Davidson, R.S., Marion, G., White, P.C.L. and Hutchings, M.R.
Epidemiology and Infection 137, 131-138.
stochastic model; wildlife disease; control strategies;
||Reduction in wildlife populations is a common method for the control of livestock infections
which have wildlife hosts, but its success is dependent on the characteristics of the infection itself,
as well as on the spatial and social structure of the wildlife host. Paratuberculosis (Mycobacterium
avium subsp. paratuberculosis ; Map) is a widespread and difficult infection to control in livestock
populations and also has possible links to Crohn's disease in humans. Rabbits have recently been
identified as a key wildlife species in terms of paratuberculosis persistence in the environment and
risk to the wider host community, including cattle. Here we use a spatially explicit stochastic
simulation model of Map dynamics in rabbit populations to quantify the effects of rabbit
population control on infection persistence. The model parameters were estimated from empirical
studies of rabbit population dynamics and rabbit-to-rabbit routes of Map transmission. Three
rabbit control strategies were compared: single unrepeated population reductions based on
removing individual animals ; single unrepeated population reductions based on removal of entire
social groups; and repeated annual population reductions based on removing individual animals.
Unrealistically high rabbit culls (>95% population reduction) are needed if infection is to be
eradicated from local rabbit populations with a single one-off population reduction event, either
of individuals or social groups. Repeated annual culls are more effective at reducing the
prevalence of infection in rabbit populations and eradicating infection. However, annual
population reductions of >40% are required over extended periods of time (many years). Thus,
using an approach which is both highly conservative and parsimonious with respect to estimating
lower bounds on the time to eradicate the infection, we find that Map is extremely persistent in
rabbit populations and requires significant and prolonged effort to achieve control.