A simple model for simulating immunity rate dynamics in a tropical free-range poultry population after avian influenza vaccination

In developing countries, vaccination against highly pathogenic avian influenza subtype H5N1 (HPAI) in free-range poultry flocks is usually implemented as periodic campaigns and newborn chicks are generally not vaccinated by farmers between vaccination passes. The demographic population turnover leads to a continuous decrease in the population immunity rate (PIR) over time. We present a simple Leslie matrix model for estimating population turnover and PIR dynamics in a hypothetical small-size vaccinated free-range poultry population. Four different vaccination scenarios were identified assuming necessary procedures to achieve immunity. The results indicate that high levels of population immunity are difficult to sustain. Assuming an animal immunity response of 80% after vaccination and a constant population size, PIR 4 months after vaccination was 30% in all the scenarios. Predictions averaged over time showed mean PIR between 36% and 48%, which is below the population immunity thresholds for eradication approximated from R0 estimates.

Bibliographic Details

Main Authors:	Lesnoff, Matthieu, Peyre, M., Duarte, P.C., Renard, J.F., Mariner, Jeffrey C.
Format:	Journal Article biblioteca
Language:	English
Published:	Cambridge University Press 2009-10
Subjects:	poultry, free range husbandry, avian influenza virus, immunity,
Online Access:	https://hdl.handle.net/10568/37 https://doi.org/10.1017/S0950268809002453
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