Modelling the effects of isolation, culling, and vaccination of domestic birds during an outbreak of A(H5N6) in the Philippines with half-saturated incidence

Date of Publication


Document Type

Master's Thesis

Degree Name

Master of Science in Mathematics

Subject Categories

Immunology and Infectious Disease | Poultry or Avian Science


College of Science


Mathematics and Statistics Department


Highly Pathogenic Avian Influenza (HPAI) A(H5N6) is a mutated virus of A(H5N1) and a new emerging infection which recently caused an outbreak in the Philippines. This A(H5N6) outbreak resulted to depopulation of 667,184 domestic birds. In a recent study, proposed mathematical models for A(H5N6) in the Philippines acknowledged three control strategies: personal protection for humans, isolation of infected poultry, and vaccination of susceptible birds. A number of authors also stress that applying half-saturated incidence (HSI) in modelling infectious diseases is more realistic compared to bilinear incidence. In this study, we incorporate HSI in our mathematical models and investigate three intervention strategies against A(H5N6). For the application of isolation and treatment of infected birds in our model, we emphasize that not all birds released from confinement have fully recovered. In administering preventive vaccine to poultry, we add a waning rate for vaccine to recognize that vaccines effectiveness weakens over time. While for the modified culling of infected and susceptible birds that are high-risk to infection, we employ HSI into the culling rate. After computing for the basic reproduction number R0, we determine the direction of bifurcation when R0 < 1. All the four mathematical models presented in this paper exhibit forward bifurcation. We simulate the models and compare the consequences of utilizing different intervention strategies in the poultry population. Despite the challenges of applying each control strategy, we have shown that culling infected birds at least once a week ( 1 7 per day) together with culling of susceptible birds at most once every 60 days ( 1 60 per day) outperformed isolation and vaccination strategies in controlling an outbreak of A(H5N6).

Abstract Format






Accession Number


Shelf Location

Archives, The Learning Commons, 12F Henry Sy Sr. Hall

Physical Description

1 computer disc, 4 3/4 in.


Avian influenza A virus--Philippines; Mathematical models; Epidemics--Philippines; Infection; Communicable diseases; Avian influenza A virus--Vaccination

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