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

chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...

s 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 Poultry farming is the form of animal husbandry which raises domesticated birds such as chickens, ducks, turkeys and geese to produce meat or eggs for food. Poultry – mostly chickens – are farmed in great numbers. More than 60 billion chicke ...

. The virus and its associated disease also occur in pheasants.

Taxonomy

''Gallid alphaherpesvirus 1'' is classified in the genus ''Iltovirus''. The only other species in this genus, and therefore its closest known relative, is ''

Psittacid alphaherpesvirus 1 Pacheco's disease is a highly infectious and acute bird disease caused by a species of herpesvirus, ''Psittacid alphaherpesvirus 1'' (PsHV-1). All psittacine species are susceptible to Pacheco's disease, mainly those in zoological collections and ...

'', which affects parrots. There are two other herpesviruses that affect chickens: ''

Gallid alphaherpesvirus 2 Marek's disease is a highly contagious viral neoplastic disease in chickens. It is named after József Marek, a Hungarian veterinarian who described it in 1907. Marek's disease is caused by an alphaherpesvirus known as "Marek's disease virus" ( ...

'' (cause of Marek's disease) and ''

Gallid alphaherpesvirus 3 ''Gallid alphaherpesvirus 3'' (GaHV-3) is a species of virus in the genus ''Mardivirus'', subfamily ''Alphaherpesvirinae'', family ''Herpesviridae'', and order ''Herpesvirales The ''Herpesvirales'' is an order of dsDNA viruses (Baltimore group ...

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

Pathology

Transmission

GaHV-1 is shed in respiratory secretions and transmitted by droplet inhalation or via fomites. A previously unexposed flock will develop cases for two to eight weeks following introduction. The incubation period is two to eight days.

Clinical signs and diagnosis

Symptoms include coughing, sneezing, head shaking, lethargy, discharge from the eyes and nostrils (sometimes bloody), and difficulty breathing. The name comes from the severe inflammation of the

larynx The larynx (), commonly called the voice box, is an organ in the top of the neck involved in breathing, producing sound and protecting the trachea against food aspiration. The opening of larynx into pharynx known as the laryngeal inlet is about ...

and

trachea The trachea, also known as the windpipe, is a Cartilage, cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air-breathing animals with lungs. The trachea extends ...

. A diphtheritic membrane may form in the trachea, causing obstruction. There may be problems in egg laying and the production of abnormal or thin-shelled eggs. Mortality is typically less than 15 percent.

Histopathology Histopathology (compound of three Greek words: ''histos'' "tissue", πάθος ''pathos'' "suffering", and -λογία '' -logia'' "study of") refers to the microscopic examination of tissue in order to study the manifestations of disease. Spe ...

, PCR,

ELISA The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence ...

immunofluorescent Immunofluorescence is a technique used for light microscopy with a fluorescence microscope and is used primarily on microbiological samples. This technique uses the specificity of antibodies to their antigen to target fluorescent dyes to specifi ...

staining, and viral isolation are all possible methods of diagnosis.

Treatment and control

A vaccine is available ( ATCvet code: ), but it is susceptible to undesired recombination and it does not prevent latent infections. It can be used during an outbreak to decrease morbidity and deaths. A confirmed case will usually result in the establishment of a

quarantine A quarantine is a restriction on the movement of people, animals and goods which is intended to prevent the spread of disease or pests. It is often used in connection to disease and illness, preventing the movement of those who may have been ...

zone around the farm. Inside this quarantine zone, poultry workers will avoid poultry farms to prevent the spread of the virus.

Biosecurity Biosecurity refers to measures aimed at preventing the introduction and/or spread of harmful organisms (e.g. viruses, bacteria, etc.) to animals and plants in order to minimize the risk of transmission of infectious disease. In agriculture, thes ...

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

References

External links

Avian infectious laryngotracheitis
expert reviewed and published by

WikiVet WikiVet is a wiki of veterinary content based on the MediaWiki platform. The website is a collaborative initiative between various veterinary schools, and its content covers the entire veterinary curriculum. WikiVet is part of the WikiVet Educatio ...

, accessed 07/10/2011
Virus Pathogen Database and Analysis Resource (ViPR): ''Herpesviridae''
{{DEFAULTSORT:Gallid alphaherpesvirus 1 Alphaherpesvirinae Bird diseases Poultry diseases Animal viral diseases