Biosecurity and Infectious Laryngotracheitis in Alberta Dr. Keith McMillan, D.V.M., M.VSc., ACVP Vice President, Lilydale Foods N.D. Bragg Wever, D.V.M., M.Sc

Infectious laryngotracheitis (ILT) has proved to be a persistent cause of concern in the poultry industry. The disease is a viral respiratory infection caused by herpesvirus and affects fowl and pheasants. ILT has an incubation period of approximately 6-12 days and is spread through aerosol and/or direct contact. The virus enters the body through the upper respiratory tract and conjunctiva. Infection may be mild, severe, or asymptomatic. Clinical signs vary and can include but are not limited to severe respiratory distress and coughing up of blood. Birds may also show conjunctivitis and slightly swollen heads.

All ages of fowl are susceptible and the disease is most commonly seen in birds 3 to 9 months of age. However, very young chicks are highly susceptible to the disease. Transmission through the egg is not known to occur and newly hatched chicks are free from infection. However, the trays and equipment which were on the farm can serve to spread the virus. Therefore, strict hatchery and farm biosecurity is required when ILT or any other disease is identified. Accurate diagnosis is needed to ensure that infected sites are identified promptly. In the advent of an outbreak, immediately call a veterinarian. Veterinarians will diagnosis disease(s) based on the history, clinical presentation, post-mortem, histology, serology, virus isolation, and/or culture and sensitivity.

ILT remains a potent threat to poultry production. The fear associated with ILT is that once contamination is established, it is often difficult to eradicate the disease particularly on multi-aged operations. In general, biosecurity has been breeched when an outbreak occurs. To sum up, prevention is better than treatment, and the best protection against the virus lies in good management practices and an effective biosecurity program.

The infectious larynotracheitis outbreak in July 2002 in Southern Alberta heightened the importance of biosecurity in the poultry industry. This session will be predominantly an open floor discussion on the aspects of biosecurity. The following diagrams are illustrative of how biosecurity measures are necessary in order to ensure effective containment of a disease during an outbreak situation. Without proper measures, it is quite possible for any disease to quickly and rapidly spread from one site to multiple sites. This is illustrated by the amount of traffic flow of visitors from one farm to another.

Biosecurity, in simple terms, means keeping disease away from poultry and keeping poultry away from disease causing agents. Initiating and maintaining a biosecurity program is an important aspect of a poultry health program. By reducing the exposure to disease causing agents, you can help prevent disease(s) from occurring in flocks. There are several different types of disease agents or pathogens. They include viruses, bacteria, and fungi. In addition, parasites found internally and externally can also cause disease. The control of these parasites is considered an important part of a biosecurity program.

Considering the economic investment in a large poultry operation, security precautions are a small price to pay to keep disease away from a flock. Therefore, farm biosecurity is essential, and it must be implemented and religious followed. Traffic flow needs to be consistent in order to minimize potential cross-contamination. Controlled access and restricted zones need to be identified and complete biosecurity measures need to be taken each and every time this imaginary line is breeched in order to maintain an effective biosecurity program.

A biosecurity program is an effective but cheap means of disease control. The three major components to a biosecurity program are isolation, traffic control, and sanitation. Isolation in a biosecurity program refers to the segregation of birds within a controlled environment or a restricted zone. This serves to isolate the birds as well as to keep unwanted animals out. Traffic control on and within the farm needs to be assess and limited in an effective biosecurity program. The disinfection of materials, people, and equipment entering the farm and the cleanliness of the personnel on the farm is addressed in the sanitation aspect of a biosecurity program.

Infectious disease can be spread from farm to farm by:

• introduction of diseases birds

• introduction of healthy birds who have recovered from the disease but are now carriers

• shoes and clothing of visitors and/or personnel who move from flock to flock

• contact with inanimate objects (fomites) that are contaminated with disease organisms

• carcasses of dead birds that have not been disposed of properly

• impure water, such as surface drainage water

• rodents, wild animals, and birds

• insects

• contaminated feed and feed bags

• contaminated delivery trucks, rendering truck, live hauling trucks

• contaminated premises through soil or old litter

• air-borne fomites

• egg transmission

The introduction of new birds and traffic pose the greatest risk to overall bird health and the integrity of a biosecurity program. Each biosecurity program needs to be developed to meet individual farm needs. Economics, common sense and the relative risk are all factors that aid in the assessment of the degree of biosecurity which is practical for each farm. Biosecurity programs need to be regularly reviewed and adjusted according to these factors.

By following these biosecurity recommendations, you can help to ensure that exposure to disease-causing agents is reduced although not eliminated.

Accurate diagnosis is needed to ensure that infected sites are identified promptly.
In the face of an outbreak, alert anyone who comes in contact with your farm; by all means do not venture into the poultry industry. Stay away from popular meeting places and areas of increased poultry traffic. Infection tends to persist on contaminated sites until they are totally depopulated or an appropriate treatment plan is instituted which may include vaccination. Following depopulation, through disinfection of all buildings and equipment is pivotal to break the cycle. Once birds are re-introduced, strict adherence to a structured biosecurity programs must be observed to prevent subsequent re-infection of the site.

The success of a biosecurity program ultimately depends upon everybody working towards a team effort and requires a constant every revolving commitment.