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Avian Influenza

Avian influenza (AI) is caused by type A influenza virus. The symptoms can vary from a mild disease with little or no mortality to a highly fatal, rapidly spreading epidemic depending on the infecting virus strain, host factors, and environmental factors.

Natural Hosts

More avian influenza viruses have been isolated from ducks than any other species although most free-flying birds may also be infected, including shorebirds, gulls and other seabirds. Waterfowl are more resistant to avian influenza than are domestic poultry. Viruses that cause no obvious disease in waterfowl can be highly pathogenic (rapidly fatal) in domestic poultry. Among domestic poultry species, turkeys are more frequently infected than are chickens.

Transmission of AI

Waterfowl act as a reservoir of avian influenza virus by carrying the virus in their intestinal tract and shedding it in their feces. Avian influenza viruses are spread to susceptible birds through nasal and respiratory secretions and from contact with the feces of infected birds.

Signs of disease

Signs of avian influenza are extremely variable. In some flocks the only evidence of the infection is seroconversion i.e., the birds develop a detectable antibody to AI. AI can also be manifest as respiratory, enteric, reproductive or nervous system disease. Decreased food consumption and decreased egg production are among some of the earliest and most predictable signs of disease. Signs including coughing, sneezing, ruffled feathers, swollen heads, nervous signs like depression, and diarrhea may occur together or singly. In some cases, birds die rapidly without evidence of disease.

Prevention and control measures

Wild birds and their excreta should be considered a potential source of avian influenza. Preventing direct contact with free-flying birds and protecting domestic poultry from contact with the feces of wild birds is an important way to prevent the transmission of avian influenza.

Live bird markets have been an important source of avian influenza, especially on the East coast of the U.S. It is important to avoid live markets, educate employees about the dangers posed by these markets, and prevent the spread of disease from these markets to your flock by preventing any contact.

Infected birds shed virus in saliva, nasal secretions and feces in the first two weeks of infection. Four weeks after infection, virus can no longer be detected. Hence, prevention is best accomplished by preventing contact between newly infected and susceptible birds. Biosecurity is a first line of defense. Avian influenza can be spread from infected birds through the transfer of feces especially on contaminated equipment and clothing. Controlling the traffic between infected and uninfected birds is essential.

Cleaning and disinfection of poultry houses.

Influenza viruses are very sensitive to most detergents and disinfectants. They are readily inactivated by heating and drying. However, flu viruses are well-protected from inactivation by organic material and infectious virus can be recovered from manure for up to 105 days. Complete removal of all organic material is part of any effective disinfecting procedure.

Contaminated houses are heated for several days to inactivate virus. Organic material is removed followed by complete cleaning and disinfecting of all surfaces. Contaminated litter and manure is problematic and should be composted or buried to ensure that it does not spread infectious virus.

Diagnosis of Avian Influenza

The Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) at the Department of Pathobiology and Veterinary Science, University of Connecticut, 61 North Eagleville Road, Storrs, CT 06269 is accepting any sick or dead bird showing signs of avian influenza or related diseases for AI investigation. The CVMDL will do the diagnosis of the cause of death in birds (backyard poultry, pheasant, partridges, quail or wild bird species) at no charge. Funds to offset the coast of pathology services are provided by the State Veterinarian.

Mazhar I. Khan, DVM, MPVM, PhD
Extension Avian Veterinarian
Department of Pathobiology & Veterinary Science
University of Connecticut, Storrs, CT 06269-3089
Phone: 860-486-0229
Fax: 860-486-2794
Email: mazhar.khan@uconn.edu

Avian influenza (AI) is caused by type A influenza virus. The symptoms can vary from a mild disease with little or no mortality to a highly fatal, rapidly spreading epidemic depending on the infecting virus strain, host factors, and environmental factors.

Natural Hosts

More avian influenza viruses have been isolated from ducks than any other species although most free-flying birds may also be infected, including shorebirds, gulls and other seabirds. Waterfowl are more resistant to avian influenza than are domestic poultry. Viruses that cause no obvious disease in waterfowl can be highly pathogenic (rapidly fatal) in domestic poultry. Among domestic poultry species, turkeys are more frequently infected than are chickens.

Transmission of AI

Waterfowl act as a reservoir of avian influenza virus by carrying the virus in their intestinal tract and shedding it in their feces. Avian influenza viruses are spread to susceptible birds through nasal and respiratory secretions and from contact with the feces of infected birds.

Signs of disease

Signs of avian influenza are extremely variable. In some flocks the only evidence of the infection is seroconversion i.e., the birds develop a detectable antibody to AI. AI can also be manifest as respiratory, enteric, reproductive or nervous system disease. Decreased food consumption and decreased egg production are among some of the earliest and most predictable signs of disease. Signs including coughing, sneezing, ruffled feathers, swollen heads, nervous signs like depression, and diarrhea may occur together or singly. In some cases, birds die rapidly without evidence of disease.

Prevention and control measures

Wild birds and their excreta should be considered a potential source of avian influenza. Preventing direct contact with free-flying birds and protecting domestic poultry from contact with the feces of wild birds is an important way to prevent the transmission of avian influenza.

Live bird markets have been an important source of avian influenza, especially on the East coast of the U.S. It is important to avoid live markets, educate employees about the dangers posed by these markets, and prevent the spread of disease from these markets to your flock by preventing any contact.

Infected birds shed virus in saliva, nasal secretions and feces in the first two weeks of infection. Four weeks after infection, virus can no longer be detected. Hence, prevention is best accomplished by preventing contact between newly infected and susceptible birds. Biosecurity is a first line of defense. Avian influenza can be spread from infected birds through the transfer of feces especially on contaminated equipment and clothing. Controlling the traffic between infected and uninfected birds is essential.

Cleaning and disinfection of poultry houses.

Influenza viruses are very sensitive to most detergents and disinfectants. They are readily inactivated by heating and drying. However, flu viruses are well-protected from inactivation by organic material and infectious virus can be recovered from manure for up to 105 days. Complete removal of all organic material is part of any effective disinfecting procedure.

Contaminated houses are heated for several days to inactivate virus. Organic material is removed followed by complete cleaning and disinfecting of all surfaces. Contaminated litter and manure is problematic and should be composted or buried to ensure that it does not spread infectious virus.

Diagnosis of Avian Influenza

The Connecticut Veterinary Medical Diagnostic Laboratory (CVMDL) at the Department of Pathobiology and Veterinary Science, University of Connecticut, 61 North Eagleville Road, Storrs, CT 06269 is accepting any sick or dead bird showing signs of avian influenza or related diseases for AI investigation. The CVMDL will do the diagnosis of the cause of death in birds (backyard poultry, pheasant, partridges, quail or wild bird species) at no charge. Funds to offset the coast of pathology services are provided by the State Veterinarian.

Mazhar I. Khan, DVM, MPVM, PhD
Extension Avian Veterinarian
Department of Pathobiology & Veterinary Science
University of Connecticut, Storrs, CT 06269-3089
Phone: 860-486-0229
Fax: 860-486-2794
Email: mazhar.khan@uconn.edu