1 / 55

The Past, Present and Future of Salmonella Control in Poultry:

The Past, Present and Future of Salmonella Control in Poultry:. The Example of Salmonella enteritidis Prepared by Richard K. Gast United States Department of Agriculture Agricultural Research Service Southeast Poultry Research Laboratory Athens, Georgia. Modified and presented by.

pjeremy
Download Presentation

The Past, Present and Future of Salmonella Control in Poultry:

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Past, Present and Future of Salmonella Control in Poultry: The Example of Salmonella enteritidis Prepared by Richard K. Gast United States Department of Agriculture Agricultural Research Service Southeast Poultry Research Laboratory Athens, Georgia

  2. Modified and presented by Prof. Dr. Mohamed Refai Department of Microbiology Faculty of Veterinary Medicine Cairo University, Giza, Egypt At the International Poultry Conference in Cairo

  3. The genus Salmonella(Lignieres, 1900) • Salmonella choleraesuis ( Salmon, 1885) • Salmonella typhi (Schroeter, 1886) • Salmonella enteritidis(Gaertner, 1888) • Salmonella london, panama, cairo etc • Salmonella arizonae (Kauffmann, 1964) • Salmonella bongori(LeMinor, 1985) • Salmonella enterica (LeMinor, 1987) Now we have more than 2300 Salmonellae

  4. Classification of Salmonellainto subgenera/ species Kauffmann 1964 LeMinor 1970 • Subgenus I = speciesenterica • Subgenus II = species salamae • Subgenus IIIa = species arizonae • Subgenus IIIb = species diarizonae • Subgenus IV = species houtenae • Subgenus VI = species indica

  5. Salmonella species • Three species * S. cholerae-suis, S. typhosa, S. kauffmanni * S. cholerae-suis, S. typhi, S. enteritidis • One species * S. enteritidis • Two species * S. enterica , S. bongori

  6. Terminology of Salmonella • the complete nomenclature: * S.enterica, subsp. enterica serovar Enteritidis * or Salmonella enterica ser. Enteritidis Salmonella ser. Enteritidis Salmonella Enteritidis

  7. Antigenic formulae of some serovars of Salmonella enterica Group A 1,2,12:a:1,5 ser.Paratyphi-A Group B 1,4,5,12:b:1,2 ser.Paratyphi-B 1,4,5,12:i:1,2 ser.Typhimurium Group C6,7:c:1,5 ser. Choleraesuis Group D 1,9,12:-:- ser.Pullorum 1,9,12:-:- ser.Gallinarum 1,9,12:g,m:1,7 ser.Enteritidis 1,9,12:g,p:- ser.Dublin

  8. SalmonellaEpidemiological Classification • Group 1. Anthropophilic serovars • Salmonella Typhi • Group 2. Zoophilic serovars • Salmonella Gallinarum poultry • Salmonella Choleraesuis swine • Group 3. Serovars with no particular host • All other serovars, including SE

  9. Incidence of Salmonella Enteritidis infections in laying flocks • Environmental samples from 7.1% of commercial laying houses in the USA were positive for Salmonella Enteritidis USDA, 2000

  10. Salmonella Enteritidis infection in manin the USA • Salmonella Enteritidis constitued 5% in 1976 25% in 1994 of human Salmonella reported to CDC

  11. Sources of SE outbreaks in the USA, 1995-1997 In 110 outbreaks reported by CDC • 59% no confirmed vehicle • 34% contaminated shell eggs • 07% other than eggs

  12. Salmonella Enteritidis contamination of shell eggs The transmission of Salmonella Enteritidis by eggs has become a leading public health issue in the USA

  13. Sites of human SE outbreaks in the USA, 1998-1999 Sites Outbreaks • Commercial food preparers 46 • Private homes 19 • Church/community events 10 • Colleges/schools/camps 7 • Nursing homes 5 • Prisons 2

  14. The problem in the past Before 1970 Cracked or dirty table eggs and processed egg products were often implicated in human salmonella outbreaks attention was directed to: external contamination of eggs

  15. Control of External Contaminationof eggs Measures *Stringent regulation for shell eggs inspection *Pasteurization of liquid egg products Results: Eggs were nearly eliminated as significant source of human disease

  16. The new problem A dramatic increase in incidence of human Salmonella Enteritidis infection is principally caused byconsumption of clean and intact but internally contaminated table eggs Attention was directed to Internal contamination of eggs

  17. Epidemiology of Salmonella Enteritidis in poultry • Colonization of intestinal tract • Shedding in feces Horizontal transmission • Invasion and dissemination • Deposition inside eggs Vertical transmission

  18. Internal contamination of eggs • Principally before oviposition • Fecal contamination and penetration of the shell • Contamination during breaking

  19. Salmonella Enteritidis egg contamination Incidence is relatively low, 0.005% in USA (USDA,2000) Eggs contain small number of SE • 95% of naturally contaminated eggs contain<10Humphrey, UK • 78% of contaminated eggs in experimental infection contain <50Gast, USA

  20. Salmonella Enteritidis infection in chickens and egg contamination Consequences Dangerous increase of SE in eggs not before the 3d week of storage at ambient temperature Humphrey & Whitehead,1993

  21. Site of bacterial contamination of eggs * If it is within the nutrient-rich yolk It would lead to rapid and explosive multiplication * If it is in the albumin Multiplication would be restricted by the several inhibitory factors

  22. Site of bacterial contamination ofeggs in experimentally infected hens (Gast and beard, 1990) *SE was isolated from albumin or entire yolk, including vitelline membrane *SE could not be isolated by sampling only the interior contents of yolk

  23. Site of bacterial contamination of eggs Gast and Holt, 2000 • SE can penetrate through the yolk membrane at warm temperature • Instances were reported in which yolk contamination occurred more often than albumin contamination

  24. Detection of Salmonella Enteritidisin eggs is difficult • Low incidence of contamination needs large number of eggs to be examined, 10-30 eggs • Low level of bacterial cells needs long incubation for one or more days

  25. Human Salmonella Enteritidis outbreaks Human infection requires: * Ambient storage temperature that allow multiplication of SE * Cross-contamination of kitchen surfaces and foods * Improper food handling and preparation practices

  26. Problems of Salmonella control in poultry • Infections can be inapparent • Newly hatched poultry are highly susceptible to Salmonella colonization • Salmonellae have a very wide host range • Salmonella can persist in the environment • Manure and dust are present in large quantities in poultry houses

  27. Salmonella Enteritidis Control Strategies Principal objectives *To reduce incidence of infection in egg-laying flocks *To improve the microbial safety of processing, storage and preparation practices for egg and egg-containing foods

  28. Reducing egg contamination Prevention of infection: • Elimination of sources and reservoirs of SE in poultry flocks and facilities • Control of transmission of SE within and between flocks

  29. A. Elimination of sources and reservoirs of Salmonella enteritidis • Sources of contamination • Replacement chicks themselves • Environment of the poultry house, • Rodents, feeds, etc • Measures . Using uninfected chicks • Hygiene (cleaning, disinfection, etc) • Rodent control

  30. Cleaning and disinfection Cleaning and disinfection eliminated SE from about 50% of environmentally positive houses Henzler et al., 1998, Schlosser et al.,1999

  31. Rodent Control Rodent control was the only practice that correlated well with successful control of SE in poultry houses Henzler et al., 1998, Schlosser et al.,1999

  32. B. Control of Transmission within and between flocks Sources of contamination • Direct contact between birds • Carriage by vectors (biological or physical) • Contamination of materials and surfaces within poultry houses • Air movement of contaminated dust

  33. B. Control of Transmission within and between flocks Measures • Reducing the concentration of the circulating particles by negative ionization has reduced experimental horizontal transmission of SE in chicks Gast et al., 1999

  34. Control of Transmission within and between flocks 2.Reducing the susceptibility of chicks to SE infection by vaccination of pullets or hens can significantly reduce fecal shedding, organ invasion and egg contamination (Gast et al., 1992, Zhang-Barber et al., 1999)

  35. Control of Transmission within and between flocks • Vaccination does not create impenetrable barrier against infection • Immunity is not solid and protection is insignificant Davison et al., 1999

  36. Control of Transmission within and between flocks • Prophylactic administration of probiotic bacterial cultures for competitive exclusion of pathogens from the intestinal tract prevents colonization • This approach is less useful in protecting mature hens against environmentally acquired SE

  37. Controversial susceptibility issue Forced molting of laying hens by feed deprivation can increase frequency, transmission and severity of SE infection (Holt, 1993,1995)

  38. Back to the title of the lecture The Past, Present and Future of Salmonella Control in Poultry

  39. Control of Salmonella Enteritidis in the USA:Past efforts, 90-95 Trace-back Testing Program When eggs are implicated as source of human SE infection *Laying flocks are identified *Environmental samples,if + then *Internal tissues are cultured

  40. Trace-back Testing Program In case of SE positive results: • Selling shell eggs is restricted • Producers have to choose between *pasteurization of eggs or *depopulating affected flocks

  41. Trace-back Testing Program Evaluation: During this program • 304 SE outbreaks were reported • 96 outbreaks were due to eggs • 38 flocks were implicated • 9 million layers were depopulated • I billion eggs were diverted for pasteurization

  42. Trace-back Testing Program Evaluation: During this program • SE in cecal samples from hens at slaughter increased from 27% in 1991 to 45% in 1995 • SE in unpasteurized liquid eggs increased from 13% to 19%

  43. Trace-back Testing Program Conclusion: Evident failure due to : *Eliminating a presumably small number of infected flocks *Potentially continuous reintroduction of SE into flocks from diverse environmental sources

  44. Control of Salmonella Enteritidis in the USA: Present efforts Risk Reduction Program Microbiological Quality Assurance Implemented by federal, state and poultry industry

  45. Risk Reduction Program * Use certified SE-free chicks * Control pests, especially rodents * Thorough cleaning & disinfection * Heightened biosecurity * Washing & refrigeration of eggs

  46. Risk Reduction Program • Intensive testing approach * qualifying serological tests * series of environmental tests • Certification of negative flocks • Diversion of eggs from + flocks to pasteurization

  47. Pennsylvania Egg Quality Assurance Program • Purchase chicks from uninfected breeder flocks • Maintain rodent control and biosecurity programs • Keep eggs under refrigeration • Culture environmental samples from chicks, pullets and layers for SE • If +, culture eggs, if +, divert eggs, clean and disinfect thoroughly between flocks

  48. National Poultry Improvement Plan, monitoring breeding flocks • Chicks must originate from participating flocks • Feed must be free of SE • Hatching eggs must be promptly collected and sanitized or fumigated • Blood samples from 300 birds are tested for antibodies, if + culture for SE • Environmental samples are taken at 2-4 w and every 30 days. If + do blood testing

  49. Risk Reduction Program Results • 38% of 47 flocks + in 1992 • 12% + in 1995 **Egg diversion to pasteurization without compensation renders it unpopular by egg-producers

  50. Risk Reduction Program Alternative program • Single environmental test • Positive result requires: * extra cleaning and disinfection * overall review of control program implementation

More Related