Salmonella presence on European pig farms

The BIOPIGEE project (‘Biosecurity practices for pig farming across Europe’) was designed to study the effectiveness of biosecurity measures for the control of two important zoonotic pig pathogens: Salmonella and hepatitis E virus (HEV). To study this, 30 pig farms were to be enrolled from each of seven European countries (AT, BG, CZ, DE, PL, IT, UK) to collect biosecurity information and samples to determine the farms’ risk status for these two pathogens. This study describes the data collected on Salmonella presence.

Farm types included were: fattening; breeding; and farrow-to-finish units. Small holdings, nucleus/ multiplier units and Specific Pathogen Free (SPF) herds were excluded. From each farm, 20 pooled floor faeces samples were collected; with 10 pools collected per sample. Samples were collected from the floor of gilt, dry sow and finisher enclosures, selected to be representative of the farm’s population. Samples were tested for Salmonella using traditional bacteriology methods in accordance with ISO 6579-1:2017.

In total, 199 farms were sampled (18-33 per country) from January 2020 to November 2021 and Salmonella was detected from 69 farms (34.7%), with 1-18 positive samples per positive farm (305 in total). The average percentage of positive samples was 7.6% in total, and 21.9% on the positive farms. The 57 fattener farms had an average of 9.3% samples positive and 36.8% farms were positive; 40 breeding farms also had an average of 9.3% samples positive (42.5% farms positive); 102 farrow-to-finish farms had an average of 5.9% samples positive (30.4% farms positive).

Serovar results were provided from 297 samples and 23 different serovars were detected, with 1-3 serovars detected per positive farm. The most common serovars were S. Derby, monophasic S. Typhimurium (mST) and S. Infantis (98, 85 and 31 isolates respectively). Five other serovars had 6-26 isolates detected and the remaining 15 serovars were detected in five or fewer isolates. S. Derby and monophasic S. Typhimurium were the most commonly detected in most countries (both by number of samples and number of farms). However, from the Bulgarian farms, S. Infantis was the most common and in Austria, only two farms were positive and these had different serovars: S. Infantis and S. Montevideo. These results indicate the difference in Salmonella presence within European pig farms and between farm types.

This work was supported by funding from the European Union’s Horizon2020 Research and Innovation programme under grant agreement 773830: One Health European Joint Programme.