• Cause: Gallid alphaherpesvirus 1 (GaHV-1), occurs mainly in chickens, but can be seen in pheasants, and peafowl.

ℹ️ A World Organisation for Animal Health/OIE listed disease.

• Signs: dyspnea.
• Diagnosis: PCR.
• Treatment: supportive.
• Prognosis: poor to good depending on severity of signs.

• Dyspnea.
• Egg production drop.
• Rales.
• Conjunctivitis.
• Swelling of the infraorbital sinuses.
• Serous ocular and nasal discharge.
• Purulent oculonasal discharge with secondary bacterial infection.

• Asphyxia.
• Death.

• Worldwide.

• Young or immunosuppressed birds are at greater risk.

• Production loss.
• Mortality loss.

• GaHV-1 is found within the family Herpesviridae.
• The virus has been shown to be antigenically homogeneous leading to good cross protection from vaccines.
• GaHV-1 is an enveloped, double stranded DNA virus.

Specific

• Unvaccinated birds.
• Immunosuppression.
• Cohabitation with turkeys, ducks or geese who may shed the virus but usually are asymptomatic.

• GaHV-1 has an affinity to the respiratory tract epithelium where it attaches by fusing its outer membrane with the cell plasma membrane.
• Infection occurs mainly in the larynx and upper trachea.
• Viral replication within the epithelial cells and their release by exocytosis leads to high level of cellular damage and concurrent hemorrhage.
• Intermittent viral shedding may occur up to 20 weeks post-infection.
• Latency is established in the trigeminal ganglia.

• Timecourse varies depending on viral dose and bird health status.
• Clinical signs appear between 5 and 14 days after exposure.
• Intermittent viral shedding may occur up to 20 weeks post-infection.

• ILTV transmits very quickly and easily horizontally by virus excreting birds.
• Bird-to-bird contact is necessary to maintain circulating virus within populations. However, fomites play a large role in transmission of the virus from infected flocks to naive birds.
• Contaminated equipment, workers, machinery and manure are all risks to spread.
• The spreading of non-composted manure from vaccinated or infected flocks can lead to epizootic outbreaks.
• Recovered birds will always be positively infected.

Refereed papers

• Recent references from PubMed and VetMedResource.

Other sources of information

• Lougue C M, Andreasen C B, Borst L B et al (2020) Other Bacterial Diseases. In: Diseases of Poultry. 14th edn. Eds: Swayne D E et al. pp 1010-1018.
• Lierz M & Heffels-Redmann U (2019) Respiratory Disorders. In: BSAVA Manual of Backyard Poultry Medicine and Surgery. Eds: Poland G & Raftery A. BSAVA, UK. pp 160-177.
• Raftery A & Jones R (2019) Reproductive and Laying Disorders. In: BSAVA Manual of Backyard Poultry Medicine and Surgery. Eds: Poland G & Raftery A. BSAVA, UK. pp 205-215.
• Williams D L (2019) Ophthalmological and Otic Disorders. In: BSAVA Manual of Backyard Poultry Medicine and Surgery. Eds: Poland G & Raftery A. BSAVA, UK. pp 150-159.
• Crespo R, Franca M S, Fenton H & Shivaprasad H L (2018) Galliformes and Columbiformes. In: Pathology of Wildlife and Zoo Animals. Eds: Terio K A, McAloose D & Leger J St. Academic Press, UK. pp 741-767.
• Roberts V (online) Chicken Health and Disease. VicVet. Website: www.vicvet.com.