Gore VetSouth veterinarian Joel Hughes said he and other vets were ''mapping'' cases around West Otago and Southland, nearly 40 farms having reported salmonella.
''It's certainly an outbreak.''
He estimated several hundred sheep, mainly ewes, had been killed by the disease.
The first cases were reported at Waikoikoi, and the disease had spread to Heriot, Waikaka and Waipahi and had almost reached Wyndham.
Farmers were advised to vaccinate sheep and, after vaccination, deaths usually stopped between seven and 10 days later. Two shots provided the best protection, he said.
There was an antibiotic available to treat infected livestock, but the disease was fast acting and stock usually died in 12 to 24 hours.
''Vaccination is the best thing for stopping the spread of salmonella.''
There was a huge demand for the vaccine, and clinics were struggling to stock enough to meet demand, Mr Hughes said.
''We're getting plenty from the supplier, but it's just flying off the shelves.''
The spread of salmonella seemed to be slower in South Otago, veterinarian John Smart, of Clutha Vets, saying he knew of about 10 farms around Balclutha and one near Milton that had been affected.
Cases among sheep had seemed to peak in the past three weeks, and most South Otago cases were now in the area between Balclutha and Clinton, he said.
Salmonella hindmarsh is a bacterial disease that leads to inflammation of the intestines and spreads into the bloodstream, killing animals quickly.
The disease tends to strike ewes and two-tooths and not older hoggets.
It is spread by carrier animals and excreted on to grass and can survive in soil, water, faecal material and animal feeds.
Mr Hughes said people, vehicles and gumboots could also spread salmonella.
Otago Federated Farmers president Stephen Korteweg said it was important to practise good hygiene for the health of both humans and stock.
Recommendations
To reduce chances of human infection. -
1. Use disposable gloves when handling any aborted material or lambing any suspect ewe. These are available at all vet clinics.
2. Avoid putting fingers, dog whistles etc anywhere near your mouth until washed in disinfectant.
3. Wash hands in disinfectant before every meal.
4. Do not bring contaminated clothing/footwear indoors.
5. Clean and disinfect boots.
6. Do not smoke (at least until your hands are clean).
7. Take care young children are not exposed to potentially contaminated material.
SOURCE: Beef + Lamb New Zealand
