You are here

Home
Experiment ID
79, 80
Pathogen
Salmonella typhi
Contains Preferred Model
1
Reference
Study of induced typhoid fever in man. I. Evaluation of vaccine effectiveness
Host type
human
# of Doses
8.00
Μodel
beta-Poisson
a
1.75E-01
N50
1.11E+06
LD50/ID50
1.11E+06
Dose Units
CFU
Response
disease
Agent Strain
Quailes
Exposure Route
oral (in milk)
Experiment Dataset
Description: 
Model data for S. Typhi (Quailes) in humans [1] [2]
Dose Disease No disease Total
1000 0 14 14
1E+05 28 76 104
1E+05 32 84 116
1E+07 15 15 30
1E+07 16 16 32
1E+08 8 1 9
1E+09 4 0 4
1E+09 40 2 42

 

Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom		 χ20.95,1 
p-value		 χ20.95,m-k 
p-value
Exponential 419 406 7 3.84 
0		 14.1 
0
Beta Poisson 13.8 6 12.6 
0.0321
Neither the exponential nor beta-Poisson fits well; beta-Poisson is less bad.

 

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 1.75E-01 1.21E-01 1.32E-01 1.39E-01 2.23E-01 2.34E-01 2.58E-01
N50 1.11E+06 5.13E+05 6.10E+05 6.72E+05 2.00E+06 2.28E+06 2.95E+06

 

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

References

  1. Hornick, R. B., Woodward T. E., McCrumb F. R., Snyder M. J., Dawkins A. T., & Bulkeley J. T. (Submitted).  De la Macorra F and Corozza FA (1966) Study of induced typhoid fever in man. I. Evaluation of vaccine effectiveness. Transactions of the Association of American Physicians. 79, 361.
  2. Hornick, R. B., Greisman S.E., Woodward T. E., DuPont H. L., Dawkins A. T., & Snyder M. J. (1970).  Typhoid fever: pathogenesis and immunologic control. The New England journal of medicine. 283, 13.