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UV Process Calculations for Food Applications
Published in Tatiana Koutchma, Ultraviolet Light in Food Technology, 2019
The minimum infectious dose is an expression of the lowest number of organisms required to initiate an infection in any individual under given circumstances. The infectious dose for E. coli O157:H7 is not yet known. However, based on the relatively high attack rates during outbreaks, it appears that the number of bacteria required to cause illness is very low. L. monocytogenes is present in a large number of foods but normally in very low numbers, i.e., less than one colony forming unit per gram of food.
Preparing for Hazardous Material Emergencies
Published in Peter A. Reinhardt, Judith G. Gordon, Infectious and Medical Waste Management, 2018
Peter A. Reinhardt, Judith G. Gordon
In addition to degree of hazard or toxicity, the quantity or concentration of the material is a factor in assessment. Chemical and radiation injuries are dose-dependent. In some cases, there may be low-level threshold concentrations, below which injury does not occur. For infectious agents, an exposure below the infectious dose will not result in disease.
Quality and lifecycle management
Published in Sarfaraz K. Niazi, Biosimilars and Interchangeable Biologics, 2016
Prions come from transmissible spongiform encephalopathies (TSE) include scrapie in sheep and goats, chronic wasting disease in mule deer and elk, Bovine spongiform encephalopathy (BSE) in cattle, Kuru and Creutzfeldt-Jacob disease (CJD) in humans. The disease causing agents (prions) replicate in infected individuals generally without evidence of infection detectable by available diagnostic tests applicable in vivo. The major source of contamination of a recombinant product is the use of animal derived raw materials, which could harbor bovine prions (BSE agent). Currently, there are no assays that are sensitive or specific enough to test raw materials or sources, and the only reliable prevention is to include barriers, such as avoidance of animal or human raw materials (e.g., trypsin, serum, transferin, bovine/human serum albumin, protein supplements, and peptones). However, this is not always possible (e.g., in the propagation of cells for the establishment of cell banks) and inactivation and removal procedures during downstream processing become of interest. Milk is unlikely to present any risk of prion contamination. Filtration has proven efficient in the removal of prion particles, Thus, size exclusion partitioning of abnormal prion particles using normal flow filtration or tangential flow filtration resulted in significant reduction of the infectious agent. The most effective inactivation methods include chloride dioxide, glutaraldehyde, 4 M guanidium thiocyanate, sodium dichloroisocyanurate, sodium metaperiodate, 6 M urea, and autoclaving at 121 qC for 15 min of which several will not be suited if the target protein is present. Biological assays such as in vivo infection of susceptible animals are time consuming (months to years). They will not be of practical use in the test of biopharmaceutical products. The best semiquantitative biochemical assays include Western blot, Capillary immunoelectrophoresis, Conformation-dependent immunoassay, and dissociation-enhanced, time-resolved fluoroimmunoassay. The infectious dose is not known. Accept criteria must be decided upon on a case-by-case basis.
Copper nanoparticles toxicity: Laboratory strains verses environmental bacterial isolates
Published in Journal of Environmental Science and Health, Part A, 2018
Absar Alum, Ali Alboloushi, Morteza Abbaszadegan
Pathogenic strains of E. coli are highly infectious with low infectious dose reported for conditions like hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), which may result in renal failure and death.[2] Differences in the nutritional and growth requirement of pathogenic and non-pathogenic strains of E. coli have been reported.[3-5] In general, the pathogenic strains have enhanced capability to adapt to the changing environments.[6-9] Similarly, laboratory and environmental isolates respond differently to stresses by exhibiting different toxicity elicitation pathways.[10] For example, E. coli O157:H7 has been reported to develop increased resistance after repeated exposure to sub-lethal doses of e-beam.[11-13]
Modelling Airborne Transmission and Ventilation Impacts of a COVID-19 Outbreak in a Restaurant in Guangzhou, China
Published in International Journal of Computational Fluid Dynamics, 2021
The infection model in this study assumes an exponential probability density function for infection as a function of dose. Watanabe et al. (2010) found that an exponential model fit the dose–response relationship for infection of both mice to the SARS coronavirus (SARS-CoV) and humans to the HCoV-229E coronavirus. The probability of infection, P(x,t), can be expressed as follows for an exponential distribution: where r = infectivity rate or probability that a single pathogen will cause an infection (infection probability/deposited pathogen); d = dose (TCID50 or PFU); TCID50 = median tissue culture infectious dose; PFU = plaque forming unit (infectious pathogen).
Changes in extreme events and the potential impacts on human health
Published in Journal of the Air & Waste Management Association, 2018
Jesse E. Bell, Claudia Langford Brown, Kathryn Conlon, Stephanie Herring, Kenneth E. Kunkel, Jay Lawrimore, George Luber, Carl Schreck, Adam Smith, Christopher Uejio
Warmer temperatures may increase the reproduction and infectious dose of foodborne pathogens such as Salmonella and Escherichia coli (Juneja et al. 2007). Warmer air and water temperatures may increase pathogen incidence on produce or in seafood, causing gastrointestinal illnesses (Ziska et al. 2016). It is important to note that while prevalence of some pathogens tends to be higher during warmer temperatures, trends vary based on location and pathogen type, and can be additionally affected by either increased or decreased precipitation.