Options for the control of disease 3: Targeting the environment

Management of wildlife disease can be targeted at pathogens, hosts or vector populations, but may also focus on the environment. As constituent elements of any given environment, resident wildlife populations, and their pathogens, may be profoundly influenced by environmental change, in terms of their abundance, distribution and behaviour. Hence, it is reasonable to expect that incorporation of environmental manipulation into a programme to control wildlife diseases may potentially result in outcomes as effective as direct intervention aimed at hosts, pathogens and vectors. Environments are not static, but are naturally dynamic, complex systems that exert strong influences on patterns of disease via their impact on hosts, pathogens, vectors and the interactions between them. Consequently, it can be difficult to identify which environmental variables are most important in influencing disease dynamics and hence which elements to target as part of a disease management programme. Nevertheless, environmental management has been used extensively to control diseases in wildlife in many parts of the world, with some apparent success (Wobeser 2002). Anecdotal information arising from disease management projects and from studies of wildlife behavioural ecology and disease epidemiology suggests that environmental manipulation may offer potential opportunities for the long-term management of many diseases of wildlife. However, while more direct approaches to disease management, such as host population reduction (see Chapter 7) or vaccination (see Chapter 6), might have rapid effects, the benefits of environmental manipulation are likely to take much longer to accrue.