Control of endemic bovine Tb in New Zealand possum populations: results from a simple model.
Modified versions of the classic disease/host differential equation models were applied to rates of harvesting, sterilization and vaccination required to eliminate bovine tuberculosis (Tb) in New Zealand possum (Trichosurus vulpecula) populations. The threshold density of susceptible possums for disease elimination is about half the uncontrolled population density. Simulation of realistic control policies over time suggests that the most cost-effective options currently available are widespread poisoning with 1080 every 6 years, a single intensive poisoning operation followed by intensive ground control, or a poisoning operation followed by targeted trapping. Controlled areas must be at least 50 km2 to prevent breakdown of control by immigration from surrounding diseased populations. The best option for longer-term management may be by control of reproduction, preferably using microbiological agents. Vaccination is the least promising option.