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Experiment ID
242
Pathogen
Legionella pneumophila
Agent Strain
strain 74/81
Contains Preferred Model
No
Reference
Breiman, R. F., & Horwitz, M. A. (1987). Guinea pigs sublethally infected with aerosolized Legionella pneumophila develop humoral and cell-mediated immune responses and are protected against lethal aerosol challenge. A model for studying host defense against lung infections caused by intracellul. The Journal of Experimental Medicine, 165, 3.
Exposure Route
inhalation
Response
death
Host type
mice
# of Doses
4.00
Dose Units
CFU
Μodel
exponential
k
6.48E-05
LD50/ID50
1.07E+04
Description
mice/ Strain 74/81 data
Dose Dead Survived Total
200 0 10 10
4000 1 9 10
5E+04 12 0 12
4E+05 16 0 16

 

Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom		 χ20.95,1 
p-value 		χ20.95,m-k 
p-value
Exponential 2.34 -0.00145 3 3.84 
1 		7.81 
0.506
Beta Poisson 2.34 2 5.99 
0.311
Exponential is preferred to beta-Poisson; cannot reject good fit for exponential.

 

Optimized k parameter for the exponential model, from 10000 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
k 6.48E-05 5.45E-05 5.45E-05 5.45E-05 9.71E-05 9.71E-05 1.24E-04
ID50/LD50/ETC* 1.07E+04 5.57E+03 7.14E+03 7.14E+03 1.27E+04 1.27E+04 1.27E+04
*Not a parameter of the exponential model; however, it facilitates comparison with other models.

 

Parameter histogram for exponential model (uncertainty of the parameter)

Exponential model plot, with confidence bounds around optimized model

References

  • Fitzgeorge, R. B., Baskerville, A. ., Broster, M. ., Hambleton, P. ., & Dennis, P. J. (1983). Aerosol infection of animals with strains of Legionella pneumophila of different virulence: comparison with intraperitoneal and intranasal routes of infection. Epidemiology & Infection, 90.