The trial, which was conducted by a UK-French team of researchers from PBD Biotech and Biosellal, is being presented at the European Association of Veterinary Laboratory Diagnosticians (EAVLD) Congress in Brussels today.
Current tests only allow the reliable detection of Mycobacterium avium subspecies paratuberculosis (MAP) from 18-24 month calves and are unable to distinguish between active and passive infection.
For the 16-month trial, calves from three different herds and born from MAP-positive and MAP-negative cows were tested monthly using PBD Biotech’s Actiphage Rapid kit and Biosellal’s Bio-T kit MAP PCR on blood samples, and the same PCR on faeces.
Researchers say the trial proves that early detection of live MAP infection is possible, and paves the way for improved Johne’s disease monitoring and control measures on farms.
Co-Author Dr Ben Swift, Research Fellow in Antimicrobial Resistance at the Royal Veterinary College and R&D Director at PBD Biotech, said: "Young animals are highly susceptible to infection and being able to identify Johne’s disease at this early stage is key to controlling disease spread.
The trial showed that the sensitivity and specificity of Actiphage enables detection of lower levels of MAP than the current culture methods, and provides results in 6 hours rather than weeks."
The Actiphage Rapid technology used in the trial identified live MAP infection at least 4 weeks’ earlier than the faecal PCR in 75% of cases: in one case, the new diagnostic detected MAP in the blood of a one-day old calf born from a MAP-positive cow.
Claire Pelletier, Directrice Générale of BioDev, consultant to Biosellal, will be presenting findings from the trial, which also showed the transient nature of the infection. She said: "The study showed that two calves, identified as MAP-positive by Actiphage-PCR on blood during the first monthly sampling didn’t shed MAP into their faeces until 10 and 11 months. This emphasises that early detection provides a short window of time that allow for control of the disease."
Other international trials using Actiphage are underway to investigate the presence of MAP in milk.
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