Salmonella Dublin is a bacterium that changes to fit its host. It is known to have a big effect on the health and productivity of infected cattle herds. Importantly, the organism has the potential to spread to other species, though this doesn’t happen very often. How an outbreak starts can be very different from one to the next.
Salmonella Dublin is a bacterium that changes to fit its host. It is known to have a big effect on the health and productivity of infected cattle herds. Importantly, the organism has the potential to spread to other species, though this doesn’t happen very often. The ways that outbreaks show up are very different, according to the Agri-Food and Biosciences Institute.
As the infection is often spread throughout the body, it can cause a wide range of diseases and symptoms, such as abortion, diarrhoea, and septicemia. People often show signs of pneumonia and meningitis. Some clinical signs, like slow growth and poor health, can last for a long time. Sloughing of the extremities is a clinical sign that happens less often but is easy to spot. Salmonella Dublin infections are more common in the fall, which suggests that they are tied to a certain time of year.
Salmonella Dublin infection is known to cause people to become carriers. Cattle that carry the bacteria may shed it all the time, sometimes, or not at all. Latent carriers can temporarily pass the bacteria in their poop, making it easy for other animals to catch the disease. This shedding often happens when latent carriers are under a lot of stress, like when they are giving birth. During times of stress, active carriers will also lose more hair.
Salmonella Dublin can be hard to control both when there is an outbreak and when an entire herd is infected. There are a number of important basic rules that should be used to control the infection. These rules also apply to other infectious diseases, especially Johne’s disease. It is important to have high standards of general hygiene and limit your exposure to faeces as much as possible. One of the most important things to take care of is the cleanliness and management of the area where calves are born.
The preweaned calves are the most likely to get sick on the farm, so they should be cared for according to the same rules as other calves. For example, they should be given the right amount of colostrum and kept in a clean area to limit their exposure to faeces. The purchase of animals is a big risk factor. To reduce risk, herd biosecurity and quarantine protocols should be looked at regularly.
Clinically sick animals should be kept completely separate from the area where calves are born. Animals can be less at risk of getting sick by using vaccinations and management programmes together. Zoonotic infections can be caught by coming into direct contact with cattle or their waste, or by drinking milk that hasn’t been pasteurised. Staff and visitors to farms need to be very clean and healthy.
Salmonella Dublin can be found in two ways: by isolating the organism itself or by looking for an antibody response to the organism in an animal. Whether a diagnosis is needed for an individual animal or for the whole herd will determine the best way to test.
Bacterial culture can be used to find the organism itself in a number of different types of samples. The most common method is called “faecal culture.” The sensitivity depends on how sick the animal is, what stage the infection is in, and if antibiotics have been given before. It can be hard to separate the organism from the more long-lasting clinical signs or from animals that have been treated.
When compared to trying to grow Salmonella Dublin in a lab, measuring antibody levels will give a more accurate picture of the status of the herd. Serological tests can be done on samples of blood or milk. Peak antibody titres happen 5 to 6 weeks after an infection, so serology is a good way to look back and diagnose or keep an eye on things.
Maternally derived antibodies can stay in the blood for up to 3 months, which can make it hard to figure out what the results mean if blood is taken from calves younger than 3 months. The Salmonella Dublin ELISA’s sensitivity and specificity change depending on the age of the animal sampled. The test works best on young cattle between the ages of 3 and 10 months, when both sensitivity and specificity are high. So, it could be used as part of the routine screening of young stock to find herd replacements that don’t have antibodies.
Bulk tank milk (BTM) Salmonella Testing for Dublin can be a helpful part of planning for herd health. The herd level sensitivity of this test is greatly improved when samples are taken every three months. For a herd to be considered to have a herd level prevalence of less than 5%, it needs to have four negative tests three months apart. This can let the herd owner and their veterinary surgeon know right away if the risk of disease is going up, so they can review hygiene and management practises and make changes right away. This test is not good for getting herds vaccinated. If most of the disease is found in the youngstock, it may be best to test both the bulk tank and calves older than 3 months using serology.
The AFBI’s Veterinary Sciences Division can help with these disease investigations by doing a variety of specialised tests. Your own veterinarian will be the best person to give you specific advice because he or she knows how healthy your herd is right now.
