General overview

Entamoeba coliare 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 [1]. 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 [1].

E. coli is an intestinal protozoa, which belongs to the genus of Entamoeba that cause disease [1]. One of the diseases caused by some species is Amoebiasis, which is defined as infection with the protozoan parasite Entamoeba histolytica.

Summary of Data

Rendtorff, R. C. (1954) [2] studied the Entamoeba coli exposure to human volunteers with a known numbers of cysts of E. coli were administered orally in capsules to volunteers to determine numbers of parasites necessary to establish the infection.




ID Exposure Route # of Doses Agent Strain Dose Units Host type Μodel Optimized parameters Response type Reference
45 oral 5 From an infected human Cysts human beta-Poisson a = 1.01E-01

LD50/ID50 = 3.41E+02
N50 = 3.41E+02
infection Rendtorff, R C.. "The experimental transmission of human intestinal protozoan parasites. I. Endamoeba coli cysts given in capsules." American journal of hygiene. 59 (1954): 2.
Experiment ID:
# of Doses:
Agent Strain:
From an infected human
Dose Units:
Host type:
Optimized parameters: a = 1.01E-01

LD50/ID50 = 3.41E+02
N50 = 3.41E+02
Humans model data [1]
Dose Infected Non Infected Total
1 1 7 8
10 3 7 10
100 2 2 4
1000 0 2 2
1E+04 2 0 2


Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom
Exponential 27.8 22.8 4 3.84 
Beta Poisson 5.04 3 7.81 
Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.


Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
α 1.01E-01 1.20E-03 2.60E-02 3.61E-02 2.12E-01 2.57E-01 3.08E-01
N50 3.41E+02 5.02E+00 1.73E+01 2.61E+01 1.48E+05 2.08E+06 1.19E+10



Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.


beta Poisson model plot, with confidence bounds around optimized model.