Broilers are frequently infected with salmonella

One in six broiler flocks in German broiler holdings is infected with Salmonella. This is the result of a pilot study conducted by the Federal Institute for Risk Assessment (BfR) together with the competent authorities of the federal states. It was commissioned by the Federal Ministry of Food, Agriculture and Consumer Protection within the framework of an EU-wide study. The results confirm that chicken meat can be a major source of foodborne infections. If it is not sufficiently heated prior to eating, the consumer runs a high risk of contracting a Salmonella infection. Furthermore, other foods may become contaminated with Salmonella during the preparation of chicken dishes. BfR President, Professor Dr. Dr. Andreas Hensel, therefore, recommends that consumers pay very special attention to good kitchen hygiene.

For the study a total of 408 flocks in all federal states with broilers were examined between 1 October 2005 and 30 September 2006. The samples were taken in the course of the year from flocks with between 750 and 24,000 animals in line with the EU provisions. The data from 378 flocks from farms with at least 5,000 animals were evaluated.

This study is the first to offer a representative overview of the scale on which German broiler stocks are contaminated with Salmonella. A comparison with the data available up to now from other European countries show that the observed rate of 17.5 percent is comparatively high and puts Germany in the upper range. In Scandinavian countries in which Salmonella has been systematically controlled in stocks for years, the rate is considerably lower.

The surveillance authorities of the federal states involved collected a total of 1,892 samples. In the BfR National Reference Laboratory for Salmonella, the Salmonella isolated from the positive samples were serologically typed and examined further: the BfR scientists identified 18 different types of Salmonella (serovars or serotypes). The range of pathogens is thus broader than in laying hen stocks which were examined in a similar study in 2004/2005 (cf. BfR Press Release 18/2006). The serovars also included the pathogen strains S. enteritidis and S. typhimurium that are frequently detected in human salmonellosis cases in Germany albeit far less often than in laying hens.

The study also examined whether and, if so, which antibiotics the individual strains are resistant to. Some of the pathogens were not sensitive to up to 10 of the 17 antimicrobial substances examined.

The results of the study will be passed on to the European Food Safety Authority, EFSA, for evaluation along with data from other EU Member States. The goal is to develop a joint European strategy to control zoonotic agents and, more particularly, Salmonella in poultry flocks.

In order to reduce the risk to consumers of Salmonella infection from poultry meat, the next step will be concerted action to markedly reduce the Salmonella contamination of broiler stocks. As all salmonella serovars can, in principle, be transmitted to humans and trigger disease, this strategy must cover all types of pathogen and should not be restricted to the ones most frequently detected in humans: S. enteritidis and S. typhimurium. Steps to prevent the infection of animals during breeding, fattening and transport to the slaughterhouse are very important. Action must equally be taken to avoid the contamination of Salmonella-free carcasses with Salmonella during slaughter. Furthermore, attention must be given to the production, packaging and distribution of poultry meat products so as to prevent recontamination during their journey to consumers.

Consumers can easily and effectively protect themselves from Salmonella infection by thoroughly heating poultry meat prior to consumption and preparing it away from other foods that are not going to be heated. The Frequently Asked Questions section on the hygienic handling of poultry meat on the BfR website contains additional information.

The report “Fundamental study on determining the prevalence of Salmonella in Gallus gallus broiler stocks” (in German) can be accessed under “Mikrobielle Risiken/Zoonosenforschung” on the BfR website.