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Western Small Flocks Collaborative

Infectious Laryngotracheitis (ILT)

Learn how ILT spreads, the signs to watch for, and steps you can take to protect your birds.

ILT Factsheet
Silhouette icon of a Infectious Laryngotracheitis virus infected chicken

Quick Facts

Silhouette icon of a Infectious Bronchitis virus shape ILT disease is caused by a herpesvirus
Silhouette icon of a dark brown dead chicken Spreads quickly, and can cause high mortality in chicken flocks
Silhouette of pheasant Gamebirds and peafowl can be infected, but rare in turkeys
Silhouette icon of a dark brown human figure Does not spread to or infect humans
Silhouette of a boot with dirt on the sole and top Spreads through infected birds, contaminated surfaces, and coughing or nasal discharge

What is ILT?

Infectious Laryngotracheitis (ILT) is a serious and highly contagious respiratory disease caused by a herpesvirus. It primarily affects chickens, but pheasants and peafowl are also susceptible. The virus spreads through respiratory droplets, direct contact between birds, and contaminated equipment or clothing. Symptoms can include watery eyes, coughing, gasping for air, and sudden death. Birds that are infected, recovered, or vaccinated may carry and shed the virus without showing signs, and the virus can reactivate during periods of stress. There is no cure for ILT. Prevention through strong biosecurity and management practices is the most effective defense.

Silhouette icon of a brown caution symbol with an exclamation point in the center There is no cure and infected birds may die or become life-long carriers and continue to shed the virus.
Bird affected with ILT showing signs of infraorbital sinus swelling and conjunctivitis.
Bird affected with ILT showing signs of infraorbital sinus swelling and conjunctivitis.
Oral cavity of a chicken affected by ILT, showing raised white plaques on the mucosal surfaces.
Oral cavity of a chicken affected by ILT, showing raised white plaques on the mucosal surfaces.

Signs of ILT

ILT is a viral respiratory disease that can look very similar to other poultry respiratory problems. Because symptoms overlap with conditions like infectious bronchitis, avian influenza, and Newcastle disease, testing is the only way to confirm ILT.

What to watch for in your flock:

  • Respiratory distress: Coughing, gasping, rattling sounds, or birds stretching their necks to breathe.
  • Discharge: Watery eyes, swollen sinuses, or nasal discharge.
  • Oral and throat lesions: White plaques or caseous material in the mouth, larynx, and trachea.
  • Reduced production: Drop in egg laying, poor growth, or reduced feed intake.
  • Sudden death: Some birds die quickly without showing obvious signs beforehand.

Course of disease:

  • Birds that survive may remain carriers of the virus and shed it during times of stress.
  • Outbreaks often spread rapidly through a flock, especially if birds are housed closely together.
  • Mortality rates vary widely, from low levels in mild cases to over 70% in severe outbreaks.
Common signs of ILT in chickens include swollen or watery eyes, nasal discharge that may be bloody, coughing or wheezing, gasping for air with an extended neck, and lesions in the mouth or throat. Birds may also show reduced feed and water intake, a drop in egg production, and increased mortality within the flock.

How does ILT Spread?

Contact with infected birds:

  • Carrier birds may look healthy but still shed the virus.
  • Sick birds spread ILT in saliva, nasal discharge, eye secretions, and respiratory droplets.

Contact with contaminated surfaces:

  • Virus survives on shared tools, boots, clothing, feeders, or bedding.
  • People can move the virus between flocks on their hands, boots, or clothing.
  • Dust and dander from infected houses can carry the virus short distances in the air.
Common ways ILT spreads between birds, people, and equipment

How Do You Treat ILT?

There is no cure for ILT. Birds that have recovered from or were vaccinated for ILT may carry and spread the virus.

How Do You Prevent ILT?

Practice Biosecurity

  • Limit contact with birds from other flocks.
  • Wear coop-dedicated shoes to keep out germs.
  • Keep the coop, equipment, and your hands clean.

Separate New or Returning Birds

  • Isolate new or returning birds for at least 3 weeks and monitor for signs of illness.
  • Germs can spread before birds show signs.
  • Birds that have recovered from or were vaccinated for ILT may carry and spread the virus.

Limit Visitors and Shared Tools

  • Require approved visitors to wear clean clothes and boot covers.
  • Minimize sharing tool or equipment.

Handle Healthy Birds First

  • Care for birds in this order: young → adults → sick, to avoid spreading germs.
  • Wash or sanitize hands and equipment between different bird groups.

What if ILT is Found in Your Flock?

Work with a Veterinarian

  • ILT is reportable in some states.
  • Your veterinarian can help confirm the disease and guide next steps.

Isolate Sick Birds

  • Separate sick birds from the flock to limit spread of the virus.

Don’t Spread Disease

  • Do not buy or sell birds during or after an outbreak.
  • Even healthy-looking birds can shed this virus.

Confirm with Testing

  • Testing can identify the cause of illness and help guide your next steps.
  • Work with your veterinarian to coordinate testing.

Plan Long-Term Management

  • Infected birds remain carriers, so some flocks may choose to depopulate their flock.
  • If ILT is reportable in your state, there may be additional management requirements.