Chapter 2 Entamoeba coli 2.1 Overview of Entamoeba coli Amoebiasis is defined as infection with the protozoan parasite Entamoeba histolytica . However there are several Entamebas species which are closely related to E . histolytica such as E. dipar and E. coli . (Anonymous 1997)
Entamoeba coli are a non-pathogenic species of Entamoeba that frequently exists as a commensal parasite in large intestine of the human. Both cysts and trophozoites of the species are passed in stool and considered diagnostic (CDC 2009). Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. Colonization of the nonpathogenic amebae occurs after ingestion of mature cysts in fecally-contaminated food, water, or fomites(CDC 2009).
2.2 Summary of data:
Rendtorff, R. C. (1954). "The Experimental Transmission of Human Intestinal Prozoan Parasites.I. Endamoeba coli Cyst Given in Capasules." American Journal of Hygien 59 : 196-208- studied the Entamoeba coli exposure to human volunteers (Rendtorff 1954). Known numbers of cysts of E. coli were administered orally in capsules to volunteers to determine numbers of parasites necessary to establish the infection
Table 2.1. Summary of data for Entamoeba coli Host Route/ Optimized Experiment Dose Best Fit Reference Type/Pathogen # of Response Parameter ID Number Units Model 50 Strain Doses (s) α = 0.10 Rendtorff Ingestion No. of 1 Humans Infection Exponential N50 = 340.78 1954 – 5 cysts 340.78
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2.3 Optimized Models and Fitting Analyses 2.3.1 Optimization Output for experiment 1 Table 2.2. Dose response model data Table 2.3. Goodness of Fit and Model Selection Non- χχχ2 Dose Infected Total 0.95,1 χχχ2 infected 0.95,m-k Model Deviance ∆∆∆ DF p- p-value 10000 2 0 2 value 1000 0 2 2 Exponent 9.49 27.82 4 100 2 2 4 ial 3.84 1.36E-05 22.78 10 3 7 10 Beta 0 7.81 5.04 3 1 1 7 8 Poisson 0.169 Rendtorff (1954) Beta Poisson is best fitting model
Table 2.4 Optimized parameters for the best fitting (beta Poisson), obtained from 10,000 bootstrap iterations MLE Percentiles Parameter Estimate 0.5% 2.5% 5% 95% 97.5% 99.5% α 0.10 ------
N50 340.78 ------LD 50 340.78 5.91 17.33 29.94 147504.7 2081588 1.19E+10 (spores)
Figure 2.1 Parameter scatter plot for beta Poisson Figure 2.2 beta Poisson model plot, with model ellipses signify the 0.9, 0.95 and 0.99 confidence bounds around optimized model confidence of the parameters.
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References
Anonymous (1997). "Entamoeba taxonomy." Bulletin of the World Health Organization 75 (3): 291-292.
CDC (2009). Intestinal Amebae. D. o. P. Diseases.
Rendtorff, R. C. (1954). "The Experimental Transmission of Human Intestinal Prozoan Parasites. I. Endamoeba coli Cyst Given in Capasules." American Journal of Hygien 59 : 196-208.
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