Scientists from the University of Edinburgh, in collaboration with the APHA (Animal and Plant Health Agency) amongst others, analysed the entire genetic make-up of the mycobacteria that causes TB (Mycobacterium bovis) from 230 badgers and 189 cattle over a 15 year period in a process known as whole genome sequencing.
The official test to confirm a herd has an Officially TB free status is called the Tuberculin skin test (SICCT). Its sensitivity – the ability of the test to correctly identify those animals with the disease – varies between 50 and 90% depending on the conditions under which it is carried out. This means that infected animals are being missed; leaving them in the herd to infect others.
Responding to the research, PBD Biotech’s Chief Scientific Officer Dr Cath Rees said:
“This paper provides interesting new insights into the reservoir of M. bovis infection that exists in cattle and badger populations. The findings show the ease with which cattle can transmit TB to other cattle, at least twice as often than infection between badger and cow. The study demonstrates why it is vital that an accurate diagnostic is used to root out TB from a herd – ensuring no infected animals remain.
“The known limitations of the existing tests cast doubt on what ‘TB-free status’ now genuinely means. This is exactly why we have developed Actiphage – to directly detect and identify live mycobacteria, providing another way to detect infection when tests based on an immune response fail.”
Actiphage® is a rapid test for the presence of viable mycobacteria in blood or milk samples. It can provide accurate results within hours and can detect very low levels of mycobacteria, before the animal starts shedding bacteria into the environment. It therefore enables improved disease management.
Authors of the ‘Combining genomics and epidemiology to analyse bi-directional transmission of Mycobacterium bovis in a multi-host System’ paper say the findings of the study, funded by the Biotechnology and Biological Sciences Research Council, Defra and the Wellcome Trust, could improve control strategies, reduce disease transmission and cut associated costs.