General Overview
Salmonella enterica, serovar Typhi (S. Typhi for short, but formerly known as Salmonella typhi or Salmonella typhosa) causes typhoid fever.^{[1]} Paratyphoid fever is a similar syndrome (but less common and less severe than typhoid fever) caused by Salmonella enterica, serovar Typhi (S. Paratyphi).^{[2]} Typhoid and paratyphoid fevers are also jointly known as enteric fever.^{[1]} Other Salmonella enterica serovars (e.g., Enteritidis, Typhimurium) cause a gastroenteritis known as salmonellosis. ^{[2]}
S. Typhi and S. Paratyphi only infect humans and are transmitted by the fecaloral route (Miliotis and Bier 2003). Disease may include any combination of the following: cough, constipation, diarrhea, abdominal pain, anorexia, rose spots on the torso, or fever (Miliotis and Bier 2003). S. Typhi may also be shed asymptomatically for years in the feces of chronic carriers (Miliotis and Bier 2003).
http://www.cdc.gov/nczved/divisions/dfbmd/diseases/typhoid_fever/
Summary of data
There have been two feeding studies^{[3]}^{[4]} in male prisoners of the Quailes strain of S. Typhi (which was named Salmonella typhosa at that time).
Other model fits to these data have been published (Haas, Rose, and Gerba 1999). However, these model fits exclude some of the experimental data for unclear reasons.
Recommended Model
The pooled model of experiment number 79 and 80 is the recommended model. Pooling is statistically accepted and it gives improvement in fits.
ID  # of Doses  Agent Strain  Dose Units  Host type  Μodel  Optimized parameters  Response type  Reference 

79  3  Quailes  CFU  human  betaPoisson 
a = 1.11E01 LD_{50}/ID_{50} = 3.45E+06" N_{50} = 3.45E+06 
disease  Typhoid fever: pathogenesis and immunologic control." The New England journal of medicine. 283 (1970): 13.  "
79, 80  8  Quailes  CFU  human  betaPoisson 
a = 1.75E01 LD_{50}/ID_{50} = 1.11E+06 N_{50} = 1.11E+06 
disease  Study of induced typhoid fever in man. I. Evaluation of vaccine effectiveness." Transactions of the Association of American Physicians. 79 (1966): 361367.  "
80  5  Quailes  CFU  human  betaPoisson 
a = 2.03E01 LD_{50}/ID_{50} = 8.53E+05 N_{50} = 8.53E+05 
disease  Pathogenesis of Shigella dysenteriae 1 (Shiga) Dysentery." Journal of Infectious Diseases. 127 (1973): 3.  "
LD_{50}/ID_{50} = 3.45E+06"
N_{50} = 3.45E+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
LD_{50}/ID_{50} = 1.11E+06
N_{50} = 1.11E+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
LD_{50}/ID_{50} = 8.53E+05
N_{50} = 8.53E+05



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