Unicomb, Dr. Leanne E.

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©INTERNATIONAL CENTRE FOR DIARRHOEALDISEASE RESEARCH, BANGLADESHJ HEALTH POPUL NUTR 2009 Oct;27(5):599-601ISSN 1606-0997 | $ 5.00+0.20EDITORIALFood Safety: Pathogen Transmission Routes,  Hygiene Practices and PreventionCorrespondence and reprint requests should be addressed to:Dr. Leanne E. UnicombHead, Water and Sanitation ClusterProgramme on Infectious Diseases and Vaccine SciencesHealth Systems and Infectious Diseases DivisionICDDR,BGPO Box 128, Dhaka 1000BangladeshEmail: leanne@icddrb.orgFax: +880-2-8811568Improvements in food safety require initiatives that address risks identified along the ‘farm-to-fork continuum’. Two papers in this issue of the Journal look at opposite ends of this continuum; an article by Akoachere et al. examines a common foodborne pathogen (Salmonella Typhimurium) in livestock (1) and Takanashi et al. assess the impact of food hygiene in the home on diarrhoea (2). Foodborne disease is defined as illness resulting from consumption of contaminated food; food can be contaminated with microbial pathogens or a toxic substance (3). Many common foodborne pathogens are zoonotic (4). To attribute diarrhoeal disease to zoonotic transmission or other transmis-sion routes, data collected for specific pathogens through investigations of outbreaks, analytical studies, and laboratory-based studies can provide insights. Transmission from animals to humans can occur through direct contact (5), consumption or handling of meat (6), consumption of unpasteuri-zed milk (7), untreated water (8,9) or consumption of contaminated fresh produce (10). In the article by Akoachere et al., microbial sub-typing was used as a means to link Salmonella Ty-phimurium-related disease in humans with ani-mal reservoirs (1). In investigations of outbreaks, the linkage between humans and animals is clear as there is laboratory evidence, along with informa-tion for a specific exposure window (11,12). In ana-lytical studies, epidemiological evidence suggests a link by detecting an elevated risk of being an S. Typhimurium case among those exposed to meats (13) or animal contact (14). These data, however, lack accompanying microbiological evidence. In the article by Akoachere et al. (1), microbiological evidence is proposed, in the absence of an epidemio-logical link. There are limitations to this approach to attributing food-animal exposure to human dis-ease and so the findings should be interpreted with caution. The authors conclude that their findings are circumstantial. Using microbial subtyping data to attribute human disease to a source can be use-ful for prioritizing intervention strategies. Recent advances in the use of Salmonella subtyping data to attribute human infections to animal reservoirs have been described (15). This may be further as-sisted by the wider use of multiple-locus variable-number tandem repeat analysis (MLVA) developed for several Salmonella serovars (16-18). The method has the advantages of being rapid, cheap, and re-producible, offering advantages over traditional Salmonella serotyping and phage typing. MLVA has initially been used in outbreak situations and is now being applied as a routine method in some settings (19).The study described by Akoachere et al. also reports antimicrobial resistance of the S. Typhimurium iso-lates (1). There has been considerable debate on an-timicrobial resistance among foodborne pathogens and the role of clinical usage versus antimicrobial use during food-animal rearing. The source of resis-tance remains controversial and has been the subject of many analytical studies that include human and/or animal isolates and data on antimicrobial agent consumption for humans and animals (20-23). In addition to identifying areas for improvement at the food production and food processing level, collecting evidence of food safety at the point of consumption is warranted. Epidemiological data suggest that poor food-hygiene practices are res-ponsible for a substantial proportion of foodborne disease (24). In this issue, an article by Takanashi et al. examines the role of food-hygiene practices on diarrhoeal disease among children (2). They found limited association between food-hygiene or general hy-giene behaviours and diarrhoea. This is consistent with the findings from a systematic review of the effect of domestic kitchen-hygiene practices on di-arrhoeal disease in developed countries (25). There is, however, evidence of a role of poor hygiene Unicomb LEFood safetyJHPN600practices in diarrhoeal disease from investigation of outbreaks and environmental studies (26,27). Col-lecting accurate information on hygiene practices is challenging. Self-reported food-handling and hy-giene practices at home are unreliable compared to observed behaviours (24); this was acknowledged by the authors. For example, they found no as-sociation between diarrhoea and handwashing practices, a finding at odds with studies that have demonstrated the effectiveness of handwashing in-terventions on diarrhoea (28). The study reported in this issue focused on practices important for foodborne transmission, which include handwash-ing; this can have an impact on person-to-person transmission. Among the age-group of study chil-dren, diarrhoea may be due to pathogens acquired by the person-to-person and fomite transmission routes, in addition to the foodborne transmission route.From a disease-prevention perspective, hygiene ef-forts at both farm and fork-end of the continuum are worth pursuing. Strong evidence of the impact of these initiatives will be required to satisfy the food industry and policy-makers that changes are needed. In addition to addressing animal and hu-man hygiene, continued research to attribute dis-ease to pathways and vehicles to target those of the greatest impact and/or with viable practical solu-tions is required. REFERENCES1. Akoachere J-FTK, Tanih NF, Ndip LM, Ndip RN. Phe-notypic characterization of Salmonella Typhiumuri-um isolates from food-animals and abattoir drains in Buea, Cameroon. J Health Popul Nutr 2009;27:612-18.2. Takanashi K, Chonan Y, Quyen DT, Khan NC, Pou-del KC, Jimba M. Survey of food-hygiene practices at home and childhood diarrhoea in Hanoi, Viet Nam. J Health Popul Nutr 2009;27:602-11.3. Foodborne disease. In: Wikipedia. (http://www.wiki-pedia.org, accessed on 29 August 2009).4. Tauxe RV. Emerging foodborne pathogens. Int J Food Microbiol 2002;78:31-41.5. Stirling J, Griffith M, Dooley JS, Goldsmith CE, Loughrey A, Lowery CJ et al. Zoonoses associated with petting farms and open zoos. Vector Borne Zoo-notic Dis 2008;8:85-92.6. McPherson M, Lalor K, Combs B, Raupach J, Stafford R, Kirk MD. Serogroup-specific risk factors for Shiga toxin-producing Escherichia coli infection in Austra-lia. Clin Infect Dis 2009;49:249-56.7. Oliver SP, Jayarao BM, Almeida RA. Foodborne patho-gens in milk and the dairy farm environment: food safety and public health implications. Foodborne Pat-hog Dis 2005;2:115-29.8. Ashbolt RA, Kirk MD. Salmonella Mississippi infec-tions in Tasmania: the role of native Australian ani-mals and untreated drinking water. Epidemiol Infect 2006;134:1257-65.9. Sutherland SJ, Gray JT, Menzies PI, Hook SE, Mill-man ST. Transmission of foodborne zoonotic patho-gens to riparian areas by grazing sheep. Can J Vet Res 2009;73:125-31. 10. Lynch MF, Tauxe RV, Hedberg CW. The growing bur-den of foodborne outbreaks due to contaminated fresh produce: risks and opportunities. Epidemiol In-fect 2009;137:307-15.11. Smith KE, Medus C, Meyer SD, Boxrud DJ, Leano F, Hedberg CW et al. Outbreaks of salmonellosis in Min-nesota (1998 through 2006) associated with frozen, microwaveable, breaded, stuffed chicken products. J Food Prot 2008;71:2153-60.12. Kivi M, Hofhuis A, Notermans DW, Wannet WJ, Heck ME, Van De Giessen AW et al. A beef-associated outbreak of Salmonella Typhimurium DT104 in the Netherlands with implications for national and inter-national policy. Epidemiol Infect 2007;135:890-9.13. Delarocque-Astagneau E, Bouillant C, Vaillant V, Bou-vet P, Grimont PA, Desenclos JC. Risk factors for the occurrence of sporadic Salmonella enterica serotype ty-phimurium infections in children in France: a national case-control study. Clin Infect Dis 2000;31:488-92. 14. Doré K, Buxton J, Henry B, Pollari F, Middleton D, Fyfe M et al.; Multi-Provincial Salmonella Typhimuri-um Case-Control Study Steering Committee. Risk factors for Salmonella Typhimurium DT104 and non-DT104 infection: a Canadian multi-provincial case-control study. Epidemiol Infect 2004;132:485-93.15. Hald T, Vose D, Wegener HC, Koupeev T. A Bayes-ian approach to quantify the contribution of ani-mal-food sources to human salmonellosis. Risk Anal 2004;24:255-69.16. Davis MA, Baker KN, Call DR, Warnick LD, Soyer Y, Wiedmann M et al. Multilocus variable-number tan-dem-repeat method for typing Salmonella enterica serovar Newport. J Clin Microbiol 2009;47:1934-8. 17. Torpdahl M, Sørensen G, Lindstedt BA, Nielsen EM. Tandem repeat analysis for surveillance of human Salmonella Typhimurium infections. Emerg Infect Dis 2007;13:388-95.18. Ross IL, Heuzenroeder MW. A comparison of two PCR-based typing methods with pulsed-field gel elec-trophoresis in Salmonella enterica serovar Enteritidis. Int J Med Microbiol 2009;299:410-20.Unicomb LEFood safetyVolume 27 | Number 5 | October 2009 60119. Gilbert GL. Using MLVA to type strains of Salmonella Typhimurium in New South Wales. N S W Public Health Bull 2008;19:29-31.20. Aarestrup FM, Wegener HC, Collignon P. Resistance in bacteria of the food chain: epidemiology and control strategies. Expert Rev Anti Infect Ther 2008;6:733-50.21. Wassenaar TM, Silley P. Antimicrobial resistance in zoonotic bacteria: lessons learned from host-specific pathogens. Anim Health Res Rev 2008;9:177-86.22. Nelson JM, Chiller TM, Powers JH, Angulo FJ. Fluo-roquinolone-resistant Campylobacter species and the withdrawal of fluoroquinolones from use in poultry: a public health success story. Clin Infect Dis 2007;44:977-80.23. Cox LA, Jr. Enrofloxacin in poultry and human health. Emerg Infect Dis 2006;12:872-3.24. Redmond EC, Griffith CJ. Consumer food handling in the home: a review of food safety studies. J Food Prot 2003;66:130-61.25. Stenberg A, Macdonald C, Hunter PR. How effective is good domestic kitchen hygiene at reducing diar-rhoeal disease in developed countries? A systematic review and reanalysis of the UK IID study. BMC Public Health 2008;8:71.26. Olsen SJ, Hansen GR, Bartlett L, Fitzgerald C, Sonder A, Manjrekar R et al. An outbreak of Campylobacter je-juni infection associated with food handler contami-nation; the use of pulsed-field gel electrophoresis. J Infect Dis 2001;183:164-7.27. Butz AM, Fosarelli P, Dick J, Cusack T, Yolken R. Prev-alence of rotavirus on high-risk fomites in day-care facilities. Pediatrics 1993;92:202-5.28. Curtis V, Cairncross S. Effect of washing hands with soap on diarrhea risk in the community: a systematic review. Lancet Infect Dis 2003;3:275-81.Leanne E. UnicombHead, Water and Sanitation ClusterProgramme on Infectious Diseases and Vaccine  SciencesHealth Systems and Infectious Diseases DivisionICDDR,BGPO Box 128, Dhaka 1000Bangladesh

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