The Animal Health Board (AHB) says DNA analysis has shown farmers were probably correct in thinking a controversial outbreak of bovine tuberculosis (TB) near Wairoa last year was brought into the area by infected cattle.
"The DNA 'fingerprint', along with the owner's records of stock movements and purchases, points to a cattle herd near Taumarunui as being a possible source of infection," an AHB spokesman said today.
The DNA type has not so far been found in feral wildlife, discounting the board's initial assessment that the Wairoa cases may have been caused by TB-infected wildlife.
"It now seems more likely that infection was introduced in cattle," the board said.
A wild animal survey over 2000ha on the east side of the Wairoa River was almost complete, but the 170 possums trapped so far had all returned a negative result for TB.
The outbreak in December proved controversial when local farmers criticised a big Hawke's Bay farming company, Brownrigg Agriculture, for "importing" TB into the region by transporting infected cattle.
The Gisborne region does not have endemic TB in feral animal populations such as possums, and the outbreak at Whakaki, 18km west of Wairoa, prompted a flurry of criticism from the region's farmers.
An initial outbreak on the Gisborne side of the Wairoa river was in Brownrigg's wagyu cattle at Ohuia Station in June 2004 and in September it was confirmed there were more TB-infected cattle at Ohuka.
Brownrigg Agriculture is a large Hawke's Bay-based farming company that owns and leases land all over the North Island. But a spokesman for the Animal Health Board, Terry Hynes, said yesterday that all of the health status cards for the cattle, and other documentation had been correctly completed when they were moved.
This suggested there was an animal in the mob which failed to show up in testing, but then went on to infect others. Brownrigg Agriculture chief David Brownrigg said yesterday that the cattle had received the required pre-movement TB test.
"Given the level of risk management that we have in place, it is very disappointing that infection has occurred," he said.
Hawke's Bay regional animal health committee chairman, Dan von Dadelszen, said it would be easier to deal with an isolated case of TB in livestock than it would have been to deal with wildlife infection, which was much harder to detect and control.
Mr von Dadelszen said it had been "prudent" for the AHB to act as if wildlife infection was involved.
"It is still important to continue the surveys of wild animals in the area," he said. Disease control managers considered it necessary to continue the surveys and control work.
A further 5800ha has also been targeted for possum control in March and April.
