Network of Contacts between Cattle Herds in a French Area Affected by Bovine Tuberculosis in 2010

Abstract

France attained 'Officially Tuberculosis-Free' status in 2000. However, the Côte d'Or department (a French administrative unit) has since seen an increase in bovine tuberculosis (bTB) cases, with 35% of cases attributed to neighbourhood contamination. The aim of this study was to investigate the characteristics of neighbourhood contacts in an area affected by bTB in 2010, through the use of social network methods. We carried out a survey to determine the frequency and distribution of between-herd contacts in an area containing 22 farms. Contacts were weighted, as not all types of contact carried the same risk of bTB transmission. Cattle movement was considered to be associated with the highest risk, but was not observed within the studied area during the study period. Contact with wild boars was the most frequent type of contact, but was associated with a very low risk. Direct cattle-to-cattle contacts in pasture and contacts with badger latrines were less frequent, but entailed a greater risk of M. bovis transmission. Centrality values were heterogeneous in these two networks. This would enable the disease to spread more rapidly at the start of epidemics than in a perfect randomly mixed population. However, this situation should also result in the total number of infected herds being smaller. We attributed 95% of the contacts to direct contact in pasture or contact with wild boars or badger latrines. Other kinds of contact occurred less frequently (equipment sharing, cattle straying) or did not occur at all (attendance at a show). Most of the contact types were correlated, but none was sufficient in itself to account for all contacts between one particular farm and its neighbours. Contacts with neighbours therefore represent a challenge for the implementation or improvement of control measures.

Genetic Evolution of Mycobacterium bovis Causing Tuberculosis in Livestock and Wildlife in France since 1978

“…bovis population in the studied period. Indeed, suckling farms present strong bTB risk factors, such as operating farm over several premises, large land coverage, long stay in pastures that favors neighboring risk and environmental contamination by wildlife contact [ 33 ]. Difficulties are associated to the reduced man surveillance power of big herds in animals which are more difficult to contain than milk cattle, thus rendering veterinary handling more delicate [ 34 ].…”

Epidemiologic characterization of bovine tuberculosis in the State of Rondônia, Brazil

“…The classic risk factor for bovine tuberculosis is the introduction of animals with unknown sanitary conditions (DE LA CRUZ et al, 2014;DOMMERGUES et al, 2012;GILBERT et al, 2005;GRISI-FILHO et al, 2011). In fact, the only risk factor of bovine tuberculosis in Rondônia was the acquisition of animals.…”

Spatial Dynamics of Bovine Tuberculosis in the Autonomous Community of Madrid, Spain (2010–2012)

“…Such result may be due to a shared contact network (between-herd contacts in shared pastures, controlled and uncontrolled local cattle movements, exposure to infected wildlife or other as yet unidentified local source in herds located in the same vicinity). Neighboring contacts can be highly variable between and within regions [55] , and no information was available here to further characterize the contact networks between farms in the ACM. However, the lack of autocorrelation in the residuals of the best model found for the whole region suggests that at the regional level variables included in the final model (use of IFN-γ assay, number of reactors in the first herd test and previous history of bovine tuberculosis) may account for the majority of the spatial variation of the β coefficient.…”