According to the latest EFSA report, salmonellosis is the number two bacterial zoonosis in Europe (Zoonoses Report 2018) Read Online.
Therefore, the poultry industry has a special responsibility to prevent the introduction of salmonella into the flocks and thus minimise the risk of transmission to humans.
Salmonella bongori is mainly found in reptiles. In warm-blooded animals, such as mammals and birds, Salmonella enterica is primarily found. Eight subspecies are distinguished, whereby almost all infections in birds and mammals are caused by the subspecies Salmonella enterica subsp. enterica.
While the host-specific serovars S. Gallinarum Biovar Pullorum (Pullorum disease) and S. Gallinarum Biovar Gallinarum (Fowl typhoid) can lead to severe clinical symptoms and sometimes high losses in chickens, non-host-specific salmonella serovars are primarily of great food hygiene and economic importance as causative agents of zoonoses.
These include S. Enteritidis, S. Typhimurium, S. Virchow, S. Hadar and S. Infantis. These only rarely cause clinical illness in poultry, but trigger the majority of salmonelloses in humans.
The above-mentioned non-host-specific salmonella serovars very rarely cause clinical symptoms such as diarrhoea or reduced performance in adult chickens.
In very young chicks, however, high losses and a chronic disease with joint swelling and respiratory problems may occur. Pathological examination may reveal inflammatory alterations of the navel, heart, appendix and liver.
In addition, animals that survive such an early infection are considered lifelong salmonella shedders.
Depending on flock management, age and breed, losses of up to 100% may occur (see Table 2). White hybrid lines are less affected than brown lines.
Suitable samples for the direct detection of salmonella are:
- Organ samples
Consequently, indirect detection via antibodies is only useful if the tested flock has not been vaccinated against the serovar to be tested.
Such screenings are therefore mainly carried out for S. Pullorum and S. Gallinarum. However, the results can be influenced in particular by the use of inactivated S. Enteritidis vaccines.
Parent animals can no longer be used for the production of chicks, eggs from laying hens may no longer be sold as grade A and the meat of salmonella-positive animals must be heat-treated after slaughter (national legislation must be considered!).
Non-living vectors such as equipment, clothing, egg crates and bedding must also be critically considered.
The production process should guarantee freedom from salmonella and care should be taken during storage to ensure that rodents and insects cannot contribute to contamination.
Professional rodent and pest control can help minimise the risk.
Furthermore, it is possible to boost immunity with inactivated vaccines.
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