ISSUE FOCUS 36 FEED & ADDITIVE MAGAZINE June 2025 a water activity (Aw) of at least 0.94. If the pH is less than 4.5, and the Aw is less than 0.94, growth becomes difficult. This is also why, in poultry, if Salmonella is present, you will find it more in the ceca (higher pH and higher Aw). Understanding its reservoirs and transmission routes is essential to developing a strategy to control Salmonella contamination in poultry and to reduce the risk of Salmonellosis. Poultry harboring the bacterium without any symptoms is the biggest risk to food safety. One animal that’s positive in a flock can have a significant impact on the spread of Salmonella within the flock, due to increased shedding in the feces during stressful circumstances such as overcrowding, catching, and transportation. Salmonella cells can survive freezing, or even drying, without losing their ability to become pathogenic. Salmonella can survive even in an environment rich in salt. Like the increased risk of mycotoxins being present in cereals due to climate change, Salmonella can be present for the same reason. Higher temperatures and increased precipitation help Salmonella survive and multiply faster in nature. As Salmonella is part of the process maintaining ecological balance, the most common natural reservoirs from which it all starts are the water sources and the soil. Salmonella bacteria have the ability to create a biofilm to protect themselves against harsh circumstances or antibacterial products – but they also have other mechanisms to survive and compete with other microorganisms for the necessary nutrients or to move to better locations for survival, growth and multiplication (e.g., virulence factor and invasiveness). Figure 1 shows the direct and indirect Salmonella transmission routes between animals and humans, as well as the mechanisms to survive, grow and multiply in both human and animal bodies. Reducing the risk of Salmonellosis entails interrupting these transmission routes, either by improving biosecurity processes ((personal) hygiene, cleaning, disinfection, bird- and rodent-free housing, no pets, etc.) or by reducing the shedding of Salmonella (by which the soil or water can become contaminated, creating a vicious circle of contamination, cross-contamination, and re-contamination). HOW TO REDUCE THE RISK OF SALMONELLA CONTAMINATION This article does not present biosecurity measures that can be taken to reduce the risk of Salmonella entering the poultry production chain; instead, we briefly outline a strategy by which you can reduce the risk of Salmonella in poultry by focusing on the animal itself and by focusing on Salmonella behavior in the animal. Figure 1. Transmission cycle of Salmonella between animals and humans
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