BCG-vaccinated cattle less infectious to other cattle, study finds
The UK government is currently conducting its own research into a deployable vaccine for cattle.
TB-infected cattle that have previously been given the Bacillus Calmette-Guérin (BCG) vaccine are less infectious to other cattle, a new study has found.
The research, led by the University of Cambridge and Penn State University, found that the BCG vaccine reduced TB transmission between cattle by 74 per cent per cent.
It is the first time this indirect benefit of the vaccine has been measured by scientists.
Conducted in Ethiopia, the study made use of livestock census and movement data to develop a transmission model.
Ethopia has the largest cattle population in Africa, but currently lacks a control programme for bovine TB. Intensive testing and slaughtering infected animals, as carried out in countries such as the UK, is considered to be unfeasible to implement in Ethiopia and other similar countries due to social and economic reasons.
Professor Conlan, associate professor of epidemiology at the University of Cambridge's Department of Veterinary Medicine and one of the authors of the study, said: "Results of the model suggest that vaccinating calves within the dairy sector of Ethiopia could reduce the reproduction number of the bacterium -- the R0 -- to below 1, arresting the projected increase in the burden of disease and putting herds on a pathway towards elimination of TB.”
The UK government is currently conducting its own research into creating a deployable vaccine and new DIVA skin test for bovine TB. Currently, the UK does not use the BCG vaccine because it can lead to vaccinated cattle giving false positive test results.
James Wood, Alborada professor of equine and farm animal science at the University of Cambridge's Department of Veterinary Medicine, said: "For over twenty years the UK government has pinned hopes on cattle vaccination for bovine tuberculosis as a solution to reduce the disease and the consequent costs of the controls.
“These results provide important support for the epidemiological benefit that cattle vaccination could have to reduce rates of transmission to and within herds."
The study has been published in the journal Science.
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