Infectious Laryngotracheitis (ILT) in Poultry

[ Signs of the disease | Spread of the disease | Disease prevention and control | Your responsibilities ]

Revised October 2001 Agdex 663-36 - Also available in PDF format - 172 KB

Infectious Laryngotracheitis (ILT) is a viral infection of the respiratory tract (trachea - windpipe) of chickens, pheasants and peafowl. It can spread rapidly among birds and causes high death losses in poultry that are susceptible. The disease is not a human health risk. Turkeys, ducks and geese do not get the infection but could spread the virus.

Signs of the disease

Infected birds will be coughing and gasping, will have difficulty breathing or may simply be found dead. There may be bloody exudate from the nose and mouth. Birds may stand with wings spread, head and neck extended and be struggling for air. Some birds show milder signs, with discharge from the eyes and nose. Up to 100 per cent of a flock can be affected, and up to 30 per cent may die.

Birds that recover may be carriers of the virus. They will appear healthy, but can be an ongoing source of virus to infect other birds. Birds that are stressed by transportation or other changes in their environment are more likely to develop the disease or begin shedding the virus. The carrier state can persist for up to two years. Farms may remain contaminated for long periods after outbreaks.

Spread of the disease

ILT is most readily spread by direct contact between susceptible birds and infected ones (Figure 1). It may be spread by contaminated equipment and vehicles or be carried into poultry houses on footware or clothing. Humans are the primary culprit in the spread of infection between farms.

Figure 1. Virus can spread between birds

The disease is rare in commercial poultry operations in Alberta. Surveillance is ongoing to detect it, and it is typically found in fancy or hobby flocks. These flocks may be introducing new birds to the flock on an ongoing basis and may not have the isolation that many commercial operations have. Some exotic species such as pheasants and quail can also carry the virus and spread it within mixed fancy flocks.

Disease prevention and control

Biosecurity is essential to control diseases such as ILT. The essential elements of biosecurity include the following:

Do not allow other people to enter your barns. This element is critical if these people are in contact with other poultry, especially fancy or hobby flocks.
If people must enter your barns, they should use boots and coveralls that you provide or be able to assure you that they have not been on another poultry farm that day.
Use a boot dip to help control disease, and change the dip frequently (daily).
Do not visit other poultry operations unless necessary. Wash and disinfect your boots and clothing before using them in your own barns after you return.
Limit vehicle traffic on your farm site to reduce the chances for contamination that you may track into your barns.
Do not allow animals access to your barns.
Store all dead carcasses in a closed container to prevent scavengers from dragging them around and spreading viruses or bacteria.
Do not have fancy birds and commercial poultry on the same farm. Employees of commercial farms should not have fancy flocks on their own farms.
Perform thorough cleanout and disinfection between flocks. The ILT virus can survive for a long time in a carcass, especially if the carcass is frozen. The virus dies quickly when exposed to sunlight or disinfectants.

Your responsibilities

If you suspect a problem with ILT or any other infectious disease, please submit sick or dead birds to a diagnostic laboratory for examination. The disease can only be confirmed by post mortem examination.

The ILT policy in Alberta specifies that Alberta Agriculture, Food and Rural Development will notify all commercial poultry operations within a 20 km radius of a farm where ILT has been diagnosed. This notice serves as a warning to producers to be aware of the disease, to enhance the biosecurity of their flocks and to submit any suspicious cases to the diagnostic laboratory for examination.

Figure 2. Producers should watch their poultry

If you have had ILT diagnosed on your farm, you will receive advice on control measures. In some instances, you may control the infection with vaccination. Treatment with antibiotics is not effective because this is a viral infection, but early vaccination can control death losses. This approach can be helpful in layer flocks if the disease occurs when there is still production potential. In other cases, slaughter is the best solution.

You must not sell birds without advising the buyer that ILT has been diagnosed on the farm. If you have vaccinated your flock, you should advise anyone you sell birds to because the vaccine virus can spread among birds.

Infectious Laryngotracheitis

Printable PDF version (2 pages)

Infectious Laryngotracheitis (ILT) is a respiratory disease caused by a herpesvirus. All chickens are susceptible to ILT. The natural entry route of the virus is through the respiratory tract and the eye of the chicken. The disease is extremely contagious and may be spread easily by contaminated equipment, people, litter, and other fomites (things that can carry the disease).

The signs of severe ILT include marked respiratory distress, expectoration of blood, high morbidity, and higher than normal mortality. It is important to remember that although not all ILT infections are this severe, they all are easily spread. ILT may be present in some chickens as a latent infection or as a weak pathogenic infection.

Naturally infected chickens and vaccinated chickens may become carriers and shed the ILT virus for long periods. As with other herpesviruses, stressful situations may cause latent infections to become active, causing carriers to spread the virus to other susceptible chickens.

Chickens with the weak pathogenic form of ILT infections may have signs that are barely distinguishable from other respiratory problems such as vaccine reactions, respiratory irritation caused by excessive ammonia or dust, infectious bronchitis virus, Newcastle disease virus, or mycoplasmosis. The only clinical signs may be ocular and nasal discharge, conjunctivitis, swollen infraorbital sinuses, or a decrease in egg production in hens.

Because ILT may cause only a mild infection in some chickens, it is important to treat all undiagnosed respiratory cases as potential ILT infections. Use good biosecurity practices within your company to do this successfully.

The signs and lesions of the weak pathogenic form of infection may not be distinctive enough to make a presumptive diagnosis of ILT. However, it can usually be confirmed in a relatively short time by proper diagnostic techniques. Collect samples from chickens that appear to be in the early stages of the disease to ensure the most accurate diagnosis.

ILT can be complicated by secondary bacterial infections, which may increase condemnation in your plant. Treatment of these secondary infections may also increase costs.

Remember that one of the best ways to control the spread of ILT is through early detection. Ensure that your company�s personnel can recognize the difference between normal and abnormal chickens and that they know what to do if they suspect ILT. The incubation period of ILT is 6-12 days; therefore, vaccination before an outbreak is feasible if ILT is recognized in time.

A Focus Program of the Mississippi State University Extension Service

By Sue Ann Hubbard, D.V.M., Poultry Specialist, College of Veterinary Medicine, and Fred Lehman, D.V.M., Extension Veterinarian

Information Sheet 1623
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. Ronald A. Brown, Director

(500-6-01)

This document may be copied and distributed for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service

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