Assessing the Effectiveness of Tuberculosis Management in Brushtail Possums (Trichosurus vulpecula), through Indirect Surveillance of Mycobacterium bovis Infection Using Released Sentinel Pigs
Trends in prevalence of culture-confirmed tuberculosis and of apparent annual incidence of new M. bovis infections among successive cohorts of pigs from Molesworth Station (a) and Clarence Reserve (b) study areas. Dashed lines represent 5-year linear trend lines fitted to the data from 2007 to 2011. Arrows refer to point of poison control of possums (Molesworth Station only) for which the 2008 cohort data were split into prepoison (Jan–Sept) and postpoison (Oct–Dec) portions. Historical prevalence/incidence values are presented for three sets of similar surveys conducted over the periods 1999–2003, 2003-2004, and 2005–2007; data in these historical surveys are presented for total pigs and are not differentiated according to birth year cohort. * includes one set of Molesworth surveys in 2005–2007 where predominantly yearling pigs were sampled (mean age 7.8 months, ); hence an extremely high AAL value of 2.88 was recorded.