Estimates for local and movement-based transmission of bovine tuberculosis in British cattle

Abstract

Both badgers and livestock movements have been implicated in contributing to the ongoing epidemic of bovine tuberculosis (BTB) in British cattle. However, the relative contributions of these and other causes are not well quantified. We used cattle movement data to construct an individual (premises)-based model of BTB spread within Great Britain, accounting for spread due to recorded cattle movements and other causes. Outbreak data for 2004 were best explained by a model attributing 16% of herd infections directly to cattle movements, and a further 9% unexplained, potentially including spread from unrecorded movements. The best-fit model assumed low levels of cattle-to-cattle transmission. The remaining 75% of infection was attributed to local effects within specific high-risk areas. Annual and biennial testing is mandatory for herds deemed at high risk of infection, as is pre-movement testing from such herds. The herds identified as high risk in 2004 by our model are in broad agreement with those officially designated as such at that time. However, border areas at the edges of high-risk regions are different, suggesting possible areas that should be targeted to prevent further geographical spread of disease. With these areas expanding rapidly over the last decade, their close surveillance is important to both identify infected herds quickly, and limit their further growth.

The clinical and serological diagnosis of Mycobacterium bovis in blood and milk serums of lactating cows by IDEXX ELISA test in Wasit and Dhi-Qar provinces/Iraq

“…Although, the role of local spread of bTB in some areas is not well understood, bTB testing had a significant impact on the expansion and long distance spread of disease, especially on transmission to areas with relatively low incidence. 32 A variable incidence of bTB may effect through several modes like the geographical position features; Agroecological system; public health condition for humans and animals; herd size, farm management and grazing practice; age, breed, gender and body condition score of animals; compelled organizing schemes of the veterinary departments; concurrent diseases, host genetic variation, immune suppression, cattle behavior, physiological status, cows scheme form, feeding system, treatments with control program, environments or weather, pathological variations. [33][34][35] Whilst the respiratory disorders, emaciation, rough hair coat, decrease in milk production and presence of reproductive failures shows the most prevalent signs of positive cows in blood and milk groups; the enlargement of lymph nodes, loss of appetites and feces abnormalities manifested the lowers, with presence of some differences between both serum groups.…”

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

“…In Green et al (2008) Great Britain bTB outbreak data for 2004 was used to estimate that 16% of herd infections were directly related to cattle movements. The idea of herd infection initiated by purchase of infected animals is supported by Berrian et al (2012).…”

Scientific report on the effects of farming systems on dairy cow welfare and disease

“…It seems that stress and reduced welfare can enhance the susceptibility for infection by lowering the infection threshold, or the amount of pathogen needed to initiate an infection in an animal or overwhelm the immune defence system. The effects of transport are of considerable importance for dairy cow welfare not only because of the acute or delayed effects on the animal being transported but also marketing and transport of cows and bulls are important ways in which many infectious diseases may be disseminated to dairy herds and then in turn increase the incidence and prevalence of disease and poor welfare in those herds (see for example Green et al 2008b andEFSA, 2004).…”