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Experiment ID
82
Pathogen
Shigella flexneri
Agent Strain
2a (strain 2457T)
Contains Preferred Model
No
Reference
DuPont, H. L., Hornick, R. B., Snyder, M. J., Libonati, J. P., Formal, S. B., & Gangarosa, E. J. (1972). Immunity in Shigellosis. I. Response of Man to Attenuated Strains of Shigella. Journal of Infectious Diseases, 125, 1.
Exposure Route
oral (in milk)
Response
illness
Host type
human
# of Doses
5.00
Dose Units
CFU
Μodel
beta-Poisson
a
1.43E-01
N50
3.54E+04
LD50/ID50
3.54E+04
Experiment Dataset
Description
Model data for Shigella flexneri (2a, strain 2457T) in the human 
Dose Illness Not illness Total
1E+04 1 3 4
1E+05 3 1 4
1E+06 7 1 8
1E+07 13 6 19
1E+08 7 1 8

 

Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom		 χ20.95,1 
p-value 		χ20.95,m-k 
p-value
Exponential 73.6 70.2 4 3.84 
0 		9.49 
3.89e-15
Beta Poisson 3.44 3 7.81 
0.329
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 1.43E-01 1.32E-02 2.12E-02 2.63E-02 2.90E-01 3.32E-01 4.27E-01
N50 3.54E+04 1.29E-11 8.16E-07 3.11E-04 3.34E+05 4.65E+05 9.68E+05
Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.
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
beta Poisson model plot, with confidence bounds around optimized model

References

  • Dupont, H. L. (1969). The response of man to virulent Shigella flexneri 2a. Journal of Infectious Diseases, 119, 296-299.