Gallid alphaherpesvirus 1 (GaHV-1) is a species of virus in the order Herpesvirales, family Herpesviridae, subfamily Alphaherpesvirinae, and genus Iltovirus.

[2][3] Originally recognised in chickens in the United States in 1926, this virus causes avian infectious laryngotracheitis (abbreviated as AILT, ILT, or LT), a potentially fatal, economically deleterious disease, widely recognised as one of the most contagious diseases in the poultry industry.

Both of these are in a separate genus to Gallid alphaherpesvirus 1; Mardivirus, which is united with Iltovirus under the same subfamily; Alphaherpesvirinae.

[4] Symptoms include coughing, sneezing, head shaking, lethargy, discharge from the eyes and nostrils (sometimes bloody), and difficulty breathing.

Biosecurity measures including quarantine, isolation, and disinfection are very important in controlling the spread of an outbreak.