The hidden burden of bovine Tuberculosis

Oct 18, 2012

Up to 21% of herds clearing restrictions for bovine Tuberculosis (bTB) in Great Britain may be harbouring infection, according to a study published in PLOS Computational Biology this week. A cross-disciplinary group of experts in the Disease Dynamics Unit, University of Cambridge and the Animal Health and Veterinary Laboratories Agency has used mathematical models to provide the first empirical estimates of the efficiency of cattle-based controls for bovine tuberculosis (bTB). These models were developed to help policy-makers understand and control bTB as part of a project funded by Defra.

bTB was previously transmitted from cattle to people in untreated milk. However, stringent measures, including , introduced by the in the 1930s have practically eliminated the risk to people. A rigorous policy reduced disease in to minimal levels in the 1960s, but the past 25 years have seen the disease return; around 26,000 cattle were slaughtered for bTB control in England in 2011 alone.

The models were constructed using data taken from infected herds detected through routine surveillance, either in the slaughterhouse, or through routine whole herd tests between 2003-2005.

"Around 38% of herds officially cleared of disease experience a recurrent incident within 24 months, suggesting that infection persists in herds," said lead author Dr Andrew Conlan. "We developed mathematical models, fitted carefully to extensive surveillance and testing data to estimate the efficiency of testing directly from epidemiological data rather than relying on expert opinion. Another important result is that we estimate a high rate of re-introduction of infection into herds. This suggests that eliminating the hidden burden of infection alone will not be enough to reduce rates of recurrence."

The work focused on what happens within infected herds. These models cannot predict the extent to which hidden infection contributes to transmission between herds. The models also do not distinguish between the relative roles of the badger and cattle in the spread of bTB. Quantifying the persistence of at the herd level is an important first step to answering these questions and provides a basis for developing more complex national models of transmission.

Financial disclosure: This work was funded by Defra, United Kingdom under contract SE3230. AJKC was funded under this grant (PI/T/WL/07/46), sponsored by the Veterinary Laboratories Agency. JLNW was also supported by the Alborada Trust and the RAPIDD program of the Science & Technology Directorate, Department of Homeland Security. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing interests: The authors have declared that no competing interests exist.

Explore further: A molecular compass for bird navigation

More information: Conlan AJK, McKinley TJ, Karolemeas K, Pollock EB, Goodchild AV, et al. (2012) Estimating the Hidden Burden of Bovine Tuberculosis in Great Britain. PLoS Comput Biol 8(10): e1002730. doi:10.1371/journal.pcbi.1002730

add to favorites email to friend print save as pdf

Related Stories

Research suggests why bovine TB continues to spread

May 22, 2012

The failure of the current bovine tuberculosis (TB) eradication programme could be partly due to a parasitic worm that hinders the tests used to diagnose TB in cows, according to new research published this week.

Bovine TB testing under scrutiny

Oct 27, 2011

Planned changes to the way vets are allowed to conduct TB tests could have a dramatic impact on rural veterinary practices and fail to address quality control issues surrounding tests for bovine tuberculosis, ...

Recommended for you

A molecular compass for bird navigation

54 minutes ago

Each year, the Arctic Tern travels over 40,000 miles, migrating nearly from pole to pole and back again. Other birds make similar (though shorter) journeys in search of warmer climes. How do these birds manage ...

100,000 bird samples online

2 hours ago

The Natural History Museum (NHM) in Oslo has a bird collection of international size. It is now available online.

New genetic technologies offer hope for white rhino

4 hours ago

With support from the Seaver Institute, geneticists at San Diego Zoo Institute for Conservation Research are taking the initial steps in an effort to use cryopreserved cells to bring back the northern white rhino from the ...

Cats put sight over smell in finding food

19 hours ago

Cats may prefer to use their eyes rather than follow their nose when it comes to finding the location of food, according to new research by leading animal behaviourists.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.