Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data

M.E.H. Bos, R.M. van Boven, M. Nielen, A. Bouma, A.R.W. Elbers, G. Nodelijk, G. Koch, A. Stegeman, M.C.M. de Jong

Research output: Contribution to journalArticleAcademicpeer-review

44 Citations (Scopus)

Abstract

Despite continuing research efforts, knowledge of the transmission of the highly pathogenic avian influenza (HPAI) virus still has considerable gaps, which complicates epidemic control. The goal of this research was to develop a model to back-calculate the day HPAI virus is introduced into a flock, based on within-flock mortality data. The back-calculation method was based on a stochastic SEIR (susceptible (S) - latently infected (E) - infectious (I) - removed (= dead; R)) epidemic model. The latent and infectious period were assumed to be gamma distributed. Parameter values were based on experimental H7N7 within-flock transmission data. The model was used to estimate the day of virus introduction based on a defined within-flock mortality threshold (detection rule for determining AI). Our results indicate that approximately two weeks can elapse before a noticeable increase in mortality is observed after a single introduction into a flock. For example, it takes twelve (minimum 11 - maximum 15) days before AI is detected if the detection rule is fifty dead chickens on two consecutive days in a 10 000 chicken flock (current Dutch monitoring rule for notification). The results were robust for flock size and detection rule, but sensitive to the length of the latent and infectious periods. Furthermore, assuming multiple introductions on one day will result in a shorter estimated period between infection and detection. The implications of the model outcomes for detecting and tracing outbreaks of H7N7 HPAI virus are discussed.
Original languageEnglish
Pages (from-to)493-504
JournalVeterinary Research
Volume38
Issue number3
DOIs
Publication statusPublished - 2007

Fingerprint

H7N7 Subtype Influenza A Virus
Influenza in Birds
avian influenza
Poultry
Orthomyxoviridae
Influenza A virus
flocks
poultry
Mortality
Chickens
Research
Disease Outbreaks
Viruses
chickens
Infection
detection limit

Keywords

  • classical swine-fever
  • realistic distributions
  • infectious periods
  • epidemic models
  • transmission
  • netherlands
  • outbreaks
  • chickens
  • h5n1

Cite this

Bos, M.E.H. ; van Boven, R.M. ; Nielen, M. ; Bouma, A. ; Elbers, A.R.W. ; Nodelijk, G. ; Koch, G. ; Stegeman, A. ; de Jong, M.C.M. / Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data. In: Veterinary Research. 2007 ; Vol. 38, No. 3. pp. 493-504.
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Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data. / Bos, M.E.H.; van Boven, R.M.; Nielen, M.; Bouma, A.; Elbers, A.R.W.; Nodelijk, G.; Koch, G.; Stegeman, A.; de Jong, M.C.M.

In: Veterinary Research, Vol. 38, No. 3, 2007, p. 493-504.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Estimating the day of highly pathogenic avian influenza (H7N7) virus introduction into a poultry flock based on mortality data

AU - Bos, M.E.H.

AU - van Boven, R.M.

AU - Nielen, M.

AU - Bouma, A.

AU - Elbers, A.R.W.

AU - Nodelijk, G.

AU - Koch, G.

AU - Stegeman, A.

AU - de Jong, M.C.M.

PY - 2007

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AB - Despite continuing research efforts, knowledge of the transmission of the highly pathogenic avian influenza (HPAI) virus still has considerable gaps, which complicates epidemic control. The goal of this research was to develop a model to back-calculate the day HPAI virus is introduced into a flock, based on within-flock mortality data. The back-calculation method was based on a stochastic SEIR (susceptible (S) - latently infected (E) - infectious (I) - removed (= dead; R)) epidemic model. The latent and infectious period were assumed to be gamma distributed. Parameter values were based on experimental H7N7 within-flock transmission data. The model was used to estimate the day of virus introduction based on a defined within-flock mortality threshold (detection rule for determining AI). Our results indicate that approximately two weeks can elapse before a noticeable increase in mortality is observed after a single introduction into a flock. For example, it takes twelve (minimum 11 - maximum 15) days before AI is detected if the detection rule is fifty dead chickens on two consecutive days in a 10 000 chicken flock (current Dutch monitoring rule for notification). The results were robust for flock size and detection rule, but sensitive to the length of the latent and infectious periods. Furthermore, assuming multiple introductions on one day will result in a shorter estimated period between infection and detection. The implications of the model outcomes for detecting and tracing outbreaks of H7N7 HPAI virus are discussed.

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KW - realistic distributions

KW - infectious periods

KW - epidemic models

KW - transmission

KW - netherlands

KW - outbreaks

KW - chickens

KW - h5n1

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DO - 10.1051/vetres:2007008

M3 - Article

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SP - 493

EP - 504

JO - Veterinary Research

JF - Veterinary Research

SN - 0928-4249

IS - 3

ER -