Salmonellosis Surge: MPI reports rising cases in New Zealand cattle
Salmonellosis is a serious disease in cattle.
MPI has placed two more properties under Restricted Place Notice, restricting the movement of animals and other risky goods on and off the farms until testing is completed.
MPI describes the move as a precaution only. Results were still pending further confirmatory tests.
MPI’s director of response Geoff Gwyn said the two new farms are a single operation: a dairy platform and its runoff, both neighbours of Van Leeuwen Dairy Group farms. The suspicious tests came only from the dairy platform.
Gywn said he was not assuming the spread, even if confirmed, came from a VLG farm.
“Investigators on the ground, through NAIT records, animal status declarations and interviews, will establish all stock movements on and off the farm back to January this year, which is the risk period we’re concerned with.
“It’s too early to say whether or not there’s any relationship with the Van Leeuwen Group other than geographical.”
Gywn said the further two properties were identified through MPI’s “very comprehensive” surveillance programme, which had now tested at least 40,000 samples of milk, blood and swabs.
“This is exactly why we are doing this testing work – to know where the disease is in order to contain and remove it,” said Gwyn.
“We do not believe the new suspect properties represent a game changer. These farms are in the same geographical area as all known infected properties and neighbour Van Leeuwen Dairy Group farms.
“Our investigators are still building a picture of how animals on the farms could have been infected, if indeed they are, and what stock movements may have taken place onto the farms.”
Mycoplasma bovis spreads through close, prolonged contact between animals and through the direct movement of stock.
“The discovery of the new potentially positive properties has not changed our position on this. We do not believe there is a significant risk of disease spread across fences,” said Gwyn.
So far only seven farms have been confirmed to have the disease -- five of them part of the Van Leeuwen Dairy Group where the disease was discovered for the first time in New Zealand in July. However, the new development brings to 22 the number of properties under Restricted Place Notices.
Last month MPI announced a decision to cull all cows from infected farms – about 4000 animals. It says the cull is “progressing steadily and to plan”.
Meanwhile, the total number of samples required is being revised upward, largely because MPI has decided to test more low-risk properties than first estimated.
Gwyn said MPI is still working to find the source of the outbreak, assuming six broad possibilities: germ plasm (semen and embryos), feed, live animals, biologicals (veterinary medicine), fomites (machinery and equipment surfaces) or other animals.
The strain is also being genotyped to help identify the likely overseas origin, and that is expected to be known by the end of November.
“My position would be that the public of NZ want us as much as possible to eradicate this disease. And just because we can’t specifically identify an entry pathway I don’t think that would change.”
Gywn said if M.bovis were found to be endemic there would be no point in culling stock but it would become a matter of management.
“But we’re not in that space. We’re quite confident it is localised.”
