The objectives of this study were to estimate the dairy herd-level prevalence of Johne's disease (JD) in Utah and nearby areas of the intermountain west and to estimate the sensitivity of a single bulk-tank milk test for JD detection. Two milk samples from all bulk tanks on the study farms were collected 1 mo apart. Samples were frozen and shipped to a laboratory for JD testing. An ELISA to measure total IgG antibody specific against Mycobacterium avium ssp. paratuberculosis, the etiological agent that causes JD, and a quantitative real-time PCR to detect M. avium ssp. paratuberculosis DNA were used; both tests were designed for bulk milk. Of the dairy farms in the study area, 170/246 (69%) participated. Positive JD results were found in bulk milk from 67/170 (39%) of dairy farms in Utah and adjacent areas. There were 138 JD-positive bulk-tank results from 241 bulk-tank samples from the 67 positive herds. The sensitivity of the bulk milk testing for detection of JD was 138/241(57%). From the 103 JD-negative farms, 235 bulk-tank samples tested negative for JD. The probability of false-negative results on a single bulk-milk sample was (1 - 0.57) = 0.43. For farms with 1 bulk tank, 2 samples collected 1 mo apart, with both samples testing negative (by both ELISA and quantitative real-time PCR) for JD, the true-negative probability was [1 - (0.43)(2)] = (1 - 0.18) = 82%. For farms with at least 2 bulk tanks, at least 4 samples tested, with all results negative for JD, the true-negative probability was at least 97%. Results support other estimates that prevalence of JD has increased over the last 15 to 20 yr. However, the prevalence detected was 3 times that from a recent report where 13% of dairy herds in the western US were positive. The increase in JD suggests that current control programs, at least as applied, are not effective. Bulk milk testing is a practical way to screen dairy herds for presence of JD. Studies are needed regarding the use of individual cow milk tests for accuracy, practicality, and effectiveness in reducing the prevalence of JD in dairy herds.
A cross-sectional survey was undertaken on dead pigeons to explore the diseases and conditions associated with the death of pigeons reared at smallholdings and sold at live-bird markets in Bangladesh. 108 dead pigeons were collected from 2 live-bird markets-one in Dhaka and other based at Chittagong districts, 38 smallholdings, of which 20, 3, 3, 5 and 7 were located in Jessore, Dhaka, Chittagong, Magura and Jhenaidah districts respectively. Initially the collected dead pigeons were preserved at the households' refrigerators and then transferred to the department of Microbiology, Chittagong Veterinary and Animal Sciences University, where they were further frozen at -84°C until investigated. All the collected dead pigeons were thoroughly examined postmortem. From each of the dead pigeon (except decomposed carcasses) bacteriological examination done through taking samples from the liver with sterile cotton swabs, and inoculated onto at least two media-McConkey and Mueller-Hinton agar (supplemented with 5% defrinated sheep blood). To identify the organism for any bacterial growths on these two media were examined using the standard procedures. The 4 major disease/conditions associated with the deaths of the pigeons were cervical disruption & related haemorrhages (17.6%), colibacillosis (13.89%), external injuries (8.33%) and morbus cordis (10.18%).
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