Gallid Herpesvirus 1
| Gallid Herpesvirus 1 | |
|---|---|
| Class | DNA Viruses |
| Order | Caudovirales |
| Family | Herpesviridae |
| Genus | Infectious Laryngotracheitis-like Viruses |
| Species | GHV-1 |
Also Known As — Infectious laryngotracheitis — ILT — Avian Infectious Laryngotracheitis — AILT
Caused By — Gallid Herpesvirus I — GHV-1 — Infectious Laryngotracheitis Virus — ILTV — LTV
Introduction
Gallid Herpes virus causes respiratory disease in chickens and pheasants.
This disease is notifiable to the World Organisation for Animal Health (OIE)
Disease varies from mild to peracute, with mortality in peracute outbreaks exceeding 50%.
As with all herpesviruses, GHV-1 can remain latent in carriers after infection and then be shed intermittently, recrudescing with stress.
Signalment
Only chickens, pheasants and peafowl are naturally infected.
Distribution
Transmission is via direct contact and contaminated people and equipment. Vermin and wild bords and dogs may aid mechanical transmission.
Clinical Signs
Respiratory signs – Nasal discharge which is often bloody, Coughing which may include blood, Sneezing, Dyspnoea, Gasping, Upper respiratory tract pain, Abnormal lung sounds.
Decreased egg production, Thin egg shells, Lack of growth
Neurological and ophthalmologic signs may develop
Death may occur rapidly and with high mortality in peracute and acute disease, or in subacute cases respiratory signs may be present for several days before death and more birds will recover.
Diagnosis
On post-mortem, haemorrhagic tracheitis and bloodstained mucus are evident. Pneumonia and sacculitis may also be seen. Caseous diptheritic membranes may be present on the mucosae of the upper respiratory tract.
Histopathology reveals loss of cilia, mucosal gland atrophy, intranuclear inclusion bodies and epithelial cell sloughing. Characteristic syncytia develop. A fibrinonecrotic membrane may develop in more chronic disease cases.
Antigen ELISA is both straightforward, quick and sensitive.
Immunofluorescent or Immunoperoxidase staining can also be performed and is more rapid but less sensitive.
Virus isolation can be performed on a variety pf tissues including tracheal swabs or tissue samples.
Agar Gel Immunodiffusion can detect virus in tracheal samples.
Electron microscopy can be used to demonstrate viral particles in tracheal scrapings or exudates but is insensitive.
Measuring viral antibody measures infection indirectly as serum anibodies peak around 2 weeks after infection and wane slowly afterwards.
Treatment
Where early diagnosis is made, vaccination can be administered in the face of infection to help reduce further morbidity and mortality.
Control
ILT can be effectively controlled by vaccination. Vaccinated and unvaccinated birds should not be mixed due to the possibility of reversion to virulence. Most are modified live isolates and are administered by eye drop.
Adequate biosecuriy, quarantine and disinfection is also essential.
Wild birds and vermin should be prevented from accessing poultry and their food/water sources.
| Gallid Herpesvirus 1 Learning Resources | |
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Gallid Herpesvirus 1 Flashcards |
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GHV Publications |
References
Animal Health & Production Compendium, Gallid Herpesvirus datasheet, accessed 05/06/2011 @ http://www.cabi.org/ahpc/