WHAT IS SALMONELLA?

• Bacteria that live inside carrier animals (this is the main source of spread of Salmonella in New Zealand)
• Can survive in the environment for weeks to months
• Can infect all kinds of animals including humans (zoonotic disease)
• Many different strains, two most prevalent in sheep:
  • Hindmarsh (primarily affects the gut)
  • Brandenburg (primarily causes abortions)
• All types of Salmonella can cause outbreaks and deaths
• Once Salmonella is established in a flock, it cannot practically be eliminated

TYPES OF SALMONELLA IN NEW ZEALAND SHEEP 

Salmonella Hindmarsh (gut-affecting)

• Has been in New Zealand since at least the late 1940’s
• Sudden death is often the first sign of an outbreak
• Outbreaks tend to occur in times of stress and deaths may continue sporadically for months
• Seasonal disease, occurring from late summer through early winter (most often over mating)
• Outbreaks most commonly seen in intensively managed and well-fed flocks
• Case rates and mortality varies with flock immunity (average approximately 1% mortality) may accumulate to significant numbers
• Occurs nationwide

Salmonella Brandenburg (abortive)

• First outbreaks recorded in 1996
• Causes late term abortions, sickness and death
• Occurs in late pregnancy (early spring)
• Outbreaks are sudden and escalate quickly
• Up to 15% can abort and up to 50% of aborting ewes can die
• As of 2021 only seen in the South Island

SALMONELLA VACCINATION

• Salvexin®+B is the only Salmonella vaccination for cattle and sheep in New Zealand
• It contains four strains of Salmonella: Hindmarsh, Brandenburg, Typhimurium and Bovismorbificans
• For preventative vaccination give two shots in the first year (sensitiser & booster at least 4 weeks apart), 2nd shot should be at least 2-3 weeks before the risk period
• Annual booster is required for ongoing protection
• In the face of an outbreak:
  • Hindmarsh / Gut-affecting: Vaccination should be as early as possible to reduce stock losses
  • Brandenburg / Abortive: Vaccination is not recommended in the face of a Brandenburg outbreak unless advised by your vet
• The most practical time to vaccinate for sheep farmers
  • Gut-affecting: between weaning and mating
  • Abortive: between rams in/out and scanning

MANAGEMENT PRACTICES TO MINIMISE SALMONELLA RISK

• Reduce stress (gradually introduce diet changes, lower stocking densities)
• Manage birds and pests to keep them from spreading Salmonella
• The most common way Salmonella is introduced to a farm is through healthy looking carrier animals (cattle, sheep etc.). Higher risk practices include:
  • Off-farm grazing
  • Intensive feeding
  • Purchasing/leasing stock
  • Shared boundaries/stock yards
• Farms at risk of Salmonella should consider preventative vaccination

MANAGING AN OUTBREAK

• Practice strict biosecurity between affected mobs and other groups of sheep on the property
• Involve your vet to take samples and confirm the diagnosis
• Isolate sick animals/flocks
• Monitor at-risk groups closely
• Treating individual sick animals is not usually practical
• Use strict hygiene practices when handling sick animals or working in their environment
• Prevent vulnerable (old, young, pregnant or sick) people from having contact with animals and their environment
• Use disinfectant and wear gloves, overalls and gumboots when handling at-risk animals
• Contain and/or destroy contaminated material e.g. limit sick animal movement and bury foetuses, placenta and carcasses as soon as possible
• For gut-affecting disease vaccinate all stock with Salvexin®+B as soon as possible under veterinary guidance (ensure a sensitiser & booster is given to previously unvaccinated animals and an annual booster given to all other animals)
• For abortive form, spread sheep out and consider a preventative vaccination programme next year.

Don’t wait for Salmonellosis to strike.

Vaccination reduces the impact of an outbreak and minimises production losses. Protect your flock with Salvexin®+B

REFERENCES

1. ACVM. (2018). A007886 Salvexin+B Leaflet. https://eatsafe.nzfsa.govt.nz/web/public/acvm-register
2. Baker et al. (2007). A recurring Salmonellosis epidemic in New Zealand linked to contact with sheep. Epidemiol Infect. 135:1. 76-83.
3. Clark et al. (2004). Salmonella Brandenburg—emergence of a new strain affecting stock and humans in the South Island of New Zealand. NZVJ. 52:1. 26-36.
4. Clark et al. (2002). Salmonella in animals in New Zealand: the past into the future. NZVJ. 50:3. 57- 60.
5. Daly, S. (2019). Salmonella Brandenburg on Canterbury dairy farms. Proceedings of the Society of Dairy Cattle Veterinarians of the NZVA. 29-30.
6. Gruenberg, W. (2019). Overview of Salmonellosis. Merck Veterinary Manual Online. https://www.merckvetmanual.com/digestive-system/salmonellosis/overview-of-salmonellosis
7. Li, H., et al. (2005). Vaccination of pregnant ewes against infection with Salmonella Brandenburg. New Zealand Veterinary Journal. 53:6. 416-422.
8. McGuirk, SM. & Peek, S. (2003). Salmonellosis in cattle: a review. Proceedings of the 36th Annual Conference of the American Association of Bovine Practitioners, Columbus Ohio.
9. West, DM et al. (2009). Salmonellosis. The Sheep: Health, disease and production—3rd Edition. NZVA press. 322-327.

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