Infectious Laryngotracheitis
What is it?
Infectious laryngotracheitis (commonly known as ILT) is a viral
respiratory disease that affects the trachea of chickens, pheasants and peafowl.
It’s a contagious disease with a varying degree of clinical signs; different
strains of ILT are capable of producing disease in a variety of forms. The mild
strains may not result in mortality, yet can have impacts like a drop in egg
production. Severe strains are more likely to cause visible clinical signs and high
mortality. Birds infected with or vaccinated for ILT become carriers of the
virus for the remainder of their life.
What are the clinical signs?
The disease typically takes one to two weeks to become
noticeable in birds. Generally, birds will exhibit swollen watery eyes, decreased
food and water consumption, blood on beak, neck extension, and a decrease in
egg production. Affected birds will have a nasal discharge and a mild rattling
noise on breathing that is often accompanied by gasping and coughing. In severe
forms, the breathing can become very labored and blood stained mucus is often
expelled. Mortality can be severe (90 to 100 percent) with virulent strains.
How is it transmitted?
The virus is shed from infected or vaccinated birds. It can
become airborne and contaminate litter and equipment through birds’ secretions
and excretions. The virus can also spread via workers’ boots or clothing if
proper biosecurity protocols are not followed. Contaminated hauling trucks and
litter spreading equipment have been linked to ILT epidemics in poultry. Birds
that have recovered from ILT carry the virus and can shed the virus when the
birds are stressed. It has not been
known to be transmitted through eggs.
How is it diagnosed?
The best way to diagnose the disease is to send suspect
birds to the Minnesota Poultry Testing Laboratory or University of Minnesota Veterinary
Diagnostic Laboratory for a post-mortem examination. The diagnostician can
examine the trachea for clinical signs and run additional tests to confirm the
disease.
Is there a risk to people?
Infectious laryngotracheitis is not known to affect people.
Poultry meat and egg products are considered safe when proper cooking methods
are followed.
How can it be prevented?
The best method of prevention for ILT and other poultry
diseases is biosecurity. The virus can be inactivated with proper use of disinfectant
chemicals or heat. Birds returning from sales or exhibitions should be kept
separate from the rest of the flock for 30 days, should be cared for last when doing
chores, and should be closely observed for signs of disease.
Vaccines are also available to protect flocks that may be
exposed to the ILT virus. However, it is important to note, the virus from the
vaccine can remain dormant in vaccinated birds and those carrier birds have the
potential to spread infection to non-vaccinated birds. Once a producer begins
flock vaccination, annual vaccination needs to continue. Vaccines of Tissue
Culture Origin (TCO) and recombinant ILT vaccines are recommended over Chicken Embryo
Origin (CEO) vaccines, because the potential risk of virus spread from TCO vaccinated
birds is less. Vaccination is only recommended in places where ILT is endemic
or for flocks that may frequently come in contact with infected or previously
vaccinated birds such as at shows or exhibitions.
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