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Estimated M. bovis Seroprevalence Was 26.6% in Exmoor Red Deer

Wild red deer herd on Exmoor
Research · Disease, parasites & microbiology

An estimated 26.6% of sampled red deer (Cervus elaphus) in the Exmoor area of southwest England had antibodies consistent with infection by Mycobacterium bovis, according to a study first published online on 17 April 2026. Seropositivity shows that the immune system has responded to the bacterium; it is not the same as directly detecting viable bacteria in the animal at the time of sampling. M. bovis causes bovine tuberculosis, a chronic infectious disease, and can cause disease in cattle, deer, badgers, people and other mammals.

Researchers tested post-mortem blood samples from 432 free-ranging deer collected during annual population-control culls over a 12-month period. Red deer made up 347 of the animals, while the sample also included 63 European fallow deer (Dama dama), 19 European roe deer (Capreolus capreolus) and one muntjac; species was not recorded for two animals. Overall, 69 samples, or 16.0%, were positive in the antibody test. Because the test has only moderate sensitivity in deer, some infected animals can test negative; the researchers therefore adjusted the observed positivity to estimate the underlying seroprevalence.

Estimated true seroprevalence was 26.6% in red deer

After accounting for the imperfect diagnostic accuracy of the test, the estimated true seroprevalence was 27.4% across the full sample and 26.6% in red deer. The corresponding estimates were 27.2% in fallow deer and 36.8% in roe deer. The apparently higher roe-deer value was based on only 19 animals, and the authors found little evidence of a real difference between deer species. They likewise found little evidence of overall differences between sexes or age classes, although no animals under one year old tested positive.

Opportunistic carcass sampling limits population-wide interpretation

The authors note that the carcasses were sampled opportunistically, so sampling bias cannot be excluded, and that the seroprevalence estimate depends on the assumed sensitivity and specificity of the antibody test. They describe the overall estimate as being at the upper end of values previously reported for deer worldwide and recommend interpreting it together with species ecology, disease pathology and other epidemiological evidence when assessing transmission risks between cattle and wild deer.

Sources and image credit

  1. Jinks, R., Hollingdale, A., Avigad, R., Velarde, J., Pugsley, C., de la Rua-Domenech, R., Pritchard, C., Roberts, T., Pastor, J., Robinson, N., Maynes, R., Withenshaw, S., & Smith, G. (2026). Estimating the seroprevalence of Mycobacterium bovis infection in a wild deer population in southwest England. Veterinary Record, 199(4), e147–e154. https://doi.org/10.1002/vetr.70547Primary research article first published online 17 April 2026. Post-mortem blood from 432 free-ranging deer in the Exmoor area was tested for M. bovis antibodies. Estimated true seroprevalence was 27.4% overall, 26.6% in red deer, 27.2% in fallow deer and 36.8% in roe deer; the authors note convenience-sampling and diagnostic-test limitations.

Image: John Shortland / Wikimedia Commons — wild red deer on Exmoor, England; geographically representative of the study area, not identified as animals from the serology sample; cropped to 16:9. · CC BY 2.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Disease, parasites & microbiology

SPECIES IN THIS STORY

Species in this story

Red Deer Cervus elaphus Explore species European Fallow Deer Dama dama Explore species European Roe Deer Capreolus capreolus Explore species

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