Laryngotracheitis infection

FACTS OF INFECTIOUS LARYNGOTRACHEITIS (LT) IN CHICKENS

  • It’s a highly infectious disease of worldwide distribution.
  • It induces significant economic losses due to high morbidity and variable mortality, drop in egg production, weight loss and susceptibility to other respiratory infections.
  • The disease is caused by a Herpes viral infection characterized by latency, persistency and reversion to virulence.
  • The viral infection induces chronic carrier for life, allowing the transmission to other birds and environmental contamination.

THE DIAGNOSIS CAN BE DONE BY

  • Clinical signs (Figure 1)
  • Post-mortem lesions: they may vary from mild to severe (Figure 2)
  • Histopathology: observations of typical giant cells and intranuclear inclusion bodies in the tracheal epithelium in the early stage of infection
  • Virus isolation
  • Molecular biology methods to detect viral DNA such as PCR
  • Serology
  • Other diagnostic methods such as immunohistochemistry and immunofluorescence
Suffocation produced in LT

Figure 1: suffocation

Severe laringotracheitis

Figure 2: severe laringotracheitis

CURRENT LIVE LT (CEO: CHICKEN EMBRYO ORIGIN OR TCO: TISSUE CULTURE ORIGIN) VACCINES SITUATION

These vaccines are able to provide protection but conversely, they have many side effects (Bagust 1986 and 1995, Graham 2000):

  • Latent and persistent LT virus infection = chronic carrier state in vaccinated birds
  • Reversion to virulence
  • Transmission to other birds
  • Shed into the environment
  • Induce vaccine reactions that affect growth performance

There is a need for a new protective and safe LT vaccine without the limitations of the conventional live vaccines.
It is the reason why Ceva, a leader in poultry vaccines, has developed a new approach to LT vaccination with a vectored vaccine: Vectormune® FP LT.