Modelling transmission dynamics of paratuberculosis of red deer under pastoral farming conditions

Heuer, C.; Mitchell, R. M.; Schukken, Y. H.; Lu, Z.; Verdugo, C.; Wilson, P. R.

Abstract

This study aimed to develop a mathematical model describing the dynamics of paratuberculosis (PTB) in red deer (Cervus elaphus) under pastoral farming conditions in New Zealand. The model examined infectivity differences between ovine and bovine strains of Mycobacterium avium subspecies paratuberculosis (MAP) and seasonality of MAP survival. We also evaluate variable use of pasture and the effect of management interventions on the infection prevalence and annual clinical incidence of PTB. A state-transition model was developed and calibrated to observed data on both prevalence of infection and incidence of clinical PTB. To accommodate specific PTB features for deer, the model included a fast and a slow track for progression of infection to disease. MAP on pasture was the source for horizontal transmission and infected dams for vertical transmission. In the presence of a single strain, an infectivity reduction of up to 80% allowed MAP to persist in the herd (R-0 > 1). For mixed infection by two strains however, a 30% reduction in infectivity of one strain was sufficient to outcompete a strain with lower infectivity, suggesting that mixed infection of MAP strains with different infectivity may not be common in deer. The model showed that seasonal variation of MAP survival on pasture had little impact on transmission dynamics, and that rotational grazing with pasture spelling vs. permanent grazing of the same paddock reduced both infection prevalence and clinical PTB by about 50%. Based on model outputs, early detection of young deer in a high-shedding state was the most effective means of controlling PTB among the tested scenarios. (C) 2012 Elsevier B.V. All rights reserved.

Más información

Título según WOS: ID WOS:000307155000007 Not found in local WOS DB
Título de la Revista: PREVENTIVE VETERINARY MEDICINE
Volumen: 106
Número: 1
Editorial: ELSEVIER SCIENCE BV
Fecha de publicación: 2012
Página de inicio: 63
Página final: 74
DOI:

10.1016/j.prevetmed.2012.02.021

Notas: ISI