides fact sheets and information about food safety and reporting suspected cases.
The U. S. Department of Health and Human Services Web site monitors human outbreaks around the globe and offers planning tools for individuals and businesses.
The Centers for Disease Control’s Web site addresses specific groups such as the people working in the poultry industry, persons involved in eradication activities and persons with possible exposure.
The National Wildlife Health Center Web site deals with migratory birds and is a good source for maps and additional fact sheets.The U. S. Department of Labor Web site offers guidance for protecting farm workers, animal handlers, food handlers and travelers against avian flu.