An outbreak of Salmonella Typhimurium infections in Denmark, Norway and Sweden, 2008.

In November-December 2008, Norway and Denmark independently identified outbreaks of Salmonella Typhimurium infections characterised in the multiple-locus variable number of tandem repeats analysis (MLVA) by a distinct profile. Outbreak investigations were initiated independently in the two countries. In Denmark, a total of 37 cases were identified, and multiple findings of the outbreak strain in pork and pigs within the same supply chain led to the identification of pork in various forms as the source. In Norway, ten cases were identified, and the outbreak investigation quickly indicated meat bought in Sweden as the probable source and the Swedish authorities were alerted. Investigations in Sweden identified four human cases and two isolates from minced meat with the distinct profile. Subsequent trace-back of the meat showed that it most likely originated from Denmark. Through international alert from Norway on 19 December, it became clear that the Danish and Norwegian outbreak strains were identical and, later on, that the source of the outbreaks in all three countries could be traced back to Danish pork. MLVA was instrumental in linking the outbreaks in the different countries and tracing the source. This outbreak illustrates that good international communication channels, early alerting mechanisms, inter-sectoral collaboration between public health and food safety authorities and harmonised molecular typing tools are important for effective identification and management of cross-border outbreaks. Differences in legal requirements for food safety in neighbouring countries may be a challenge in terms of communication with consumers in areas where cross-border shopping is common.

Composting of cattle and pig manure.

Studies of solid manure treatment on 83 Swedish dairy farms showed that no composting process occurred in the majority of cases while high temperatures could be found in the manure in 27 of 34 piglet producing farms. It was found that at least 2.5 kg of straw per cow and day must be used to get a manure that can be composted without forced aeration or turning of the material. It was also found that the straw should be given as bedding.

Survival of Salmonellas in composted and not composted solid animal manure.

Survival of S. dublin, S. senftenberg and S. typhimurium in composted cattle manure was less than seven days. In cold cattle manures S. dublin survived 183 days but not 190, while S. senftenberg and S. typhimurium survived 204 but not 214 days. In composted sow manure S. senftenberg and S. typhimurium survived less than seven days while S. derby survived 14 days but not 21.