Studies highlight past and present Salmonella outbreaks

By Joseph James Whitworth

- Last updated on GMT

Salmonella outbreaks in the last few years you may have missed
Salmonella outbreaks in the last few years you may have missed

Related tags Salmonella enterica

A number of different Salmonella outbreaks and investigations were brought to the attention of FoodQualityNews during a recent event.  

Research on them was presented at the International Symposium Salmonella and Salmonellosis (I3S) in Saint Malo, France last week.

One paper described a multi-country outbreak of Salmonella Enteritidis which has sickened more than 80 people.

S. Enteritidis PT8 infection with MLVA profile 2-9-7-3-2 was detected this year in Scotland, according to research.

Whole Genome Sequencing (WGS) identified two related but distinct clusters and confirmed 52 cases from England and Wales and, with help from the ECDC, 17 cases from the Netherlands, Finland and Denmark.

Derek Brown et al suggested the outbreak could be associated with one or more vehicles of infection or infection from a single source with two distinct strains or two or more vehicles from two different sources distributed through the same supply networks.

S. Dublin in cheese

In January this year the National Reference Centre (NRC) for Salmonella in France reported an excess of Salmonella enterica serotype Dublin (S. Dublin) infections.

The French Agency for Food, Environmental and Occupational Health and Safety (ANSES) performed Multiple-Locus Variable number tandem repeat Analysis (MLVA) subtyping to differentiate the outbreak from sporadic cases with no frequent MLVA profiles.

Editor's note

To modify a phrase used by Doug Powell of Barfblog – the leafy cone of silence – is this the Salmonella sphere of silence? Well I am not sure I would go that far but it has to raise questions on why these outbreaks are/were not put in the public sphere. I have had a good look around and the majority cannot be found, in any language (happy to be corrected!)

The industry we write about is a fiercely competitive bottom-line driven business and equally as companies should be praised when they do good things they must be held accountable when all doesn’t go to plan. We can see from what is made available that work is being done but sometimes it isn't a bad idea to engage in a bit of 'Hey, look at what we are doing or we did'.

I get that media is not the first port of call and some public health and regulatory agencies are more helpful than others when trade media comes knocking but people wonder why us journalists are a suspicious bunch? Between what is reported and the trickle through portals such as RASFF it does make you wonder what else we are missing…

The French Directorate General for Food (DGAL) used cases’ supermarket loyalty card data for traceback investigations.

Aymeric Ung et al performed a case-case study to compare food histories of outbreak cases with those of sporadic S. Dublin cases.

They interviewed 63 of the 86 cases. Cases with the main MLVA profile were more likely to have consumed Morbier cheese and those with the second MLVA subtypes were more likely to have had Vacherin Mont d’Or cheese.

Traceback investigation pointed towards several cheese manufacturers, but a single producer could not be linked to the majority of the cases.

The results suggest that more than one outbreak occurred with different raw‐milk cheeses as potential vehicles, said the researchers.

Salmonella in frozen burgers

An outbreak of Salmonella enterica serotype Enteritidis in Northern France was reported between December 2014 and April 2015.

Epidemiological investigations following the initial notification of five cases of salmonellosis (two confirmed S. Enteritidis) in young children from the Somme department revealed all cases went to the same unnamed establishment.

Frozen beef burgers from Poland were identified as the outbreak source and a suspected lot was recalled on 22 January 2015.

In early March a second notification of S. Enteritidis cases in the Somme department reinitiated investigations that confirmed a link with the same beef burgers distributed by the food pantry.

Gabrielle Jones et al said a total of 44 Salmonella cases (22 S. Enteritidis) were linked to eating beef burgers.

Microbiological analyses confirmed contamination by S. Enteritidis of beef burgers from a lot remaining in case homes and comparison of human and food strains showed the same MLVA profile.

Retrospective WGS analysis

Simon Le Hello et al described a European wide outbreak associated with exposure in Morocco which was probably a multisource outbreak with several infected food chains.

In September 2014, six European countries reported Salmonella enterica serotype Chester (S. Chester) cases to the ECDC associated with travel to Morocco. They were Belgium, France, Spain, Germany, Sweden and the UK.

Whole genome sequencing (WGS) offered the possibility to refine the strain characterization and sample comparison.

Cases of S. Chester were more likely to have ate shrimps, eaten in restaurants and visited the coast.

The results of the WGS showed 90 human and six nonhuman (from chicken sausages, poultry meat, decanted water, fish meal) isolates clustered into a tight group.

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