General Overview
'Legionella pneumophila (L. pneumophila) causes both Pontiac Fever and an aggressive form of pneumonia. L. pneumophila is a facultative gram negative aerobic rod, commonly found in drinking water distribution systems, cooling tower basin waters, premise plumbing, surface waters, and other engineered water systems.
Legionellosis includes Legionnaires’ disease and a milder febrile illness called Pontiac Fever. Legionnaires’ disease, an atypical pneumonia caused by bacteria of the genus Legionella, is most commonly caused illness by the species L. pneumophila (Lp). Legionnaires' disease has an incubation period commonly cited as of 2 to 10 days from exposure to the appearance of clinical symptoms, but the upper end of the incubation period may be at least 19 days. Symptoms of Legionnaires include: a high fever, chills, headache, muscular pains, dry cough, difficulty breathing and diarrhea, but not all symptoms occur in all in cases. [1]
Summary Data
Muller et al. (1983) exposed outbred, specific pathogenfree, Hartley strain Guinea pigs to aerosols of Legionella Philadelphia 1 strain in a modified aerosol in fection chamber (TriR Instruments, Rockville Centre, N.Y.).[2]
Fitzgeorge et al. (1983) challenged Female DunkinHartley Guineapigs with aerosols of Legionella pneumophila Strain 74/81.[3]
Breiman and Horwitz (1987) exposed Hartley strain Guinea pigs to aerosols of Legionella Philadelphia 1 strain in an aerosol chamber constructed of lucite measuring 13 X 24 X 18 in.[4]
Recommended Model
It is recommended that experiment 241 should be used as the best dose response model. Infection as the endpoint is more protective and useful for disease transmission modeling over other endpoints such as illness and death.
Summary
By increasing the number of data points, the pooling narrows the range of the confidence region of the parameter estimates and enhances the statistical precision.
References
 Armstrong, T. W. (2005). A quantitative microbial risk assessment model for human inhalation exposure to legionella.
 Muller, D., Edwards M. L., & Smith D. W. (1983). Changes in Iron and Transferrin Levels and Body Temperature in Experimental Airborne Legionellosis. The Journal of Infectious Diseases. 147, 2.
 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,
 Breiman, R. F., & Horwitz M. A. (1987). Guinea pigs sublethally infected with aerosolized Legionella pneumophila develop humoral and cellmediated immune responses and are protected against lethal aerosol challenge. A model for studying host defense against lung infections caused by intracellul. The Journal of Experimental Medicine. 165, 3.
k = 5.99E02
LD_{50}/ID_{50} = 1.16E+01



Parameter histogram for exponential model (uncertainty of the parameter)
Exponential model plot, with confidence bounds around optimized model
References
 Muller, D., Edwards M. L., & Smith D. W. (1983). Changes in Iron and Transferrin Levels and Body Temperature in Experimental Airborne Legionellosis. The Journal of Infectious Diseases. 147, 2.
k = 6.48E05
LD_{50}/ID_{50} = 1.07E+04



Parameter histogram for exponential model (uncertainty of the parameter)
Exponential model plot, with confidence bounds around optimized model
References
k = 4.99E05
LD_{50}/ID_{50} = 1.39E+04



Parameter histogram for exponential model (uncertainty of the parameter)
Exponential model plot, with confidence bounds around optimized model
References
 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,
 Breiman, R. F., & Horwitz M. A. (1987). Guinea pigs sublethally infected with aerosolized Legionella pneumophila develop humoral and cellmediated immune responses and are protected against lethal aerosol challenge. A model for studying host defense against lung infections caused by intracellul. The Journal of Experimental Medicine. 165, 3.
k = 4.17E05
LD_{50}/ID_{50} = 1.66E+04



Parameter histogram for exponential model (uncertainty of the parameter)
Exponential model plot, with confidence bounds around optimized model
References
 Breiman, R. F., & Horwitz M. A. (1987). Guinea pigs sublethally infected with aerosolized Legionella pneumophila develop humoral and cellmediated immune responses and are protected against lethal aerosol challenge. A model for studying host defense against lung infections caused by intracellul. The Journal of Experimental Medicine. 165, 3.