We generally recommend a single dose-response model, and we justify the decision in terms of specific criteria. This decision is somewhat subjective, since dose response datasets seldom meet all of these criteria. If all available models are unsatisfactory, we choose a single model to ‘recommend with reservations’. Our recommended model will seldom (if ever) be the best model for all applications. The user should carefully choose the model that is most appropriate for their particular problem. 

Criteria for Model Selection

We prefer dose-response models with the following criteria, in rough order of importance: 

  1. Statistically acceptable fit (fail to reject goodness of fit, p > 0.05)
  2. Human subjects, or animal models that mimic human pathophysiology well
  3. Infection as the response, rather than disease, symptoms, or death
  4. Exposure route similar/identical to the exposure route of natural infection
  5. Pathogen strain is similar to strains causing natural infection
  6. Pooled model using data from 2 or more experiments, provided the data sets are statistically similar (fail to reject that datasets are from the same distribution, p > 0.05)
  7. Low ID50/LD50 (to obtain a conservative risk estimate)
Agent Exposure Route Μodel Optimized parameters LD50/ ID50 Host type Agent Strain Response # of Doses Dose Units Reference
Acanthamoeba
all experiments
eyes-cornea beta-Poisson α = 0.245

N50 = 19357
mice A. castellanii HN-3 and A culbertsoni A1 death 9 no of trophozoites
Acanthamoeba
all experiments
intranasal beta-Poisson α = 0.245

N50 = 19357
mice A. castellanii HN-3 and A culbertsoni A1 death 9 no of trophozoites
Adenovirus
all experiments
inhalation exponential
k = 6.07E-01

1.14E+00 human type 4 infection 4 TCID50 Couch, R. B., Cate T. R., Douglas R. G., Gerone P. J., & Knight V. (1966).  Effect of route of inoculation on experimental respiratory viral disease in volunteers and evidence for airborne transmission. Bacteriological Reviews. 30, 3.
Adenovirus
all experiments
intranasal exponential
k = 6.07E-01

1.14E+00 human type 4 infection 4 TCID50 Couch, R. B., Cate T. R., Douglas R. G., Gerone P. J., & Knight V. (1966).  Effect of route of inoculation on experimental respiratory viral disease in volunteers and evidence for airborne transmission. Bacteriological Reviews. 30, 3.
Bacillus anthracis
all experiments
exponential
k = 1.65E-05

4.2E+04 guinea pig Vollum death 4 spores June, RC., Ferguson WW., & Worfel MT. (1953).  Experiments in feeding adult volunteers with Escherichia coli 55, B5, a coliform organism associated with infant diarrhea. American Journal of Hygiene. 57(2), 
Burkholderia mallei
all experiments
beta-Poisson α = 3.28E-01

N50 = 5.43E+03
5.43E+03 C57BL/6 mice and diabetic rat KHW,316c death 10 CFU Brett, P. J., & Woods D. E. (1996).  Structural and immunological characterization of Burkholderia pseudomallei O-polysaccharide-flagellin protein conjugates.. Infection and immunity. 64, 2824–2828.
Campylobacter jejuni
all experiments
intragastric beta-Poisson α = 1.44E-01

N50 = 8.9E+02
8.9E+02 human strain A3249 infection 6 CFU Black, R. E., Levine M. M., Clements M. L., Hughes T. P., & Blaser M. J. (1988).  Experimental Campylobacter jejuni Infection in Humans. Journal of Infectious Diseases. 157, 3.
Coxiella burnetii
all experiments
beta-Poisson α = 3.57E-01

N50 = 4.93E+08
4.93E+08 C57BL/1OScN mice phase I Ohio death 10 PFU Williams, J.. C., & Cantrell J.. L. (1982).  Biological and immunological properties of Coxiella burnetii vaccines in C57BL/10ScN endotoxin-nonresponder mice. Infection and Immunity. 35, 3.
Cryptosporidium hominis
all experiments
oral exponential
k = 5.72E-02

1.21E+01 human TAMU isolate infection 4 oocysts Messner, M. J., Chappell C. L., & Okhuysen P. C. (2001).  Risk Assessment for Cryptosporidium: A Hierarchical Bayesian Analysis of Human Dose Response Data. Water Research. 35, 16.
Cryptosporidium parvum
all experiments
exponential
k = 5.72E-02

1.21E+01 human TAMU isolate infection 4 oocysts Messner, M. J., Chappell C. L., & Okhuysen P. C. (2001).  Risk Assessment for Cryptosporidium: A Hierarchical Bayesian Analysis of Human Dose Response Data. Water Research. 35, 16.
Echovirus
all experiments
oral beta-Poisson α = 1.06E+00

N50 = 9.22E+02
9.22E+02 human strain 12 infection 4 PFU Schiff, G. M., Stefanović G. M., Young E. C., Sander D. S., Pennekamp J. K., & Ward R. L. (1984).  Studies of echovirus-12 in volunteers: determination of minimal infectious dose and the effect of previous infection on infectious dose. The Journal of infectious diseases. 150, 6.
Entamoeba coli
all experiments
beta-Poisson α = 1.01E-01

N50 = 3.41E+02
3.41E+02 human From an infected human infection 5 Cysts Rendtorff, R. C. (1954).  The experimental transmission of human intestinal protozoan parasites. I. Endamoeba coli cysts given in capsules. American journal of hygiene. 59, 2.
Enterovirus
all experiments
oral exponential
k = 3.74E-03

1.85E+02 pig porcine, PE7-05i infection 3 PFU Cliver, D. O. (1981).  Experimental infection by waterborne enteroviruses. Journal of Food Protection. 44, 861–865.
Escherichia coli
all experiments
beta-Poisson α = 1.55E-01

N50 = 2.11E+06
2.11E+06 human EIEC 1624 positive stool isolation 3 CFU DuPont, H. L., Formal S. B., Hornick R. B., Snyder M. J., Libonati J. P., Sheahan D. G., et al. (1971).  Pathogenesis of Escherichia coli diarrhea. The New England journal of medicine. 285, 1.
Francisella tularensis
all experiments
exponential
k = 4.73E-02

1.46E+01 monkey SCHU S-4 death 4 CFU Quan, S. F., McManus A. G., & von Fintel H. (1956).  Infectivity of Tularemia Applied to Intact Skin and Ingested in Drinking Water. Science. 123, 942-943.
Giardia duodenalis
all experiments
oral exponential
k = 1.99E-02

3.48E+01 human From an infected human infection 8 Cysts Rendtorff, R.. C. (1954).  The experimental transmission of human intestinal protozoan parasites. II. Giardia lamblia cysts given in capsules. American journal of hygiene. 59, 2.
Giardia duodenalis
all experiments
stomach tube exponential
k = 1.99E-02

3.48E+01 human From an infected human infection 8 Cysts Rendtorff, R.. C. (1954).  The experimental transmission of human intestinal protozoan parasites. II. Giardia lamblia cysts given in capsules. American journal of hygiene. 59, 2.
Influenza
all experiments
inhalation beta-Poisson α = 5.81E-01

N50 = 9.45E+05
9.45E+05 human H1N1,A/California/10/78 attenuated strain,H3N2,A/Washington/897/80 attenuated strain infection 9 TCID50 Murphy, B. R., Clements M. L., Madore H. P., Steinberg J., O'Donnell S., Betts R., et al. (1984).  Dose Response of Cold-Adapted, Reassortant Influenza A/California/10/78 Virus (H1N1) in Adult Volunteers. Journal of Infectious Diseases. 149, 5.
Lassa virus
all experiments
inhalation exponential
k = 2.95E+00

2.35E-01 guinea pig Josiah strain death 6 PFU Jahrling, P. B., Smith S., Hesse R. A., & Rhoderick J. B. (1982).  Pathogenesis of Lassa virus infection in guinea pigs. Infection and Immunity. 37, 2.
Lassa virus
all experiments
subcutaneous exponential
k = 2.95E+00

2.35E-01 guinea pig Josiah strain death 6 PFU Jahrling, P. B., Smith S., Hesse R. A., & Rhoderick J. B. (1982).  Pathogenesis of Lassa virus infection in guinea pigs. Infection and Immunity. 37, 2.
Legionella pneumophila
all experiments
exponential
k = 5.99E-02

1.16E+01 guinea pig Philadelphia 1 infection 4 CFU 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,
Mycobacterium avium
all experiments
Intratracheal inoculation exponential
k = 6.93E-04

1000 deer sub sp. Paratuberculosis Bovine infection 3 CFU Nisbet, D. I., Gilmour N. J., & Brotherston J. G. (1962).  Quantitative studies of Mycobacterium johnei in tissues of sheep. III. Intestinal histopathology. Journal of comparative pathology. 72, 80.
Mycobacterium avium
all experiments
intravenous exponential
k = 6.93E-04

1000 deer sub sp. Paratuberculosis Bovine infection 3 CFU Nisbet, D. I., Gilmour N. J., & Brotherston J. G. (1962).  Quantitative studies of Mycobacterium johnei in tissues of sheep. III. Intestinal histopathology. Journal of comparative pathology. 72, 80.
Mycobacterium avium
all experiments
exponential
k = 6.93E-04

1000 deer sub sp. Paratuberculosis Bovine infection 3 CFU Nisbet, D. I., Gilmour N. J., & Brotherston J. G. (1962).  Quantitative studies of Mycobacterium johnei in tissues of sheep. III. Intestinal histopathology. Journal of comparative pathology. 72, 80.
Naegleria fowleri
all experiments
intravenous exponential
k = 3.42E-07

2.03E+06 mice LEE strain death 7 no of trophozoites Adams, A. C., John D. T., & Bradley S. G. (1976).  Modification of resistance of mice to Naegleria fowleri infections.. Infection and immunity. 13, 1387–1391.
Poliovirus
all experiments
exponential
k = 4.91E-01

1.41E+00 human type 1,attenuated alimentary infection 3 PD50 (mouse paralytic doses) Koprowski, H. (1956).  Immunization against Poliomyelitis with Living Attenuated Virus. The American Journal of Tropical Medicine and Hygiene. 5, 3.
Prion
all experiments
beta-Poisson α = 1.76E+00

N50 = 1.04E+05
1.04E+05 hamsters scrapie strain 263k death 5 LD50 i.c. Jacquemot, C., Cuche C., Dormont D., & Lazarini F. (2005).  High Incidence of Scrapie Induced by Repeated Injections of Subinfectious Prion Doses. Journal of Virology. 79(14), 
Pseudomonas aeruginosa
all experiments
injected in eyelids exponential
k = 1.05E-04

6.61E+03 Swiss webster mice (5day old) ATCC 19660 death 12 CFU Hazlett, L. D., Rosen D. D., & Berk R. S. (1978).  Age-Related Susceptibility to Pseudomonas aeruginosa Ocular Infections in Mice. Infection and Immunity. 20, 1.
Pseudomonas aeruginosa
all experiments
injected in eyelids beta-Poisson α = 1.9E-01

N50 = 1.85E+04
1.85E+04 white rabbit corneal ulceration 10 CFU Lawin-Brüssel, C. A., Refojo M. F., Leong F. L., Hanninen L., & Kenyon K. R. (1993).  Effect of Pseudomonas aeruginosa concentration in experimental contact lens-related microbial keratitis. Cornea. 12, 1.
Pseudomonas aeruginosa
all experiments
injected in eyelids exponential
k = 3.22E-7

2150065 death 67 CFU Ojielo, C. I., Cooke K., Mancuso P., Standiford T. J., Olkiewicz K. M., Clouthier S., et al. (2003).  Defective phagocytosis and clearance of Pseudomonas aeruginosa in the lung following bone marrow transplantation. The Journal of Immunology. 171, 4416–4424.
Pseudomonas aeruginosa
all experiments
contact lens beta-Poisson α = 1.9E-01

N50 = 1.85E+04
1.85E+04 white rabbit corneal ulceration 10 CFU Lawin-Brüssel, C. A., Refojo M. F., Leong F. L., Hanninen L., & Kenyon K. R. (1993).  Effect of Pseudomonas aeruginosa concentration in experimental contact lens-related microbial keratitis. Cornea. 12, 1.
Pseudomonas aeruginosa
all experiments
contact lens exponential
k = 3.22E-7

2150065 death 67 CFU Ojielo, C. I., Cooke K., Mancuso P., Standiford T. J., Olkiewicz K. M., Clouthier S., et al. (2003).  Defective phagocytosis and clearance of Pseudomonas aeruginosa in the lung following bone marrow transplantation. The Journal of Immunology. 171, 4416–4424.
Pseudomonas aeruginosa
all experiments
contact lens exponential
k = 1.05E-04

6.61E+03 Swiss webster mice (5day old) ATCC 19660 death 12 CFU Hazlett, L. D., Rosen D. D., & Berk R. S. (1978).  Age-Related Susceptibility to Pseudomonas aeruginosa Ocular Infections in Mice. Infection and Immunity. 20, 1.
Pseudomonas aeruginosa
all experiments
intratracheal exponential
k = 1.05E-04

6.61E+03 Swiss webster mice (5day old) ATCC 19660 death 12 CFU Hazlett, L. D., Rosen D. D., & Berk R. S. (1978).  Age-Related Susceptibility to Pseudomonas aeruginosa Ocular Infections in Mice. Infection and Immunity. 20, 1.
Pseudomonas aeruginosa
all experiments
intratracheal beta-Poisson α = 1.9E-01

N50 = 1.85E+04
1.85E+04 white rabbit corneal ulceration 10 CFU Lawin-Brüssel, C. A., Refojo M. F., Leong F. L., Hanninen L., & Kenyon K. R. (1993).  Effect of Pseudomonas aeruginosa concentration in experimental contact lens-related microbial keratitis. Cornea. 12, 1.
Pseudomonas aeruginosa
all experiments
intratracheal exponential
k = 3.22E-7

2150065 death 67 CFU Ojielo, C. I., Cooke K., Mancuso P., Standiford T. J., Olkiewicz K. M., Clouthier S., et al. (2003).  Defective phagocytosis and clearance of Pseudomonas aeruginosa in the lung following bone marrow transplantation. The Journal of Immunology. 171, 4416–4424.
Rhinovirus
all experiments
beta-Poisson α = 2.21E-01

N50 = 1.81E+00
1.81E+00 human type 39 infection 6 TCID50 Hendley, J. O., Edmondson W. P., & Gwaltney J. M. (1972).  Relation between Naturally Acquired Immunity and Infectivity of Two Rhinoviruses in Volunteers. Journal of Infectious Diseases. 125, 3.
Rickettsia rickettsi
all experiments
beta-Poisson α = 7.77E-01

N50 = 2.13E+01
2.13E+01 pooled R1 and Sheila Smith morbidity 27 CFU Saslaw, S., & Carlisle H. N. (1966).  Aerosol infection of monkeys with Rickettsia rickettsii. Bacteriological Reviews. 30, 3.
Rotavirus
all experiments
beta-Poisson α = 2.53E-02

N50 = 6.17E+00
6.17E+00 human 8 FFU Ward, R. L., Bernstein D. I., Young E. C., Sherwood J. R., Knowlton D. R., & Schiff G. M. (1986).  Human Rotavirus Studies in Volunteers: Determination of Infectious Dose and Serological Response to Infection. Journal of Infectious Diseases. 154, 5.
Salmonella anatum
all experiments
beta-Poisson α = 3.18E-01

N50 = 3.71E+04
3.71E+04 human strain I positive stool culture 16 CFU McCullough, NB., & Elsele CW. (1951).  Experimental human salmonellosis: I. Pathogenicity of strains of Salmonella meleagridis and Salmonella anatum obtained from spray-dried whole egg. Oxford Journal of Infectious Diseases. 88(3), 
Salmonella meleagridis
all experiments
beta-Poisson α = 3.89E-01

N50 = 1.68E+04
1.68E+04 human strain I infection 11 CFU McCullough, NB., & Elsele CW. (1951).  Experimental Human Salmonellosis: I. Pathogenicity of Strains of Salmonella Meleagridis and Salmonella Anatum Obtained from Spray-Dried Whole Egg. Oxford Journal of Infectious Diseases. 88(3), 
Salmonella newport
all experiments
exponential
k = 3.97E-06

1.74E+05 human *Salmonella newport* infection 3 CFU McCullough, NB., & Elsele CW. (1951).  Experimental Human Salmonellosis: I. Pathogenicity of Strains of Salmonella Meleagridis and Salmonella Anatum Obtained from Spray-Dried Whole Egg. Oxford Journal of Infectious Diseases. 88(3), 
Salmonella nontyphoid
all experiments
beta-Poisson α = 2.1E-01

N50 = 4.98E+01
4.98E+01 mice strain 216 and 219 death 10 CFU Meynell, G. G., & Meynell E. W. (1958).  The growth of micro-organisms in vivo with particular reference to the relation between dose and latent period. The Journal of Hygiene. 56(3), 
Salmonella typhi
all experiments
beta-Poisson α = 1.75E-01

N50 = 1.11E+06
1.11E+06 human Quailes disease 8 CFU Hornick, RB., Woodward TE., McCrumb FR., Snyder MJ., Dawkins AT., Bulkeley JT., et al. (1966).  Study of induced typhoid fever in man. I. Evaluation of vaccine effectiveness. Transactions of the Association of American Physicians. 79, 361-367.
SARS
all experiments
inhalation exponential
k = 2.46E-03

2.82E+02 mice hACE-2 and A/J rSARS-CoV death 0 PFU
Shigella flexneri
all experiments
beta-Poisson α = 2.65E-01

N50 = 1.48E+03
1.48E+03 human 2a (strain 2457T) positive stool isolation 4 CFU Dupont, H. L. (1972).  Immunity in shigellosis. I. Response of man to attenuated strains of Shigella. Journal of Infectious Diseases. 125, 5-11.
Staphylococcus aureus
all experiments
exponential
k = 7.64E-08

9.08E+06 human infection 6 CFU/cm2 Lawin-Brüssel, C. A., Refojo M. F., Leong F. L., Hanninen L., & Kenyon K. R. (1993).  Effect of Pseudomonas aeruginosa concentration in experimental contact lens-related microbial keratitis. Cornea. 12, 1.
Vibrio cholerae
all experiments
beta-Poisson α = 2.50E-01

N50 = 2.43E+02
2.43E+02 human Inaba 569B infection 6 CFU Diringer, H., Roehmel J., & Beekes M. (1998).  Effect of repeated oral infection of hamsters with scrapie. Journal of General Virology. 79,
Yersinia pestis
all experiments
exponential
k = 1.63E-03

4.26E+02 mice CO92 death 4 CFU Lathem, W. W., Crosby S. D., Miller V. L., & Goldman W. E. (2005).  Progression of primary pneumonic plague: A mouse model of infection, pathology, and bacterial transcriptional activity. Proceedings of the National Academy of Sciences of the United States of America. 102, 17786-17791.