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Salmonella Brandenburg Frequently Asked Questions

What is Salmonella Brandenburg?

Salmonella Brandenburg (S. Brandenburg) is a member of the Salmonella family of bacteria. Like most Salmonella, it lives in the intestines of animals and people, and is generally spread by contact with a contaminated environment, faecal contamination in food and water, contact with animals and from person to person.

While Salmonella is a leading cause of foodborne illness in New Zealand, until recently the S. Brandenburg strain was an infrequent cause of human illness in New Zealand. Though relatively common overseas, it had rarely been isolated in farm animals in New Zealand.

What’s new about this bug?

In 1996, a subtype of S. Brandenburg, now known as the ‘South Island strain’ was identified as the cause of abortions in sheep in mid Canterbury. Stock movements that year, due to drought introduced the organism to South Otago and it rapidly spread to epidemic proportions in South Otago and Southland. Since then, the South Island strain of S. Brandenburg has also been associated with diarrhoea in cattle and calves.

The South Island strain has not been associated with sheep infections north of mid-Canterbury and in the North Island, although it has been isolated in the North Island in a single pig and occasionally in poultry feed.

Can people get S. Brandenburg?

Prior to 1996, human cases of S. Brandenburg were reported infrequently and sporadically. However, human cases increased with the southern sheep epidemic, with a peak occurring in 2000. This peak coincided with the peak in confirmed cases of sheep abortions due to S. Brandenburg on South Island farms.

The majority of the human cases have been attributed to contact with infected farm animals, and have included veterinarians, veterinary workers, sheep and cattle farmers, farm workers, and slink skin handlers. The greatest risk is for children exposed to calf rearing and lambing operations, with bobby calves posing the most significant risk.

What are the symptoms?

Like all Salmonella, S. Brandenburg can cause the disease known as ‘Salmonellosis’, a gastrointestinal illness. In humans, typical symptoms include diarrhoea, nausea, vomiting, low grade fever and headache.

Symptoms may be more severe for at risk groups including the young, the old, pregnant women and people with weak immune systems. In extreme cases, Salmonella can cause stillbirth. However there are no indications that S. Brandenburg has caused stillbirth or abortion in pregnant women.

Severe symptoms, (meningitis, osteomyelitis and mono arthritis in the hip) associated with the South Island strain of S. Brandenburg, have recently been reported in three children between six months and eight years. It is not known if this represents an increase in virulence of the strain or reflects the increased incidence of the disease in bobby calves, and exposure to very high numbers of Salmonella through contact with bobby calves.

What about animals?

Like most Salmonella, S. Brandenburg lives in the intestines of animals especially pigs although prior to 1996 had rarely been isolated from New Zealand farm animals.

The South Island strain of S. Brandenburg has most frequently been detected in adult sheep where it causes abortion. Recently, the South Island strain of S. Brandenburg has been associated with diarrhoea in cattle and bobby calves.

Domestic animals such as dogs and horses are susceptible to S. Brandenburg. There has been one reported case of stillborn pups in a dog. Recent research indicates lambs may not be susceptible to S Brandenburg infection, as they do not exhibit symptoms if animal salmonellosis.

Contact with farm animals and contaminated environments are major sources of risk on the farm. Children who come into close contact with bobby calves are especially at risk.

Does food transmit S. Brandenburg?

Salmonella is historically recognized as being transmitted by eating infected food, such as undercooked meat, poultry or eggs. To date, however, there is no indication that this plays a significant role in spreading the South Island strain of S. Brandenburg.

No cases have been reported as foodborne, and a recent NZFSA commissioned study could not ascribe a single case to the consumption of food. All cases were associated with farms and/or animal contact.

What can be done to control it?

For prevention people should:

• wash hands regularly, particularly after contact with farm animals or equipment
• change clothes immediately after contact with farm animals or equipment
• avoid smoking on infected farms
• clean farming equipment, for example sheering equipment after use

For on farm prevention, veterinarians can:

• recommend management techniques (including nutrition, stocking and handling) to prevent the disease
• provide guidelines in the event of an outbreak
• recommend precautions to prevent an outbreak spreading further
• vaccinate animals

As always good food handling practice and food safety guidelines should be followed.

What is the NZFSA doing?

The NZFSA is co-ordinating a 3 year project to:

• identify the optimal points in the food chain for the control of Salmonella species in sheep meat, and Salmonella Brandenburg in particular
• investigate on farm experience and develop in consultation with farmer groups programmes to reduce animal health losses and human exposure
• investigate and develop other short-term risk management strategies.
• monitor trends of S Brandenburg bacteria through the National Microbiological Database

How can I find out more about this?

For more information please contact:

Roger Cook,
Programme Manager (Microbiology)
NZFSA,
86 Jervois Quay,
PO Box 2835,
Wellington.

Email Roger.Cook@nzfsa.govt.nz