PowerPoint Presentation KLA 304 and 604 Foodborne Pathogens Module 2C EMERGING FOODBORNE PATHOGENS How is an “emerging pathogen” defined? 1 Increase in prevalence (or going to ) 2 New (virulent) strai.
KLA 304 and 604 Foodborne Pathogens Module 2C EMERGING FOODBORNE PATHOGENS Definitions How is an “emerging pathogen” defined? 1.Increase in prevalence (or going to…) 2.New (virulent) strain varieties e.g mutation, genetic rearrangement 3.Infections appear in “new populations” i.e expansion or change in susceptible groups Covid-19 is a classic example for emerging (radically so) Definitions cont’d 4.Old infection spreads by a new transmission route Unknown, unstudied or unsuspected organisms that cause disease or poisoning – microbes to be “watched” that is they could re-emerge i.e measles, syphilis Emergence factors Factors that could influence or induce the emergence or re-emergence of foodborne pathogens Microbial adaptation to stress - increased resistance to food processing/preservation hurdles, antibiotic resistance Climate change – increased populations in reservoirs? Increased range of disease vectors Ecosystem change – as above Centralisation of food manufacture and distribution Human behaviour – increased consumption of RTE foods, abuse of used-by-dates Aging populations – decreased immune responses Emergence factors Factors that could influence or induce the emergence or re-emergence of pathogens Poverty Disruption to public health services/measures e.g war, cost savings Lack of vigilance/surveillance e.g cost savings, complacency 10 Intent to harm …bioterrorism Interaction of factors Contamination or presence in the supply chain/ Pathogen environment Environment Production systems Adaptation Distribution systems Change “Consumer environment” Human host Immune status Quality of life Unknown factors -Unknown etiology e.g 80% of foodborne illnesses -How much sickening is due to still unknown microbes/ viruses? - Are there unforeseen (or invisible) underlying trends? Most diseases that are emerging are viral Bacterial infectious agents include AMRs, Listeria, anthrax, cholera, diphtheria, bubonic plague, E coli O104:H4 Highly contextual Time scale is 20-25 years Increase in prevalence Considered over a 20 to 25-year (generational) timescale Some examples: - Salmonella Enteriditis associated with eggs, replacing Salmonella Typhimurium - Trematode infections, increasing in tropical countries - Brucella, Arcobacter (zoonotic origins) - Non-O157 E coli relacing O157 strains - Hepatitis E virus - Clostridioides difficile Foodborne pathogens that have emerged since the 1980s –– most recent emergences are highlighted in red • • • • Campylobacter jejuni Campylobacter fetus ssp fetus – probably zoonotic Cryptosporidium parvum Cyclospora cayetanensis – Central America • Non O157 Escherichia coli e.g O104:H4 outbreak in Germany • • • • • Listeria monocytogenes Salmonella Enteritidis and other serotypes – increasing in Australia Invasive non-typhoidal Salmonella (Africa mainly) Brucella spp – brucellosis – acquired from raw animal products Arcobacter butzleri – as Brucella also contaminated water • Clostridioides difficile – spore contamination of raw foods? • Nitzschia pungens (cause of amnesic shellfish poisoning, not observed since 1987) • Trematode infections – below the radar – include liver flukes, lung flukes and intestinal flukes Example: arise of non-O157 VTEC E coli serotypes Pathogenic verotoxin (VT) producing E coli -All form verotoxins, Shiga-like toxins and Shiga toxins -Most disease is from sporadic occurrences -Over 400 serotypes known from humans -Virulence varies since several virulence determinants are derived from introductions by phage transduction - supershedding cattle (E.coli >104 CFU/g faeces) the main source? Non-O157 E coli serotypes In 1982 O157 serotype emerged, assoc with undercooked meat, subsequently to fresh produce Increased evidence of non-O157 serotypes emerging 100 90 % of cases 80 70 Proportion of non-O157 E coli infections since 1998 60 50 40 30 20 10 Data from Johnson et al (2006) Clinical Infectious Diseases 43:1587–1595 www.foodsafetycentre.com.au Generalised transmission scenario: Do/how human (pathogenic) strains cycle through the food supply chain? soil/plant material/wild or domesticated animals manure food animals Other raw foods e.g fresh produce raw animal derived foods Food processing factories RTE foods/Retail Restaurants/hone Humans (clinical) Known pathogens spreading to new places or using new vehicles - Globalization provides an potential avenue for the spread of pathogens - Food-borne bacterial pathogens are essentially ubiquitous - Survival on or in food itself, especially relatively unprocessed food e.g frozen vegetables, herbs, mixed Ingredient products - Survival in the processing/transport environment e.g on surfaces, packaging materials Known pathogens spreading to new places or using new vehicles Dispersion of food-borne parasites e.g Trichinella Old pathogens appearing as “new” food-borne pathogens Possibility that a normally non-food related pathogen makes an adaptation or humans “provide an opportunity” for a leap to food as a transmission mode e.g hardier strains? Source e.g an animal Processing storage Vast majority inactivated but maybe some survive select resistant /robust strains? Survives in food product e.g RTE Example: - Increasing prevalence of pathogenic genotype - Mainly nosocomial, severe disease especially in the elderly (around 10% mortality when it progresses to pseudomembranous colitis) -Zoonotic: various livestock reservoirs -Has been detected in retailed meat products, raw vegetables 20% of ground meat in Canada +ve for C difficile (Weese, 2009) Clostridioides difficile cont’d - Robust (heat resistant and sanitation resistant due to spores) Resists most common antibiotics - Fastidious Prevention by probiotics? - Can be community acquired i.e children are carriers - Is it an unsuspected cause of food-derived illness or is it just paranoia? “New” food vehicles for food-borne pathogens e.g fresh produce, new convenience foods Salmonella in low moisture food products e.g almonds, peanuts, breakfast cereal, chocolate, crisps, infant formula, peanut butter Yersinia pseudotuberculosis - fresh produce E coli/Salmonella – fresh fruit, salads Clostridium botulinum – vegetable juices Campylobacter – vegetables (peas) Hepatitis A/Norovirus - vegetables, fruits Listeria monocytogenes – just about everything! Food as vehicles or human complacency and/or economic limitations? New or unsuspected foodborne pathogens arising from “nature’s bounty” Arcobacter spp Plesiomonas shigelloides Brucella spp Helicobacter pullorum Cronobacter sakazakii Escherichia albertii (Hafnia alvei) Campylobacter concisus, C fetus Mycobacterium avium subsp paratuberculosis Laribacter hongkongensis New or suspected foodborne pathogens Mycobacterium avium (subsp paratuberculosis) “Map” - Causes Johne’s disease in livestock - Connected to Crohn’s disease in humans? - Might survive pasteurisation (by sheltering in milk lymphocytes) and is ubiquitous in some dairy cattle (screening is done to avoid this) - really slow growing, very fastidious thus hampering studies QUESTIONS: What is an emerging foodborne infectious disease and what factors could contribute to their appearance? How human-run systems contribute or could contribute to the increased prevalence of a foodborne pathogen? How could a virulent (foodborne or waterborne) microbe arise independent of a human managed system? How can emerging pathogens be managed in the food supply chain assuming the pathogen is identified?