Infectious laryngotracheitis occurs in chickens of all ages in most countries. Laryngotracheitis virus is a cuboidal, enveloped DNA herpes virus.
- Causes of Infectious laryngotracheitis >
- Effects of Infectious laryngotracheitis >
- Diagnosis of Infectious laryngotracheitis >
- Treatment & Control of Infectious laryngotracheitis >
Causes of Infectious laryngotracheitis
ILT is mainly acute to chronic and affects all birds, though usually those older than 4 weeks. The herpes virus is a cuboidal, enveloped DNA virus.
Mode of transmission
Older carrier birds are a common source of infection. Aerosol, fomites, ingestion of contaminated litter are also common means for viral spread.
Effects of Infectious laryngotracheitis
An incubation period of 6-12 days. There are many pathotypes of the virus. Some are very mild and others can cause severe morbidity and mortality.
Mortality (average 10-20%, range 5-70%), morbidity (90-100%), drop in egg production (10-20%), watery eyes early on, then nasal discharge, gasping, tracheal rales and stretching necks are common sings. Slinging of blood from nose causes blood stains along the sides of walls.
Most birds recover in 10-14 days if infection is not complicated by immunosuppression or a secondary bacterial or mycoplasma infection.
Postmortem lesions
Mucous in trachea is seen first, followed later by necrotic tissue, then blood. Inflammation of bronchi and lungs, foamy air sacs, oedema and congestion of the conjuctive and infraorbital sinuses are commonly seen.
Diagnosis of Infectious laryngotracheitis
Laboratory tests include microscopic observation of intranuclear inclusion bodies in the lesions (usually trachea).
Blood in the trachea is a important lesion.
Treatment & Control of Infectious laryngotracheitis
Prevention
Vaccinate chickens with live attenuated product by-water (embryo-drived), spray or eyedrop (cell culture derived) at 2-4 weeks of age only in endemic areas. Broilers are rarely vaccinated for ILT.
Revaccination of pullets at 10-14 weeks by eyedrop. Revaccinate force moulted hens.
Treatment
Antibiotics for secondary invaders are helpful. Vaccinate only in endemic areas and quarantine all affected flocks.
