Vaccine reactions in poultry flocks

Disease causing organisms are ubiquitous in poultry producing facilities all around the world. Vaccination is one of the tools in the arsenal that is frequently used. Vaccination does not provide a 100% guarantee that a disease will be prevented from causing losses. In most situations, vaccination serves as a means to reduce/minimize the economic impacts of certain diseases.

 

Following the administration of a live vaccine in poultry, the vaccine virus must infect target cells and replicate to increase their numbers in order to stimulate the immune system. If the vaccine is administered properly to healthy birds, a “normal” vaccine reaction will occur although this normal reaction can vary considerably among flocks.

 

A good basic rule is that a mild respiratory reaction should be detected at 2 to 3 days following vaccine administration and should last for 5 to 7 days. The clinical reaction in the birds will include respiratory noise (snicking), head shaking and watery eyes. These reactions should be self-limiting. If no reaction is detected, it is likely that little or no stimulation of the immune system has occurred. In this case, the birds are still susceptible to field disease challenge. If the reaction is more severe  than desired or it is not self-limiting, this is cause for concern and should be investigated.

 

It is often reported in the commercial poultry industry that chickens routinely need to be treated with antibiotics following vaccination to “buffer” the reactions and to control secondary E.coli septicemia and airsaculitis.

 

Many of these flocks finish with poor body weights, poor uniformities, high feed conversions and some even experience increased mortality due to the severe or prolonged vaccine reactions.

 

Chick quality, uniformity of maternal antibody, vaccine strain, vaccine administration, health status of flock (presence of immunosuppressive conditions, Mycoplasma gallisepticum infection, etc) and poultry house management are among the most common factors that can play an important role in the severity of vaccine reactions  especially when respiratory disease vaccines are administered.

Simply living with excessive vaccine reactions and the associated losses is totally unacceptable in today’s highly competitive industry. Some operations experience this problem more than others.

How often do you encounter with this problem in your farm?

Do you think that treating affected flocks with antibiotics is the best available solution to cope with this problem?

Are you one of those people who always blame vaccine quality as the main cause of these reactions?

What are your suggestions to reduce/minimize the occurrence of these reactions?