What is infectious laryngotracheitis?

board of animal health

Reportable Disease of the Month

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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