OBJECTIVE: To estimate the likely geographical distribution and flock-prevalence of ovine Johne's disease (OJD) in Australia. DESIGN: A cross-sectional study design was used. PROCEDURE: The results of abattoir surveillance for OJD carried out during 2000 were analysed to estimate the prevalence of infected flocks in three regions of New South Wales and in other States. A Bayesian approach was used to adjust apparent prevalence estimates for the assumed flock-sensitivity and flock-specificity of abattoir surveillance, and to allow for uncertainty about the true values of these measures. RESULTS: The 95% probability limits for flock-prevalence at 31 December 2000 were 0.04%-1.5%, 8%-15% and 29%-39% for low, moderate and high prevalence regions of New South Wales respectively. The other States generally had an upper 97.5% probability limit of about 1% or less. Based on these estimates about 6 to 10% of flocks in New South Wales and 2.4 to 4.4% of flocks Australia-wide are likely to be infected. CONCLUSION: This study suggests that OJD has a highly clustered distribution in Australia, and provides estimates of the prevalence of infected flocks by State or region. Based on this analysis there were probably between 2000 and 3700 infected flocks in Australia at 31 December 2000, with more than 80% of these in a relatively small geographic area of central and southern New South Wales. Some States, such as Queensland and Western Australia, may have a prevalence equal or close to 0%, however the technique used was unable to demonstrate the absence of infection in these States with the intensity of surveillance undertaken to date.
OBJECTIVE: To estimate the likely geographical distribution and flock-prevalence of ovine Johne's disease (OJD) in Australia. DESIGN: A cross-sectional study design was used. PROCEDURE: The results of abattoir surveillance for OJD carried out during 2000 were analysed to estimate the prevalence of infected flocks in three regions of New South Wales and in other States. A Bayesian approach was used to adjust apparent prevalence estimates for the assumed flock-sensitivity and flock-specificity of abattoir surveillance, and to allow for uncertainty about the true values of these measures. RESULTS: The 95% probability limits for flock-prevalence at 31 December 2000 were 0.04%-1.5%, 8%-15% and 29%-39% for low, moderate and high prevalence regions of New South Wales respectively. The other States generally had an upper 97.5% probability limit of about 1% or less. Based on these estimates about 6 to 10% of flocks in New South Wales and 2.4 to 4.4% of flocks Australia-wide are likely to be infected. CONCLUSION: This study suggests that OJD has a highly clustered distribution in Australia, and provides estimates of the prevalence of infected flocks by State or region. Based on this analysis there were probably between 2000 and 3700 infected flocks in Australia at 31 December 2000, with more than 80% of these in a relatively small geographic area of central and southern New South Wales. Some States, such as Queensland and Western Australia, may have a prevalence equal or close to 0%, however the technique used was unable to demonstrate the absence of infection in these States with the intensity of surveillance undertaken to date.
Authors: Zhiyong Zhou; Rebecca Mans Mitchell; Julie Gutman; Ryan E Wiegand; Dyson A Mwandama; Don P Mathanga; Jacek Skarbinski; Ya Ping Shi Journal: Malar J Date: 2014-12-18 Impact factor: 2.979
Authors: Mahdi Pourmahdi Borujeni; Mohammad Rahim Haji Hajikolaei; Masoud Ghorbanpoor; Hamzeh Elhaei Sahar; Saeed Bagheri; Sanaz Roveyshedzadeh Journal: Vet Med Sci Date: 2021-07-06