Clock ticking for Johne’s

By Samantha Tennent

Johne’s disease costs the New Zealand dairy industry millions of dollars in production but a new test may help farmers detect it earlier.

Johne’s disease is a complex disease that can be hard to spot but an Auckland-based diagnostic company, Pictor, has been developing a test that could change the way it is detected and managed on farm.

Pictor commercial operations director, Andrew Charles, is excited about what this could mean for farmers when it comes to improving the health and productivity of their herds.

“The diagnostic testing currently used in New Zealand for Johne’s, BVD and other diseases, is normally based on single selected antigens that get broad responses from animals,” Charles said.

“But we have found a way to use a number of different antigens within a single test, allowing the disease to be detected a lot earlier, as opposed to the existing tests that routinely only detect the disease one to two years after the animal has been infected.”

Pictor has utilised knowledge from a range of universities around the world to identify a number of antigens that can detect antibodies throughout the different stages of a Johne’s disease infection. They are able to use multiple antigens with an approach called multiplexing, which enables them to print up to nine different proteins within a single testing well. The test can use milk or serum taken from blood samples from farms and processed within an animal health laboratory.

“A more sensitive test that will be able to determine the earlier versus later stages of infection has the potential to change the course of Johne’s disease management,” Charles said.

“Typically, cows detected with Johne’s disease are culled to reduce the chances of transmitting it to other cows but by that point they are often already shedding the disease and infecting other animals.

“If farmers can find out earlier if a cow carries the disease before she starts shedding and showing clinical signs, they can track the infection and manage cows accordingly while reducing the risk to the rest of their animals.”

Johne’s disease is estimated to cost New Zealand as much as $88 million in lost production each year and is mostly transmitted through infected faeces. It can also be passed on to calves through colostrum – and knowing which cows are infected can prevent their colostrum from being used.

The test is in the late stages of development and has been supported by the Ministry for Primary Industries’ (MPI) Sustainable Food & Fibre Futures fund. Pictor hopes to launch it in the next few months and farmers will be able to access it through their veterinarians.

The idea evolved from conversations Pictor had with LIC, originally to test for Johne’s in conjunction with pregnancy. That type of test proved difficult, but