Infectious Laryngotracheitis

Infectious Laryngotracheitis, also known as ILT, is an infectious viral infection caused by Gallid Herpesvirus 1, a herpes virus with a double-stranded DNA of the genus Alphaherpesvirinae.

This viral disease, like most of them, also has to be reported.


The ILT is transmitted by direct and indirect animal contact.

In direct animal contact, the pathogen is excreted in droplet form through the respiratory tract and passed on to the next chicken. An animal carrying the pathogen does not always have to show obvious symptoms.

Indirect transmission can occur through egg cartons, cages or feeding equipment, but not through the eggs themselves.

The incubation period is between 4 and 12 days and can lead to a mortality rate of up to 70% in serious cases. However, such mortality is rather rare and usually between 5 and 10%.

The most common ILT infections are recorded in the autumn/winter months. If a chicken is infected with infectious laryngotrachheitis and survives this disease, it will remain latently infected for a lifetime.


ILT can be divided into an acute and a less acute form, depending on the type of herpes virus. The subacute form of ILT has the same symptoms as the severe infection, but less pronounced. Inflammation of the upper airways and the larynx is generally considered characteristic. This can lead to death by suffocation of the excessively formed mucus in an acute form of infectious laryngotracheitis.

Visible symptoms:

  • Reduced laying performance
  • Sniffles
  • Swelling of the face
  • Difficult breathing (beak breathing)
  • Rattle/Panting
  • Trachoma
  • Nasal discharge or coughing up bloody mucus

Patological symptoms:

  • Congestion and hyperemia of the larynx and trachea
  • In case of heavy flow also cheesy coatings or pseusomembranes

If the suspicion of infection by ILT is present, it can be confirmed or ruled out by an electro-microscopic examination of a tracheal swab or by detection of antibodies by immunofluorescence.

In the meantime, rapid but somewhat more expensive PCR detection is also possible.


Treatment of infectious laryngotracheitis is not yet possible either. Only inoculation, administered by eye drops or via drinking water, can guarantee protection against ILT. Even after the outbreak of the disease, it is often still possible to minimize the spread by subsequently vaccinating chickens that are not yet infected.


As with any disease described so far, the ILT can only point out once again that hygiene is the key to avoiding diseases at all times. This also includes taking care not to add diseased chickens to the herd.

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