Difference between revisions of "Listeria monocytogenes (Stillbirths): Dose Response Models"

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==='''General overview of ''Listeria monocytogenes'' '''===
 
==='''General overview of ''Listeria monocytogenes'' '''===
  
''Listeria monocytogenes'' is a gram-positive rod-shaped bacterium. It is the causative agent of listeriosis, a serious infection caused by eating food contaminated with the bacteria. The disease generally affects older adults, pregnant women, newborns, and adults with weakened immune systems. However, rarely, persons without these risk factors can also be affected (CDC 2012; Todar 2012).  
+
''Listeria monocytogenes'' is a food-borne pathogen responsible for the illness listeriosis. This  disease is especially severe for susceptible people, including fetuses and immunocompromised individuals (Smith, Takeuchi et al. 2008).  
 
 
The overt form of the disease has mortality greater than 25 percent. The two main clinical manifestations are sepsis and meningitis. Meningitis is often complicated by encephalitis, a pathology that is unusual for bacterial infections (Todar 2012).  
 
  
  
 +
http://www.cdc.gov/listeria/
  
  
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==='''Summary Data'''===
 
==='''Summary Data'''===
  
Smith et al.(2008) studied dose-response model for ''Listeria monocytogenes''- induced stillbirths in nonhuman primates (Smith, Takeuchi et al. 2008) and Williams et al ( 2007 and 2009) explored fetal mortality in guinea pigs after oral exposure (Williams, Irvin et al. 2007; Williams, Castleman et al. 2009).  
+
Smith et al.(2008) studied dose-response model for ''Listeria monocytogenes'' induced stillbirths in nonhuman primates (Smith, Takeuchi et al. 2008) . Thirty-three pregnant rhesus monkeys (''Macaca mulatta'') were identified at 30 gestation days (gd)  and ''L. monocytogenes'' was administered by nasogastric intubation. Animals were observed  daily for changes in behavior or activity or signs of illness such as diarrhea.  Similarly, Williams et al ( 2007 and 2009) explored fetal mortality in guinea pigs after oral exposure (Williams, Irvin et al. 2007; Williams, Castleman et al. 2009).  Timed-pregnant guinea pigs were inoculated ''L. monocytogenes'' with whipping cream  and the doses ranges from 10<sup>4</sup> CFU to 10<sup>8</sup> CFU. The animals were sacrificed on gestation day.  
  
 
{{DRSummaryTableStart|agent=''Listeria monocytogenes''}}
 
{{DRSummaryTableStart|agent=''Listeria monocytogenes''}}
 +
{{DRSummaryTablePreferredModeltworefs|expID= 289,290 |refer1=Smith|reference1=Smith, M. A., K. Takeuchi, et al. (2008). "Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731|refer2=Williams2007|reference2=Williams, D., E. A. Irvin, et al. (2007)."Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128|host=pooled |agentStrain=  |route= oral  |nDoses= 13 |doseUnits= CFU |response= stillbirths |bestFitModel=beta-Poisson|parameters=&#945;  =  4.22E-02 , N<sub>50</sub> =  1.78E+09 |N50= 1.78E+09 }}
 +
{{DRSummaryTableNonpreferredModel|expID= 289 |refer=Smith|reference=Smith, M. A., K. Takeuchi, et al. (2008). "Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731|host= rhesus monkeys |agentStrain=  |route= oral  |nDoses= 8 |doseUnits= CFU |response= stillbirths |bestFitModel=beta-Poisson|parameters=&#945;  =  4E-02 , N<sub>50</sub> =  8.26E+08 |N50= 8.26E+08 }}
 +
{{DRSummaryTableNonpreferredModel|expID= 290 |refer=Williams2007|reference=Williams, D., E. A. Irvin, et al. (2007)."Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128|host= guinea pig |agentStrain=  |route= oral  |nDoses= 5 |doseUnits= CFU |response= fetal  mortality |bestFitModel=beta-Poisson|parameters=&#945;  =  9.36E-02 , N<sub>50</sub> =  4.67E+07 |N50= 4.67E+07 }}
 +
{{DRSummaryTableEnd}}
  
{{DRSummaryTableNonpreferredModel|expID= 289 |refer=Smith, Takeuchi et al. 2008E|reference=Smith, M. A., K. Takeuchi, et al. (2008). "Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731|host= rhesus monkeys |agentStrain=  |route= oral  |nDoses= 8 |doseUnits= CFU |response= stillbirths |bestFitModel=beta-Poisson|parameters= α  =  4E-02 , N<sub>50</sub> =  8.26E+08 |N50= 8.26E+08 }}
 
{{DRSummaryTableNonpreferredModel|expID= 290 |refer=Williams, Irvin et al. 2007|reference=Williams, D., E. A. Irvin, et al. (2007)."Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128|host= guinea pig |agentStrain=  |route= oral  |nDoses= 5 |doseUnits= CFU |response= fetal  mortality |bestFitModel=beta-Poisson|parameters= α  =  9.36E-02 , N<sub>50</sub> =  4.67E+07 |N50= 4.67E+07 }}
 
{{DRSummaryTablePreferredModel|expID= 289,290 |refer=Smith, Takeuchi et al. 2008 and Williams, Irvin et al. 2007|reference=Smith, M. A., K. Takeuchi, et al. (2008). "Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731 and Williams, D., E. A. Irvin, et al. (2007)."Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128|host=pooled |agentStrain=  |route= oral  |nDoses= 13 |doseUnits= CFU |response= stillbirths |bestFitModel=beta-Poisson|parameters= α  =  4.22E-02 , N<sub>50</sub> =  1.78E+09 |N50= 1.78E+09 }}
 
  
 +
==<sup>*</sup>Recommended Model==
  
{{DRSummaryTableEnd}}
+
It is recommended that pooled model of experiment 289 and 290 pooled should be used as the best dose response model. More data means better fit.
  
  
  
  
 +
[[File:Exponential and betapoisson model.jpg|thumb|none|550px]]
  
a:[[File:Exponential and betapoisson model.jpg|thumb|none|550px]]
+
----
  
----
+
==='''Optimization Output for pooled data (experiment 289 and 290)'''===
  
==='''Optimization Output for experiment 289'''===
+
{{DRExperimentDataTable13norefs|title=Rhesus monkey/''Listeria monocytogenes''|pos=Stillbirths|neg=Not stillbirths|d1=316|p1=0|n1=1|t1=1|d2=1580|p2=2|n2=6|t2=8|d3=1E+04|p3=0|n3=4|t3=4|d4=2E+04|p4=0|n4=3|t4=3|d5=1E+05|p5=2|n5=9|t5=11|d6=126000|p6=1|n6=4|t6=5|d7=1E+06|p7=2|n7=7|t7=9|d8=1580000|p8=2|n8=4|t8=6|d9=1E+07|p9=3|n9=6|t9=9|d10=1.26E+07|p10=2|n10=3|t10=5|d11=1E+08|p11=3|n11=1|t11=4|d12=1.26E+08|p12=2|n12=2|t12=4|d13=3.98E+10|p13=1|n13=0|t13=1}}
  
{{DRExperimentDataTable8|title=Rhesus monkey/''Listeria monocytogenes''|reference=Smith, M. A., K. Takeuchi, et al. (2008)."Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731|pos=Stillbirths|neg=Not stillbirths|d1=316|p1=0|n1=1|t1=1|d2=1580|p2=2|n2=6|t2=8|d3=2E+04|p3=0|n3=3|t3=3|d4=126000|p4=1|n4=4|t4=5|d5=1580000|p5=2|n5=4|t5=6|d6=1.26E+07|p6=2|n6=3|t6=5|d7=1.26E+08|p7=2|n7=2|t7=4|d8=3.98E+10|p8=1|n8=0|t8=1}}
 
  
 +
{{DRFit|title=Goodness of fit and model selection|devE=71.8|devB=7.88|delta=63.9|DFE=12|DFB=11|X2bPbetter=3.84|pbPbetter=1.33e-15|X2GOFe=21|pGOFe=1.49e-10|X2GOFb=19.7|pGOFb=0.724|interpretation=Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.}}
  
  
{{DRFit|title=Goodness of fit and model selection|devE=51.4|devB=3.68|delta=47.7|DFE=7|DFB=6|X2bPbetter=3.84|pbPbetter=4.95e-12|X2GOFe=14.1|pGOFe=7.71e-09|X2GOFb=12.6|pGOFb=0.72|interpretation=Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.}}
+
{{DRConfidenceBetaPoisson|title=Optimized parameters for the beta-Poisson model, from 500 bootstrap iterations|MLEa=4.22E-02|p5a=1.14E-02|p25a=1.54E-02|p50a=1.78E-02|p950a=1.26E-01|p975a=1.51E-01|p995a=2.71E-01|MLEN=1.78E+09|p5N=1.74E+06|p25N=4.42E+06|p50N=7.04E+06|p950N=2.28E+15|p975N=8.63E+16|p995N=8.36E+20}}
  
{{DRConfidenceBetaPoisson|title=Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations|MLEa=4E-02|p5a=9.86E-04|p25a=9.94E-04|p50a=1.02E-02|p950a=1.22E-01|p975a=1.96E-01|p995a=3.05E-01|MLEN=8.26E+08|p5N=1.94E+03|p25N=4.54E+04|p50N=5.30E+05|p950N=8.90E+18|p975N=6.18E+22|p995N=4.86E+65}}
 
  
 +
[[File:BPscatter ID289 290.png|thumb|left|500px|'''Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.''']][[File:BPmodel ID289 290.png|thumb|none|500px|'''beta Poisson model plot, with confidence bounds around optimized model''']]<br>
  
  
  
 +
----
  
[[File:BPscatter ID289.png|thumb|left|500px|'''Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.''']][[File:BPmodel ID289.png|thumb|none|500px|'''beta Poisson model plot, with confidence bounds around optimized model''']]<br>
 
  
 +
==='''Optimization Output for experiment 289'''===
  
----
+
{{DRExperimentDataTable8|title=Rhesus monkey/''Listeria monocytogenes''|refer=Smith|reference=Smith, M. A., K. Takeuchi, et al. (2008). "Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731|host= rhesus monkeys|pos=Stillbirths|neg=Not stillbirths|d1=316|p1=0|n1=1|t1=1|d2=1580|p2=2|n2=6|t2=8|d3=2E+04|p3=0|n3=3|t3=3|d4=126000|p4=1|n4=4|t4=5|d5=1580000|p5=2|n5=4|t5=6|d6=1.26E+07|p6=2|n6=3|t6=5|d7=1.26E+08|p7=2|n7=2|t7=4|d8=3.98E+10|p8=1|n8=0|t8=1}}
  
==='''Optimization Output for experiment 290'''===
 
  
  
{{DRExperimentDataTable5|title=Guinea pig/''Listeria monocytogenes''TITLE|reference=Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128|host= guinea pig |pos=Fetal mortality|neg=Not fetal mortality|d1=1E+04|p1=0|n1=4|t1=4|d2=1E+05|p2=2|n2=9|t2=11|d3=1E+06|p3=2|n3=7|t3=9|d4=1E+07|p4=3|n4=6|t4=9|d5=1E+08|p5=3|n5=1|t5=4}}
+
{{DRFit|title=Goodness of fit and model selection|devE=51.4|devB=3.68|delta=47.7|DFE=7|DFB=6|X2bPbetter=3.84|pbPbetter=4.95e-12|X2GOFe=14.1|pGOFe=7.71e-09|X2GOFb=12.6|pGOFb=0.72|interpretation=Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.}}
  
 +
{{DRConfidenceBetaPoisson|title=Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations|MLEa=4E-02|p5a=9.86E-04|p25a=9.94E-04|p50a=1.02E-02|p950a=1.22E-01|p975a=1.96E-01|p995a=3.05E-01|MLEN=8.26E+08|p5N=1.94E+03|p25N=4.54E+04|p50N=5.30E+05|p950N=8.90E+18|p975N=6.18E+22|p995N=4.86E+65}}
  
{{DRFit|title=Goodness of fit and model selection|devE=19.3|devB=1.72|delta=17.6|DFE=4|DFB=3|X2bPbetter=3.84|pbPbetter=2.71e-05|X2GOFe=9.49|pGOFe=0.000677|X2GOFb=7.81|pGOFb=0.632|interpretation=Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.}}
 
  
  
{{DRConfidenceBetaPoisson|title=Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations|MLEa=9.36E-02|p5a=1.19E-02|p25a=2.03E-02|p50a=2.95E-02|p950a=1.10E+00|p975a=1.02E+02|p995a=8.41E+02|MLEN=4.67E+07|p5N=9.56E+05|p25N=2.12E+06|p50N=3.23E+06|p950N=8.13E+11|p975N=4.28E+14|p995N=2.83E+23}}
 
  
  
 +
[[File:BPscatter ID289.png|thumb|left|500px|'''Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.''']][[File:BPmodel ID289.png|thumb|none|500px|'''beta Poisson model plot, with confidence bounds around optimized model''']]<br>
  
  
[[File:BPscatter ID290.png|thumb|left|500px|'''Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.''']][[File:BPmodel ID290.png|thumb|none|500px|'''beta Poisson model plot, with confidence bounds around optimized model''']]<br>
+
----
  
 +
==='''Optimization Output for experiment 290'''===
  
----
 
  
==='''Optimization Output for pooled data (experiment 289 and 290)'''===
+
{{DRExperimentDataTable5|title=Guinea pig/''Listeria monocytogenes''|refer=Williams2007|reference=Williams, D., E. A. Irvin, et al. (2007)."Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128|host= guinea pig |pos=Fetal mortality|neg=Not fetal mortality|d1=1E+04|p1=0|n1=4|t1=4|d2=1E+05|p2=2|n2=9|t2=11|d3=1E+06|p3=2|n3=7|t3=9|d4=1E+07|p4=3|n4=6|t4=9|d5=1E+08|p5=3|n5=1|t5=4}}
  
{{DRExperimentDataTable13|title=Rhesus monkey/''Listeria monocytogenes''|reference="Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731E|pos=Stillbirths|neg=Not stillbirths|d1=316|p1=0|n1=1|t1=1|d2=1580|p2=2|n2=6|t2=8|d3=1E+04|p3=0|n3=4|t3=4|d4=2E+04|p4=0|n4=3|t4=3|d5=1E+05|p5=2|n5=9|t5=11|d6=126000|p6=1|n6=4|t6=5|d7=1E+06|p7=2|n7=7|t7=9|d8=1580000|p8=2|n8=4|t8=6|d9=1E+07|p9=3|n9=6|t9=9|d10=1.26E+07|p10=2|n10=3|t10=5|d11=1E+08|p11=3|n11=1|t11=4|d12=1.26E+08|p12=2|n12=2|t12=4|d13=3.98E+10|p13=1|n13=0|t13=1}}
 
  
 +
{{DRFit|title=Goodness of fit and model selection|devE=19.3|devB=1.72|delta=17.6|DFE=4|DFB=3|X2bPbetter=3.84|pbPbetter=2.71e-05|X2GOFe=9.49|pGOFe=0.000677|X2GOFb=7.81|pGOFb=0.632|interpretation=Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.}}
  
{{DRFit|title=Goodness of fit and model selection|devE=71.8|devB=7.88|delta=63.9|DFE=12|DFB=11|X2bPbetter=3.84|pbPbetter=1.33e-15|X2GOFe=21|pGOFe=1.49e-10|X2GOFb=19.7|pGOFb=0.724|interpretation=Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.}}
 
  
 +
{{DRConfidenceBetaPoisson|title=Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations|MLEa=9.36E-02|p5a=1.19E-02|p25a=2.03E-02|p50a=2.95E-02|p950a=1.10E+00|p975a=1.02E+02|p995a=8.41E+02|MLEN=4.67E+07|p5N=9.56E+05|p25N=2.12E+06|p50N=3.23E+06|p950N=8.13E+11|p975N=4.28E+14|p995N=2.83E+23}}
  
{{DRConfidenceBetaPoisson|title=Optimized parameters for the beta-Poisson model, from 500 bootstrap iterations|MLEa=4.22E-02|p5a=1.14E-02|p25a=1.54E-02|p50a=1.78E-02|p950a=1.26E-01|p975a=1.51E-01|p995a=2.71E-01|MLEN=1.78E+09|p5N=1.74E+06|p25N=4.42E+06|p50N=7.04E+06|p950N=2.28E+15|p975N=8.63E+16|p995N=8.36E+20}}
 
  
  
[[File:BPscatter ID289 290.png|thumb|left|500px|'''Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.''']][[File:BPmodel ID289 290.png|thumb|none|500px|'''beta Poisson model plot, with confidence bounds around optimized model''']]<br>
 
  
 +
[[File:BPscatter ID290.png|thumb|left|500px|'''Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.''']][[File:BPmodel ID290.png|thumb|none|500px|'''beta Poisson model plot, with confidence bounds around optimized model''']]<br>
  
  
 
----
 
----
  
==='''Summary'''===
 
  
The risk of  fetal mortality in nonhuman primate ( rhesus monkeys) and guinea pigs statistically same and hence the pooled model with larger data points is recommended model.
 
  
 
==='''References'''===
 
==='''References'''===
Line 100: Line 99:
 
<references />
 
<references />
  
CDC (2012) "Listeria (Listeriosis)."
 
 
Smith MA, Takeuchi K, et al. (2008) Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates. Infection and Immunity 76(2): 726-731.
 
 
Todar K (2012) Todar's Online Textbook of Bacteriology.
 
 
   
 
   
 
Williams D, Castleman J, et al. (2009) Risk of Fetal Mortality After Exposure to Listeria monocytogenes Based on Dose-Response Data from Pregnant Guinea Pigs and Primates. Risk Analysis 29(11): 1495-1505.
 
Williams D, Castleman J, et al. (2009) Risk of Fetal Mortality After Exposure to Listeria monocytogenes Based on Dose-Response Data from Pregnant Guinea Pigs and Primates. Risk Analysis 29(11): 1495-1505.
  
Williams D, Irvin EA, et al. (2007) Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs. Journal of Food Protection 70(5): 1122-1128.
+
 
  
 
[[Category:Completed Dose Response Models: Bacteria]][[Category:Dose Response Model]][[Category:Pseudomonas aeruginosa]]
 
[[Category:Completed Dose Response Models: Bacteria]][[Category:Dose Response Model]][[Category:Pseudomonas aeruginosa]]
 
<br>
 
<br>
 
<br>
 
<br>

Latest revision as of 14:41, 15 February 2013

Listeria monocytogenes (Stillbirths in animals)

Author: Sushil Tamrakar


General overview of Listeria monocytogenes

Listeria monocytogenes is a food-borne pathogen responsible for the illness listeriosis. This disease is especially severe for susceptible people, including fetuses and immunocompromised individuals (Smith, Takeuchi et al. 2008).


http://www.cdc.gov/listeria/




Summary Data

Smith et al.(2008) studied dose-response model for Listeria monocytogenes induced stillbirths in nonhuman primates (Smith, Takeuchi et al. 2008) . Thirty-three pregnant rhesus monkeys (Macaca mulatta) were identified at 30 gestation days (gd) and L. monocytogenes was administered by nasogastric intubation. Animals were observed daily for changes in behavior or activity or signs of illness such as diarrhea. Similarly, Williams et al ( 2007 and 2009) explored fetal mortality in guinea pigs after oral exposure (Williams, Irvin et al. 2007; Williams, Castleman et al. 2009). Timed-pregnant guinea pigs were inoculated L. monocytogenes with whipping cream and the doses ranges from 104 CFU to 108 CFU. The animals were sacrificed on gestation day.


Experiment serial number Reference Host type Agent strain Route # of doses Dose units Response Best fit model Optimized parameter(s) LD50/ID50
289,290* [1][2] pooled oral 13 CFU stillbirths beta-Poisson α = 4.22E-02 , N50 = 1.78E+09 1.78E+09
289 [1] rhesus monkeys oral 8 CFU stillbirths beta-Poisson α = 4E-02 , N50 = 8.26E+08 8.26E+08
290 [2] guinea pig oral 5 CFU fetal mortality beta-Poisson α = 9.36E-02 , N50 = 4.67E+07 4.67E+07
*This model is preferred in most circumstances. However, consider all available models to decide which one is most appropriate for your analysis.


*Recommended Model

It is recommended that pooled model of experiment 289 and 290 pooled should be used as the best dose response model. More data means better fit.



Exponential and betapoisson model.jpg

Optimization Output for pooled data (experiment 289 and 290)

Rhesus monkey/Listeria monocytogenes
Dose Stillbirths Not stillbirths Total
316 0 1 1
1580 2 6 8
1E+04 0 4 4
2E+04 0 3 3
1E+05 2 9 11
126000 1 4 5
1E+06 2 7 9
1580000 2 4 6
1E+07 3 6 9
1.26E+07 2 3 5
1E+08 3 1 4
1.26E+08 2 2 4
3.98E+10 1 0 1


Goodness of fit and model selection
Model Deviance Δ Degrees
of freedom
χ20.95,1
p-value
χ20.95,m-k
p-value
Exponential 71.8 63.9 12 3.84
1.33e-15
21
1.49e-10
Beta Poisson 7.88 11 19.7
0.724
Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.


Optimized parameters for the beta-Poisson model, from 500 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
α 4.22E-02 1.14E-02 1.54E-02 1.78E-02 1.26E-01 1.51E-01 2.71E-01
N50 1.78E+09 1.74E+06 4.42E+06 7.04E+06 2.28E+15 8.63E+16 8.36E+20


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




Optimization Output for experiment 289

Rhesus monkey/Listeria monocytogenes [1]
Dose Stillbirths Not stillbirths Total
316 0 1 1
1580 2 6 8
2E+04 0 3 3
126000 1 4 5
1580000 2 4 6
1.26E+07 2 3 5
1.26E+08 2 2 4
3.98E+10 1 0 1


Goodness of fit and model selection
Model Deviance Δ Degrees
of freedom
χ20.95,1
p-value
χ20.95,m-k
p-value
Exponential 51.4 47.7 7 3.84
4.95e-12
14.1
7.71e-09
Beta Poisson 3.68 6 12.6
0.72
Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.
Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
α 4E-02 9.86E-04 9.94E-04 1.02E-02 1.22E-01 1.96E-01 3.05E-01
N50 8.26E+08 1.94E+03 4.54E+04 5.30E+05 8.90E+18 6.18E+22 4.86E+65



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



Optimization Output for experiment 290

Guinea pig/Listeria monocytogenes [2]
Dose Fetal mortality Not fetal mortality Total
1E+04 0 4 4
1E+05 2 9 11
1E+06 2 7 9
1E+07 3 6 9
1E+08 3 1 4


Goodness of fit and model selection
Model Deviance Δ Degrees
of freedom
χ20.95,1
p-value
χ20.95,m-k
p-value
Exponential 19.3 17.6 4 3.84
2.71e-05
9.49
0.000677
Beta Poisson 1.72 3 7.81
0.632
Beta-Poisson fits better than exponential; cannot reject good fit for beta-Poisson.


Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
α 9.36E-02 1.19E-02 2.03E-02 2.95E-02 1.10E+00 1.02E+02 8.41E+02
N50 4.67E+07 9.56E+05 2.12E+06 3.23E+06 8.13E+11 4.28E+14 2.83E+23



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




References

  1. 1.0 1.1 1.2 Smith, M. A., K. Takeuchi, et al. (2008). "Dose-Response Model for Listeria monocytogenes-Induced Stillbirths in Nonhuman Primates." Infection and Immunity 76(2): 726-731
  2. 2.0 2.1 2.2 Williams, D., E. A. Irvin, et al. (2007)."Dose-Response of Listeria monocytogenes after Oral Exposure in Pregnant Guinea Pigs." Journal of Food Protection 70(5): 1122-1128


Williams D, Castleman J, et al. (2009) Risk of Fetal Mortality After Exposure to Listeria monocytogenes Based on Dose-Response Data from Pregnant Guinea Pigs and Primates. Risk Analysis 29(11): 1495-1505.