Montoring in the Vaccination Zone

Monitoring Efficacy of Vaccination

• HI test one month after the second vaccination. 
• 20 serum samples per flock.
• HI titre greater than 1:16 in more than 70% of tested samples to prove that vaccination is effective (Guidelines set by Agriculture, Fisheries and Conservation Department, Hong Kong).

Monitoring for Avian Influenza Infection in Vaccinated Poultry Flocks

Sentinel Birds
The use of sentinel birds is the most practical method for monitoring a vaccinated flock. It is widely used.

• Thirty to sixty clearly identified unvaccinated sentinel birds must be placed in each house.
• Ten to twenty serum samples collected from sentinels must be tested every 30 – 45 days (ELISA or HI).
• If the sentinels seroconvert the flock is considered avian influenza positive and must be culled.

Serology

Detection of avian influenza infection using the N sub-type
Serology can be used to trace infected birds in a vaccinated flock if a heterologous vaccine is used. The vaccine strain in a heterologous vaccine contains the same H sub-type as the field strain but a different N sub-type. Vaccinated and infected birds can be differentiated based on the serological response to the N group. For more information see Vaccines.

• Birds infected with avian influenza develop antibodies to the field strain N sub-type
  
• Birds vaccinated against avian influenza have antibodies to the vaccine strain N sub-type. Vaccinated birds that are also infected will develop antibodies to the field strain and vaccine strain N proteins.
  
• N-antibody detection tests can be used as routine tests for differentiating between vaccinated and infected birds
  
  For more information see:
• Ilaria Capua, Calogero Terregino, Giovanni Cattoli, Franco Mutinelli and J.F Rodriguez
  Development of a DIVA (Differentiating Infected from Vaccinated Animals) strategy using a vaccine containing a heterologous neuraminidase for the control of avian influenza.
  Avian Pathology (2002) 32, 47-55
  Abstract