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 Μodel Optimized parameters Host type Agent Strain Exposure Route Response # of Doses Dose Units Reference
Adenovirus
Experiments
exponential
k = 6.07E-01
LD50/ID50 = 1.14E+00

human type 4 inhalation 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
Experiments
exponential
k = 1.65E-05
LD50/ID50 = 4.2E+04

guinea pig Vollum inhalation death 4 spores June, R.. C., Ferguson W.. W., & Worfel M.. T. (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
Experiments
beta-Poisson a = 3.28E-01

LD50/ID50 = 5.43E+03
N50 = 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.
Coxiella burnetii
Experiments
beta-Poisson a = 3.57E-01

LD50/ID50 = 4.93E+08
N50 = 4.93E+08
C57BL/1OScN mice phase I Ohio intraperitoneal 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
Experiments
exponential
k = 5.72E-02
LD50/ID50 = 1.21E+01

human TAMU isolate oral 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
Experiments
beta-Poisson a = 1.01E-01

LD50/ID50 = 3.41E+02
N50 = 3.41E+02
human From an infected human oral 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.
Echovirus
Experiments
beta-Poisson a = 1.06E+00

LD50/ID50 = 9.22E+02
N50 = 9.22E+02
human strain 12 oral 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.
Enterovirus
Experiments
exponential
k = 3.74E-03
LD50/ID50 = 1.85E+02

pig porcine, PE7-05i oral infection 3 PFU CLIVER, DEAN. O. (1981).  Experimental infection by waterborne enteroviruses. Journal of Food Protection. 44, 861–865.
Escherichia coli
Experiments
beta-Poisson a = 1.55E-01

LD50/ID50 = 2.11E+06
N50 = 2.11E+06
human EIEC 1624 oral (in milk) 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
Experiments
exponential
k = 4.73E-02
LD50/ID50 = 1.46E+01

monkey SCHU S-4 inhalation 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
Experiments
exponential
k = 1.99E-02
LD50/ID50 = 3.48E+01

human From an infected human oral 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
Experiments
beta-Poisson a = 5.81E-01

LD50/ID50 = 9.45E+05
N50 = 9.45E+05
human H1N1,A/California/10/78 attenuated strain,H3N2,A/Washington/897/80 attenuated strain intranasal 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
Experiments
exponential
k = 2.95E+00
LD50/ID50 = 2.35E-01

guinea pig Josiah strain subcutaneous 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
Experiments
exponential
k = 5.99E-02
LD50/ID50 = 1.16E+01

guinea pig Philadelphia 1 inhalation 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
Experiments
exponential
k = 6.93E-04
LD50/ID50 = 1000

deer sub sp. Paratuberculosis Bovine oral 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
Experiments
exponential
k = 3.42E-07
LD50/ID50 = 2.03E+06

mice LEE strain intravenous 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
Experiments
exponential
k = 4.91E-01
LD50/ID50 = 1.41E+00

human type 1,attenuated oral (capsule) 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
Experiments
beta-Poisson a = 1.76E+00

LD50/ID50 = 1.04E+05
N50 = 1.04E+05
hamsters scrapie strain 263k oral 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.
Prion
Experiments
beta-Poisson a = 1.76E+00

LD50/ID50 = 1.04E+05
N50 = 1.04E+05
hamsters scrapie strain 263k oral 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
Experiments
beta-Poisson a = 1.9E-01

LD50/ID50 = 1.85E+04
N50 = 1.85E+04
white rabbit contact lens 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.