Week 38: Salmonella May Remain After Cleaning
A new study shows that Salmonella can remain both inside and around poultry houses after cleaning and disinfection. In particular, the surrounding farm environment may act as a reservoir and reintroduce the bacteria into cleaned facilities.
How was the study conducted?
Researchers analysed 1,200 environmental samples from 21 German broiler farms where Salmonella had previously been detected. The samples were collected after the poultry houses had been cleaned and disinfected. Both areas inside the houses and the surrounding farm environment were examined.
What did the study find?
Salmonella was detected in 27.6% of the samples despite cleaning and disinfection. The bacteria were found more frequently outside the poultry houses than inside them: 34.5% compared with 25.1% of the samples.
Salmonella was detected in ventilation systems, cracks, water-related equipment, walkways and other hard-to-reach areas. The highest proportion of positive samples was recorded during autumn.
What is new?
The study clearly shows that the surrounding farm environment can act as a reservoir of infection and reintroduce Salmonella into a cleaned poultry house. Cleaning the poultry house alone may therefore not always be enough.
Strength of evidence
Moderate. The study included a large number of samples collected from real farm environments, but only farms with previous Salmonella problems were included. Sampling locations were also selected partly because of visible dirt and suspected risk areas. The figure of 27.6% therefore does not show how common Salmonella is across all poultry farms.
What does this mean for backyard flocks?
The findings reinforce the importance of cleaning equipment, footwear, transport crates, water containers and the area surrounding the poultry house. Organic material, dust and dirt should be removed before disinfection because disinfectants are less effective on dirty surfaces. Cracks and other hard-to-reach areas should also be included in the cleaning routine.
However, the study does not show that Salmonella is highly prevalent in ordinary backyard flocks.
