You are here

Home / QMRA Framework / Dose Response / Recommended Best-Fit Parameters

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 Host type Agent Strain Response # of Doses Dose Units Reference Links
Acanthamoeba eyes-cornea beta-Poisson a = 0.245


N50 = 19357 (beta=1215)
mice A. castellanii HN-3 and A culbertsoni A1 death 9 no of trophozoites all experiments
Acanthamoeba intranasal beta-Poisson a = 0.245


N50 = 19357 (beta=1215)
mice A. castellanii HN-3 and A culbertsoni A1 death 9 no of trophozoites all experiments
recommended experiment
Adenovirus exponential
k = 6.07E-01
LD50/ID50 = 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. all experiments
Bacillus anthracis exponential
k = 1.65E-05
LD50/ID50 = 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),  all experiments
Burkholderia mallei 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. all experiments
Campylobacter jejuni intragastric beta-Poisson a = 1.44E-01

LD50/ID50 = 8.9E+02
N50 = 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. all experiments
Coxiella burnetii beta-Poisson a = 3.57E-01

LD50/ID50 = 4.93E+08
N50 = 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. all experiments
Cryptosporidium hominis exponential
k = 5.72E-02
LD50/ID50 = 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. all experiments
Cryptosporidium parvum exponential
k = 5.72E-02
LD50/ID50 = 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. all experiments
Echovirus oral beta-Poisson a = 1.06E+00

LD50/ID50 = 9.22E+02
N50 = 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. all experiments
recommended experiment
Entamoeba coli beta-Poisson a = 1.01E-01

LD50/ID50 = 3.41E+02
N50 = 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. all experiments
Enterovirus oral exponential
k = 3.74E-03
LD50/ID50 = 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. all experiments
recommended experiment
Escherichia coli beta-Poisson a = 1.55E-01

LD50/ID50 = 2.11E+06
N50 = 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. all experiments
Francisella tularensis exponential
k = 4.73E-02
LD50/ID50 = 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. all experiments
Giardia duodenalis exponential
k = 1.99E-02
LD50/ID50 = 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. all experiments
Influenza inhalation 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 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. all experiments
Lassa virus exponential
k = 2.95E+00
LD50/ID50 = 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. all experiments
Legionella pneumophila exponential
k = 5.99E-02
LD50/ID50 = 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, all experiments
Mycobacterium avium Intratracheal inoculation exponential
k = 6.93E-04
LD50/ID50 = 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. all experiments
Mycobacterium avium intravenous exponential
k = 6.93E-04
LD50/ID50 = 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. all experiments