[Verotoxin-producing Escherichia coli: quantitative model of exposure and risk scenarios in cattle carcasses in Argentina].
OBJECTIVE
Quantify contamination by verotoxin-producing Escherichia coli associated with hemolytic uremic syndrome (VTEC-HUS) in cattle carcasses and generate estimates of exposure in three likely scenarios.


METHODS
A model was constructed of the frequency and magnitude of VTEC-HUS contamination from primary production to the removal of the carcasses from cold storage, based on the published scientific information, epidemiological data, and information from local experts. The probability distributions that best described each step in the process and scenarios were input to the @Risk program with multiple simulations using Monte Carlo analysis. Pearson s correlation test was used for the sensitivity analysis.


RESULTS
The estimated frequency of carcasses with VTEC-HUS was 0.37 (95% CI: 0.26 to 0.58) and the final load of VTEC-HUS was 0.47 log CFU/carcass (95% CI: -2.46 to 3.62). The most closely related variables were the fattening system (r = -0.681) and the theoretical concentration of VTEC-HUS on the cattle's skin (r = 0.702). Vaccinating the animals reduced the frequency of VTEC-HUS in the carcasses by 54.1%, although there were no significant changes in the final VTEC-HUS load. Washing the carcasses reduced the final load by 0.42 log CFU/carcass compared with the baseline model, without any change in the frequency. A 50%-60% increase in the percentage of animals fattened in pens would increase the frequency of carcasses contaminated with VTEC-HUS by 15%-23%.


CONCLUSIONS
Vaccinating the animals was the most effective scenario for reducing introduction of the bacteria in the beef production chain. Intensifying livestock production will increase the public health risk due to greater exposure to VTEC-HUS.
Olvera
Adib
A
Escuela Superior de Ciencias Agropecuarias, Universidad Autónoma de Campeche, Campeche, México.
Signorini
Marcelo
M
Tarabla
Héctor
H
D000003:Abattoirs; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D001118:Argentina / Q000453:epidemiology; D002102:Cadaver; D002417:Cattle / Q000382:microbiology*; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology; D003198:Computer Simulation; D004781:Environmental Exposure; D005506:Food Contamination; D005511:Food Handling; D005516:Food Microbiology; D005519:Food Preservation; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control* / Q000662:veterinary*; D006799:Housing, Animal; D006801:Humans; D008460:Meat / Q000382:microbiology*; D008962:Models, Theoretical; D012034:Refrigeration; D012306:Risk; D054323:Shiga-Toxigenic Escherichia coli / Q000302:isolation & purification* / Q000378:metabolism; D014611:Vaccination