Salmonella, Salmonella, the hidden danger for a the hidden danger for a

planet with a future planet with a future population of 9 billion.population of 9 billion.

Meeting the zero standard in Meeting the zero standard in pig meat with strategies for pig meat with strategies for

controlling Salmonellacontrolling Salmonella..

Catharina Berge, DVM, MPVM, PhD

Berge Veterinary Consulting

Salmonella – Global health Salmonella – Global health challengechallenge

• Salmonella infection from food is one of the major causes of human illness and responsible for substantial economic losses worldwide.

• Every year: Millions of people infected with Salmonella by food and thousands die from the disease.

• US- annual costs of human Salmonella infections estimated at $ 2.3 billion.

How much human How much human salmonellosis from pork?salmonellosis from pork?

• 10-20% of human salmonellosis in EU from pigs and pig meat

• 6-9% of human foodborne salmonellosis in USA from pigs and pig meat

• In Denmark, pork and pork products were reported to be responsible for 10-15% of the total Salmonella infections.

• Differences between countries due to; – the Salmonella occurrence in pigs and pig meat,– consumption patterns & preferences – relative importance of other Salmonella sources.

SalmonellaSalmonella, not tolerated by , not tolerated by consumersconsumers

• Consumers are demanding food safety assurances, not only during slaughter, processing, and preparation, but also at the farm level.

Who has the responsibility?Who has the responsibility?• a farm-to-fork approach. • the responsibility for the production

of safe food lies with the primary animal producer up through the food chain to the consumer

Strategies and lessons Strategies and lessons learnt from Europelearnt from Europe

• Experience from Denmark• European Food Safety Risk

Assessment• Tools to fight Salmonella• Benefits in Salmonella control

European Union study in European Union study in slaughter pigsslaughter pigs

• 10.3 % Salmonella-positive slaughter pigs. Varied from 0% to 29% between EU countries.

• From 9 countries level the prevalence of slaughter pigs with antibodies against Salmonella ranged from 3.5% to 33.3%.

• The top serotypes: Typhimurium, Derby, Rissen, S. 4,[5],12:i:- and Enteritidis.

EFSA-Quantitative microbial EFSA-Quantitative microbial risk assessment (QMRA)risk assessment (QMRA)

• Salmonella-free breeders,• Salmonella-free feed, • Cleaning and disinfection of holdings,• Avoiding contamination at slaughter,• Decontamination of carcasses.

Farm to consumption QMRAFarm to consumption QMRA

Transmission

Cross-contamination

Amplification

Inactivation

QMRA-Hazard and risk QMRA-Hazard and risk characterizationcharacterization

Reduced Reduced SalmonellaSalmonella in pigs in pigs arriving at slaughterarriving at slaughter

• by ensuring breeder pigs are Salmonella-free;– 70-80% reduction in high prevalence areas– 10-20% in low prevalence areas can be foreseen;

• by feeding only Salmonella-free feedstuffs;– 10-20% reduction in high prevalence areas– 60-70% in low prevalence areas

• by preventing infection from external sources of Salmonella (i.e. rodents and birds) – 10-20% reduction in slaughter pig lymph node

prevalence can be foreseen.

Breeder pigsBreeder pigs• Ensuring that breeder pigs are Salmonella-

free is the first step in high prevalence countries.

• Control measures proposed:– (1) control in nucleus and multiplier herds– (2) incoming pigs (Salmonella status) – (3) control of feed – (4) biosecurity programs incl. Salmonella.

Slaughter pigsSlaughter pigs• Control: • Salmonella-infected breeder pig

herds,• Salmonella-contaminated feed.

Slaughter house proceduresSlaughter house procedures• Slaughter house interventions are more

likely to produce greater and more reliable reductions in human illness, at least in a shorter time frame, than can be achieved at the farm in high prevalence countries.

• Countries can achieve more effective reductions in human cases by targeting both farm and slaughter house.

Effect on human Effect on human Salmonellosis casesSalmonellosis cases

• a reduction of two logs (99%) of Salmonella numbers on contaminated carcasses would result in a 60-80% reduction of the number of human salmonellosis cases attributable to pig meat consumption.

Salmonella dynamics during Salmonella dynamics during slaughter of pigsslaughter of pigs

• Salmonella increases during transport and lairage, where it reaches its maximum at kill.

• Salmonella prevalence is reduced due to singeing,

• Increases because of polishing, evisceration, and veterinary inspection.

Alban, L., Stärk, K.D.C., Prev. Vet. Med. 2005:68: 63-79.

Slaughter house hygienic Slaughter house hygienic measuresmeasures

• a high temperature at singeing, • enclosing the anus and rectum in a

plastic bag, • and improved disinfection of tools

Hot water decontamination Hot water decontamination (HWD)(HWD)

• pig carcasses are showered with 80C (176F) hot water for 14-16 seconds directly after slaughter.

• 2-log (100-fold) reduction of E. coli and Salmonella.

• New method: a combination of steam and ultrasound.

• Economic analyses have shown that steam ultrasound is the most cost-effective intervention followed by HWD.

Jensen, T. Christensen, H. Decontamination of pig carcasses with hot water. Proceedings 4th international symposium …(Safepork). 2001. Leipzig, Germany.

Lawson L.G., et al. Int J Food Microbiol 2009:134: 126-132.

Hot water decontaminationHot water decontamination

Photo from Danish Meat Research Institute

Denmark Denmark Cost Benefit AnalysisCost Benefit Analysis

• Identified the economical efficiency of a range of possible strategies.

• None of the pre-harvest initiatives investigated resulted in a substantial reduction of the prevalence.

• Only hot water decontamination turned out to be economically efficient.

Goldbach, S.G., Alban, L., Prev. Vet. Med. 2006: 77: 1-14.

How much contaminated How much contaminated feed is there really?feed is there really?

• 15% of all protein-meal imported to Sweden is detected Salmonella contaminated – soybean meal. – rapeseed meal, corn

gluten meal, fishmeal, meat meal

SalmonellaSalmonella contamination in contamination in feed millsfeed mills

• Contaminated raw products• Inappropriate heat treatment during

pelleting, • Condensation of free water in coolers,

transportation systems or storage bins of the feed mill due to insufficient cooling of the feed are important risk factors.

• Recontamination of feed after heat treatment during storage and treatment- poor cleaning, foot traffic, rodents, accumulation of wet material

Problem with Problem with sampling feed sampling feed

for for SalmonellaSalmonella

• Sampling of feed ingredients and finished feed is relatively insensitive– large volume of feed to be sampled– Difficulty in getting representative sample

• the actual occurrence of Salmonella is likely much higher than detected

What feed intervention What feed intervention strategies are available?strategies are available?

• Heat treatment• Organic acids• Physical characteristics• Probiotics

– Competitive Exclusion

• Glycans • Medium chain fatty acids• Essential oils• Prebiotics

Direct interactionDirect interaction• Binding of pathogens• Interaction with immune receptors• Interaction with intestinal receptors regulating

enzyme secretion

Indirect interactionIndirect interaction• Changing intestinal environment – altering microbial

balance• Antigen presentation to immune system – immune

modulation• Improved protection – optimising mucin layer

Mode of action of nutritional Mode of action of nutritional supplements supplements

Glycans Glycans • A number of carbohydrates (based

on glucose, mannose, galactose, fucose) have been shown to have anti-infective properties

• Mannose and its polymers are the most commonly used products as feed additives and have been shown to reduce Salmonella colonization in chickens.

Mannan-oligosaccharidesMannan-oligosaccharides• Salmonella contain mannose-specific lectins

(Type 1 fimbriae) on the bacterial surface that binds to glycoproteins (rich in mannose) on the intestinal surface.

• Mannose sugars can thereby compete with the intestinal glycoproteins for attachment sites and prevent colonization.

• Salmonella binding has been demonstrated with mannan- oligosaccharide (Bio-Mos) at significantly lower concentrations than that required for purified mannose. (Spring 2000)

• Improve gut health – Optimal performance depends on

good intestinal health• Salmonella exclusion also depends on

excellent gut health – Use Bio-Mos as part of a control plan

to optimise gut health and reduce Salmonella

Bio-Mos & Actigen-Nutritional Tools to Bio-Mos & Actigen-Nutritional Tools to include in include in SalmonellaSalmonella Control Plans Control Plans

Where do we start?Where do we start?• Education and information• Slaughter house hygienic measures• Breeders• Salmonella-free feed• Biosecurity

– Internal and External

• Holistic approach• Improve gut health and immunity

– More research needed

Salmonella control-does it Salmonella control-does it pay off?pay off?

• Consumers, retail, restaurants and catering will use food safety criteria as quality criteria to promote their products.

• Once food quantity has been secured, food quality will be driving the market

Salmonella control on farm Salmonella control on farm and at slaughterand at slaughter

• All biosecurity measures and hygienic measures to decrease Salmonella contamination will promote productivity and health

• Measures to optimize pig gut health has direct return on investment

• In processing, Salmonella control measures will improve food safety

QuestionsQuestions

Organic acidsOrganic acids• Formic, acetic, propionic & butyric acids • Inclusion rate based on feed buffering

capacity (0.5-3%)• Coated butyric acid decreased Salmonella

levels in pig caecal content, whereas uncoated acids did not. (Boyen 2008)

• Good for animal health and performance, variable results for Salmonella reduction

Feed textureFeed texture• Less Salmonella in herds using home

mixed wet feed than in those buying pelleted feed (Denmark, Greece)

• Evidence that coarse ground meal can decrease Salmonella (Mikkelsen 2004)

• Feed is kept longer in stomach-- increases acidity of feed

• Growth performance?

Competitive Exclusion (CE)Competitive Exclusion (CE)

• a kind of probiotic culture that is only given at a single time to the animals.

• It was initially used in poultry production, where newly hatched chicks can be protected from subsequent Salmonella infections by accelerating the establishment of a complex, protective microflora. (Nurmi, 1992)

• CE cultures to neonatal piglets have been shown to reduce Salmonella choleraesuis fecal shedding in pigs and contact pigs during preweaning and weaning period. (Genovese, 2007)

Medium chain fatty acids Medium chain fatty acids (MCFA)(MCFA)

• caproic, caprylic, capric acids. • MCFA decrease Salmonella in vivo in birds

(Van Immerseel, 2004)

• It was proposed that they reduce the invasive capacity of Salmonella by decreasing the expression of genes specifically involved in invasion.

• In vitro laboratory study simulating the porcine cecum indicated that Salmonella could be inhibited by MCFA (Messens 2009)

PrebioticsPrebiotics• Oligosaccharides (soluble fiber), but can also be

proteins, peptides and some types of lipids. • Defined as non-digestible feed ingredients that

beneficially affects the host by selectively stimulating the growth and/or activity of bacteria in the colon and thus improves host health. (Gibson 2005)

• These prebiotics feed probiotics or commensal enteric bacteria and could give them a competitive advantage over potential pathogens such as Salmonella.

• Fructo-oligosaccharides and inulin rat studies indicates that there may be increased colonization with Salmonella using these products. (Ten Bruggencate, 2004)

Essential OilsEssential Oils• A range of essential oils have been

shown to have bacteriostatic or bacteriocidal properties against Salmonella in vitro.

• There is lacking studies about the applicability in pig feed as a Salmonella intervention.

ProbioticsProbiotics• Currently 17 products approved in EU for

pigs (Regulation (EC) No 1831/2003)

• Bacillus, Lactobacillus, Lactococcus, Bifidobacteria, Pediococcus Enterococcus, Saccharomyces

• Stability during heat treatment is a challenge.

• Lactic acid producing probiotics have been shown to decrease Salmonella infection in pigs. (Casey 2007)

A systematic review – feed and A systematic review – feed and feeding management to reduce feeding management to reduce Salmonella Salmonella in slaughter swinein slaughter swine

• O’Connor, AM. Prev Vet Med. 2008 Nov 17;87(3-4):213-28.

• Screened 248 studies, evaluated 15• a low level of comfort among qualified scientists

that the claimed association between non-pelleted feed and reduced Salmonella prevalence is scientifically valid.

• There is no strong evidence regarding associations between Salmonella and feed withdrawal prior to slaughter, feed acidification, heat treatment of feed, pelletized feed versus mash, and wet versus dry feeds.

Summary of responses to Bio-Summary of responses to Bio-MosMos®® addition to sow diets addition to sow dietsSummary of responses to Bio-Summary of responses to Bio-MosMos®® addition to sow diets addition to sow diets

• Sow colostrum production (+ 11%)

• Piglet weight gain first 24 h (+ 39%)

• Colostrum consumption piglet (+ 12%)

• Colostral immune quality (IgA, + 25%)

• Immune status of piglets (IgA, + 17%)

• Preweaning mortality (- 35%)• Litter weight at weaning (+ 8.5%)