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Laryngotracheitis (L.T.) Surfaces Twice

Livestock Update, February 1997

Phillip J. Clauer, Poultry Extension Specialist

A case of Laryngotracheitis (L. T.) surfaced after both the Virginia State Fair and after the Fall Show of the Virginia Poultry Breeders Association. Fortunately for the U.S. poultry industry, both seem to have been a vaccine roll-over or vaccine related break. In both cases, birds were purchased at the shows and taken home to an adult flock. The purchased birds seemed healthy and never got ill. However, all the birds in the flock of the purchaser got sick and died or were voluntarily destroyed.

This should alert everyone on three important biosecurity points.

  1. All those who vaccinated for LT were protected from this potential disease break. Those who had non-vaccinated birds at home got LT.

  2. Only use the tissue or cell culture type vaccine to vaccinate show or exhibition birds. The chick embryo type vaccines can easily spread from vaccinated birds to susceptible birds especially during the first 4 to 6 weeks after vaccination. The live chick embryo type vaccine also has been shown to produce carrier birds which when placed under stress can shed this vaccine virus periodically for years.

  3. Bringing adult birds back to your established flock can be extremely dangerous from a disease standpoint. In both cases the L.T. infected birds were purchased at the Richmond State Fair grounds during a show. In both cases the infected birds survived. However, all the birds in the established flocks became sick with L.T. All birds in the established flocks died or were voluntarily destroyed.

The best way to bring new birds into an established flock is by bringing in hatching eggs or day old chicks. Adult birds can carry many poultry diseases without showing symptoms of disease. This past year I am aware of laryngo, coryza scaly leg mites and other parasites (internal and external) being introduced to healthy established flocks because someone purchased and introduced adult stock to their flock from an outside source.

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