August 9, 2021

expert comments about TB in alpacas and other animals

Following recent news surrounding the case of Geronimo the alpaca, here is a general comment from Professor James Wood about bovine tuberculosis (bTB) in animals including alpacas.

Prof James Wood, Head of Department of Veterinary Medicine, University of Cambridge, said:

“Cattle are affected by bovine TB and the infection may spread to and from other species, including badgers and alpacas.  There is a national disease control policy for bovine TB, in which animals found to be infected are killed to avoid them spreading the infection.

“In general, when testing for bovine TB, living animals are tested to see if they have mounted an immune response to the bacterium that causes the disease.  Most typically, this is done through a skin test (like the skin test used in humans), when a sterile protein mix from the bacterium is injected and then the reaction is evaluated 3 days later.  This skin test assesses the white blood cell response to infection.

“Blood tests are also used in cattle, usually also to measure the white blood cell reactivity to the infection (so called gamma interferon assays, which are also used in humans for TB).  Tests for antibodies in blood have also started to be used and two have been carefully validated for use.  One of them has been recommended by Alpaca owners as the test of choice for bovine TB in that species.

“After death, often in a slaughterhouse, efforts are also made to isolate the bacterium from animals, typically from organs or glands (lymph nodes) that show signs of disease, although this approach is slow and may fail to detect positives (lots of false negatives).”

Declared interests

Prof James Wood: “recipient of funds from Defra and UKRI for research on bTB and a member of Defra’s bovine TB Partnership Group.”