Effects of abundance on infection in natural populations: field voles and cowpox virus

Michael Begon, Sandra Telfer, Sarah Burthe, Xavier Lambin, Steve Patterson

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Detailed results on the dynamics of cowpox virus infection in four natural populations of the field vole, Microtus agrestis, are presented. Populations were sampled every 4 weeks (8 weeks in mid-winter) for 6 years. The purpose was to examine the relationships between overall or susceptible host abundance (N, S)
and both the number of infected hosts (I) and the prevalence of infection (I/N). Overall, both I and I/N increased with N. However, evidence for a threshold abundance, below which infection was not found, was at best equivocal in spite of the wide range of abundances sampled. Cross-correlation analyses reflected
annual and multi-annual cycles in N, I, S and I/N, but whereas N was most strongly correlated with contemporary values of I and I/N, in the case of S, the strongest correlations were with values 1 to 2 months preceding the values of I and I/N. There was no evidence for a ‘juvenile dilution effect’ (prevalence decreasing with abundance as new susceptibles flush into the population) and only weak evidence of a time-delayed effect of abundance on the number infected. We argue that these effects may occur only in systems with
characteristics that are not found here. Transfer function analyses, which have been neglected in epidemiology, were applied. These models, with ln(S) as the input parameter, in spite of their simplicity, could be linked closely to conventional formulations of the transmission process and were highly effective in
predicting the number infected. By contrast, transfer function models with ln(N) as the input parameter were less successful in predicting the number infected and/or were more complex and more difficult to interpret. Nonetheless, overall, we contend that while monitoring numbers susceptible has most to offer, monitoring overall abundance may provide valuable insights into the dynamics of infection.
Original languageEnglish
Pages (from-to)35-46
Number of pages12
JournalEpidemics
Volume1
Issue number1
Early online date6 Nov 2008
DOIs
Publication statusPublished - Mar 2009

Fingerprint

Cowpox virus
Arvicolinae
Infection
Population
Virus Diseases
Epidemiology

Keywords

  • transmission
  • wildlife
  • dynamics
  • transfer function
  • zoonoses

Cite this

Effects of abundance on infection in natural populations : field voles and cowpox virus. / Begon, Michael; Telfer, Sandra; Burthe, Sarah; Lambin, Xavier; Patterson, Steve.

In: Epidemics, Vol. 1, No. 1, 03.2009, p. 35-46.

Research output: Contribution to journalArticle

Begon, Michael ; Telfer, Sandra ; Burthe, Sarah ; Lambin, Xavier ; Patterson, Steve. / Effects of abundance on infection in natural populations : field voles and cowpox virus. In: Epidemics. 2009 ; Vol. 1, No. 1. pp. 35-46.
@article{cdd5d46bf4f04d5ca76f37b905026c8a,
title = "Effects of abundance on infection in natural populations: field voles and cowpox virus",
abstract = "Detailed results on the dynamics of cowpox virus infection in four natural populations of the field vole, Microtus agrestis, are presented. Populations were sampled every 4 weeks (8 weeks in mid-winter) for 6 years. The purpose was to examine the relationships between overall or susceptible host abundance (N, S) and both the number of infected hosts (I) and the prevalence of infection (I/N). Overall, both I and I/N increased with N. However, evidence for a threshold abundance, below which infection was not found, was at best equivocal in spite of the wide range of abundances sampled. Cross-correlation analyses reflected annual and multi-annual cycles in N, I, S and I/N, but whereas N was most strongly correlated with contemporary values of I and I/N, in the case of S, the strongest correlations were with values 1 to 2 months preceding the values of I and I/N. There was no evidence for a ‘juvenile dilution effect’ (prevalence decreasing with abundance as new susceptibles flush into the population) and only weak evidence of a time-delayed effect of abundance on the number infected. We argue that these effects may occur only in systems with characteristics that are not found here. Transfer function analyses, which have been neglected in epidemiology, were applied. These models, with ln(S) as the input parameter, in spite of their simplicity, could be linked closely to conventional formulations of the transmission process and were highly effective in predicting the number infected. By contrast, transfer function models with ln(N) as the input parameter were less successful in predicting the number infected and/or were more complex and more difficult to interpret. Nonetheless, overall, we contend that while monitoring numbers susceptible has most to offer, monitoring overall abundance may provide valuable insights into the dynamics of infection.",
keywords = "transmission, wildlife, dynamics, transfer function, zoonoses",
author = "Michael Begon and Sandra Telfer and Sarah Burthe and Xavier Lambin and Steve Patterson",
year = "2009",
month = "3",
doi = "10.1016/j.epidem.2008.10.001",
language = "English",
volume = "1",
pages = "35--46",
journal = "Epidemics",
issn = "1755-4365",
publisher = "Elsevier",
number = "1",

}

TY - JOUR

T1 - Effects of abundance on infection in natural populations

T2 - field voles and cowpox virus

AU - Begon, Michael

AU - Telfer, Sandra

AU - Burthe, Sarah

AU - Lambin, Xavier

AU - Patterson, Steve

PY - 2009/3

Y1 - 2009/3

N2 - Detailed results on the dynamics of cowpox virus infection in four natural populations of the field vole, Microtus agrestis, are presented. Populations were sampled every 4 weeks (8 weeks in mid-winter) for 6 years. The purpose was to examine the relationships between overall or susceptible host abundance (N, S) and both the number of infected hosts (I) and the prevalence of infection (I/N). Overall, both I and I/N increased with N. However, evidence for a threshold abundance, below which infection was not found, was at best equivocal in spite of the wide range of abundances sampled. Cross-correlation analyses reflected annual and multi-annual cycles in N, I, S and I/N, but whereas N was most strongly correlated with contemporary values of I and I/N, in the case of S, the strongest correlations were with values 1 to 2 months preceding the values of I and I/N. There was no evidence for a ‘juvenile dilution effect’ (prevalence decreasing with abundance as new susceptibles flush into the population) and only weak evidence of a time-delayed effect of abundance on the number infected. We argue that these effects may occur only in systems with characteristics that are not found here. Transfer function analyses, which have been neglected in epidemiology, were applied. These models, with ln(S) as the input parameter, in spite of their simplicity, could be linked closely to conventional formulations of the transmission process and were highly effective in predicting the number infected. By contrast, transfer function models with ln(N) as the input parameter were less successful in predicting the number infected and/or were more complex and more difficult to interpret. Nonetheless, overall, we contend that while monitoring numbers susceptible has most to offer, monitoring overall abundance may provide valuable insights into the dynamics of infection.

AB - Detailed results on the dynamics of cowpox virus infection in four natural populations of the field vole, Microtus agrestis, are presented. Populations were sampled every 4 weeks (8 weeks in mid-winter) for 6 years. The purpose was to examine the relationships between overall or susceptible host abundance (N, S) and both the number of infected hosts (I) and the prevalence of infection (I/N). Overall, both I and I/N increased with N. However, evidence for a threshold abundance, below which infection was not found, was at best equivocal in spite of the wide range of abundances sampled. Cross-correlation analyses reflected annual and multi-annual cycles in N, I, S and I/N, but whereas N was most strongly correlated with contemporary values of I and I/N, in the case of S, the strongest correlations were with values 1 to 2 months preceding the values of I and I/N. There was no evidence for a ‘juvenile dilution effect’ (prevalence decreasing with abundance as new susceptibles flush into the population) and only weak evidence of a time-delayed effect of abundance on the number infected. We argue that these effects may occur only in systems with characteristics that are not found here. Transfer function analyses, which have been neglected in epidemiology, were applied. These models, with ln(S) as the input parameter, in spite of their simplicity, could be linked closely to conventional formulations of the transmission process and were highly effective in predicting the number infected. By contrast, transfer function models with ln(N) as the input parameter were less successful in predicting the number infected and/or were more complex and more difficult to interpret. Nonetheless, overall, we contend that while monitoring numbers susceptible has most to offer, monitoring overall abundance may provide valuable insights into the dynamics of infection.

KW - transmission

KW - wildlife

KW - dynamics

KW - transfer function

KW - zoonoses

U2 - 10.1016/j.epidem.2008.10.001

DO - 10.1016/j.epidem.2008.10.001

M3 - Article

VL - 1

SP - 35

EP - 46

JO - Epidemics

JF - Epidemics

SN - 1755-4365

IS - 1

ER -