Salmonella Dublin (S. Dublin) is an emerging threat in all cattle sectors across Canada. As well as causing sickness and death in calves, S. Dublin is transmissible to people. The strains currently circulating are broadly antibiotic-resistant, making heightened biosecurity measures crucial.
S. Dublin has been found on dairy and veal farms across Ontario and has been responsible for high levels of mortality and disease when outbreaks occur (Figure 1).
What symptoms does S. Dublin cause?
The most obvious sign that S. Dublin is present is very sudden death with no other clinical signs or respiratory disease that does not respond to treatment. These signs in individual animals are commonly accompanied by a sudden outbreak in an entire group of calves, with high levels of mortality.
The other major manifestation of S. Dublin is one that cannot be seen, where animals appear completely healthy but are shedding the bacteria in their manure and milk. These “carrier” animals are the ones responsible for spreading the bacteria between and within farms.
S. Dublin is commonly resistant to a number of antimicrobials making it very difficult to treat. This leads to very poor response to therapy and highlights that a focus should be placed on preventing contact with this bacterium.
S. Dublin is a zoonotic disease, meaning the bacterium can infect animals and people. In humans, it can cause very severe disease, including septicemia, and may require long-term hospitalization. Due to the zoonotic risk, only consuming pasteurized milk, wearing gloves, and thorough hand washing when working with animals is best practice to prevent infection.
Efforts should be made to prevent the entry of the bacteria onto farms. Practicing a high level of biosecurity is critical to prevent an infected animal or a visitor with S. Dublin on their boots or clothing onto the farm. When farms are infected with S. Dublin, it is possible to eliminate the disease by cleaning and disinfecting and using specific management practices.
To best control this disease on-farm, focus on stopping the transmission to and between young calves, and lowering the levels of the bacteria in the environment. This can be accomplished by evaluating management of the calving pen and youngstock as well as having excellent cleaning and disinfection protocols. In addition, avoiding the purchase of additional infected animals is also important to lower the amount of the bacteria in the environment.
Housing, feeding equipment, and other surfaces that come into frequent contact with manure are critical control points that, when cleaned and disinfected, will reduce transmission of this bacteria. It is important to clean and disinfect as S. Dublin has a tendency to persist in dairy and veal herds due to the environmental survival of the bacteria. Specifically, it is able to survive for months in cattle manure and soil, and for years in dried feces. It is also able to multiply in the environment under warm and moist conditions. Therefore, cleaning all of the surfaces that calves may come in contact with is important to eliminate the spread of this pathogen. Specifically, the calving area, livestock trailers, calf pens, and feeding equipment should be the main targets for cleaning and disinfection. Using oxidizing agents, such as accelerated hydrogen peroxide or chlorine dioxide, after fecal matter has been removed will kill S. Dublin.
S. Dublin is an emerging pathogen that can cause high levels of mortality and respiratory disease that does not respond to treatment. Diagnosis of acutely affected animals is often achieved through post-mortem examination, whereas carrier animals require repeated blood tests to diagnose their status. Producers should work with their veterinarian to prevent or reduce the occurrence of S. Dublin in their herds.
Salmonella Dublin | An emerging disease in Ontario
The Healthy Calf Podcast Series focuses on taking a proactive approach to reduce disease and improve performance.
Learn more about preventing, identifying, and controlling Salmonella Dublin on your farm in this Podcast with Dr. Cynthia Miltenburg, lead veterinarian in the Animal Health and Welfare Branch of the Ontario Ministry of Agriculture, Food, and Rural Affairs.