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Context-dependent survival, fecundity and predicted population-level consequences of brucellosis in African buffalo

Journal of Animal Ecology

By:
, , , , and
https://doi.org/10.1111/1365-2656.12356

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Abstract

  1. Chronic infections may have negative impacts on wildlife populations, yet their effects are difficult to detect in the absence of long-term population monitoring. Brucella abortus, the bacteria responsible for bovine brucellosis, causes chronic infections and abortions in wild and domestic ungulates, but its impact on population dynamics is not well understood.
  2. We report infection patterns and fitness correlates of bovine brucellosis in African buffalo based on (1) 7 years of cross-sectional disease surveys and (2) a 4-year longitudinal study in Kruger National Park (KNP), South Africa. We then used a matrix population model to translate these observed patterns into predicted population-level effects.
  3. Annual brucellosis seroprevalence ranged from 8·7% (95% CI = 1·8–15·6) to 47·6% (95% CI = 35·1–60·1) increased with age until adulthood (>6) and varied by location within KNP. Animals were on average in worse condition after testing positive for brucellosis (F = −5·074, P < 0·0001), and infection was associated with a 2·0 (95% CI = 1·1–3·7) fold increase in mortality (χ2 = 2·039, P = 0·036). Buffalo in low body condition were associated with lower reproductive success (F = 2·683, P = 0·034), but there was no association between brucellosis and pregnancy or being observed with a calf.
  4. For the range of body condition scores observed in the population, the model-predicted growth rate was λ = 1·11 (95% CI = 1·02–1·21) in herds without brucellosis and λ = 1·00 (95% CI = 0·85–1·16) when brucellosis seroprevalence was 30%.
  5. Our results suggest that brucellosis infection can potentially result in reduced population growth rates, but because these effects varied with demographic and environmental conditions, they may remain unseen without intensive, longitudinal monitoring.

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Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Context-dependent survival, fecundity and predicted population-level consequences of brucellosis in African buffalo
Series title:
Journal of Animal Ecology
DOI:
10.1111/1365-2656.12356
Volume:
84
Year Published:
2015
Language:
English
Publisher:
Wiley
Contributing office(s):
Northern Rocky Mountain Science Center
Description:
11 p.
First page:
999
Last page:
1009
Country:
South Africa
Other Geospatial:
Kruger National Park
Online Only (Y/N):
N
Additional Online Files (Y/N):
N