Bovine tuberculosis in Northern Ireland: risk factors associated with time from post-outbreak test to subsequent herd breakdown.

Autor: Doyle LP; Veterinary Epidemiology Unit, Department of Agriculture and Rural Development for Northern Ireland, Dundonald House, Belfast BT4 3SB, UK. Electronic address: liam.doyle@dardni.gov.uk., Gordon AW; Agri-Food and Biosciences Institute, Newforge Lane, Belfast BT9 5PX, UK., Abernethy DA; Department of Veterinary Tropical Diseases, Veterinary Faculty, University of Pretoria, South Africa., Stevens K; Veterinary Epidemiology, Economics and Public Health Group, Production and Population Health Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
Jazyk: angličtina
Zdroj: Preventive veterinary medicine [Prev Vet Med] 2014 Sep 01; Vol. 116 (1-2), pp. 47-55. Date of Electronic Publication: 2014 Jun 26.
DOI: 10.1016/j.prevetmed.2014.06.010
Abstrakt: Compulsory bovine tuberculosis testing has been implemented since 1959 in Northern Ireland. Initial rapid progress in the eradication of the disease was followed by a situation where disease levels tended to fluctuate around a low level. This study explores recrudescence of bovine tuberculosis (bTB) in Northern Ireland herds by assessing risk factors associated with time from the six-month post-outbreak skin test until a further herd breakdown. Bovine herds (n=3377) were recruited in 2002 and 2003 and their survival analysed using Kaplan-Meier survival estimates and a Cox proportional hazards model, with follow-up extending to August 2008. Exclusion criteria applied for study entry were bTB infection in a contiguous herd, changing of post restriction test to one of a higher risk status or chronic infection. Chronic infection was defined as any situation where disclosure preceded the post-outbreak test by two years or more. The application of these exclusion criteria meant that herds recruited to the study were largely cleared of infection and not directly contiguous to other infected herds. Of the 3377 herds, 1402 (41.5%) suffered a further herd breakdown before the end of follow-up. Median survival time was 582 days (interquartile range=336-1002 days). Breakdown severity (defined as the number of Single Intradermal Comparative Tuberculin Test (SICTT) reactors at disclosure test), local bTB prevalence, herd size and type were identified as significant risk factors (p<0.05), as was the purchase of higher numbers (n>27.38 per year) of cattle. Consistent with other studies this work shows bTB confirmation to not be predictive of a future herd breakdown. This work shows bTB history as not being a risk factor for a future breakdown. This result could be reflective of the exclusion criteria used in the study, which may have selected for incidents where historical status was of less importance.
(Copyright © 2014 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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