subcutaneous | QMRA wiki

Lassa virus: Dose Response Experiments

General Overview

Lassa virus is an RNA virus belonging to the family of Arenaviridae. As the causative agent of hemorrhagic fever, Lassa virus infects more than 200,000 people per year, causing more than 3,000 deaths with a mortality rate of about 15% among the hospitalized cases. Hemorrhagic fever is highly fatal disease mostly found in West Africa. The disease has an acute phase lasting 1 to 4 weeks, characterized by fever, skin rash with hemorrhages, sore throat, headache, and diarrhea. The U.S.

Read more about Lassa virus: Dose Response Experiments

ID	Exposure Route	# of Doses	Agent Strain	Dose Units	Host type	Μodel	LD50/ID50	Optimized parameters	Response type	Reference
15	inhalation	4.00	Josiah strain	PFU	guinea pig	beta-Poisson	1.43E+04	a = 7.94E-02 N₅₀ = 1.43E+04	death	Stephenson, E. H., Larson, E. W., & Dominik, J. W. (1984). Effect of environmental factors on aerosol-induced Lassa virus infection. Journal of Medical Virology, 14, 4. Retrieved from https://onlinelibrary.wiley.com/doi/abs/10.1002/jmv.1890140402

Exposure Route:

inhalation

# of Doses:

4.00

Agent Strain:

Josiah strain

Dose Units:

PFU

Host type:

guinea pig

Μodel:

beta-Poisson

LD50/ID50:

1.43E+04

Optimized parameters: a = 7.94E-02 N₅₀ = 1.43E+04

Response type:

death

Reference:

Effect of environmental factors on aerosol-induced Lassa virus infection

**Guinea pig/ Josiah strain model data**
Dose	Dead	Survived	Total
5	1	7	8
48	1	7	8
724	3	5	8
5370	4	4	8

**Goodness of fit and model selection**
Model	Deviance	Δ	Degrees of freedom	χ²_0.95,1 p-value	χ²_0.95,m-k p-value
Exponential	14.4	13.8	3	3.84 0.000203	7.81 0.00237
Beta Poisson	0.633	13.8	2	3.84 0.000203	5.99 0.729
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
Parameter	MLE estimate	0.5%	2.5%	5%	95%	97.5%	99.5%
α	7.94E-02	9.77E-04	9.85E-04	9.87E-04	4.57E-01	1.19E+00	5.76E+02
N₅₀	1.43E+04	2.13E-01	9.22E-01	2.90E+00	1.82E+13	3.06E+17	2.25E+34

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

Description

**Human/Staphylococcus aureus**
Dose	Infected	Non-infected	Total
2430000	4	16	20
6270000	8	12	20
1.27E+07	13	7	20
2.5E+07	14	6	20
3.34E+07	19	1	20
3.91E+07	20	0	20

**Goodness of fit and model selection**
Model	Deviance	Δ	Degrees of freedom	χ²_0.95,1 p-value	χ²_0.95,m-k p-value
Exponential	5.52	5.36e-05	5	3.84 0.994	11.1 0.356
Beta Poisson	5.52	5.36e-05	4	3.84 0.994	9.49 0.238
Exponential is preferred to beta-Poisson; cannot reject good fit for exponential.

**Optimized k parameter for the exponential model, from 10000 bootstrap iterations**
Parameter	MLE estimate	Percentiles
Parameter	MLE estimate	0.5%	2.5%	5%	95%	97.5%	99.5%
k	7.64E-08	5.67E-08	6.19E-08	6.41E-08	1.00E-07	1.02E-07	1.35E-06
ID50/LD50/ETC*	9.08E+06	2.70E+06	6.79E+06	6.93E+06	1.08E+07	1.12E+07	1.22E+07
*Not a parameter of the exponential model; however, it facilitates comparison with other models.

Parameter histogram for exponential model (uncertainty of the parameter)

Exponential model plot, with confidence bounds around optimized model

# of Doses

6.00

Μodel

exponential

LD50/ID50

9.08E+06

Dose Units

CFU/cm2

Response

infection

Exposure Route

subcutaneous

Contains Preferred Model

Read more about Optimization Output for Exp. 278

7.64E-08

Experiment ID

278

Host type

human

Description

**Guinea pig/ Josiah strain model data**
Dose	Dead	Survived	Total
0.02	1	9	10
0.2	4	6	10
2	10	0	10
24	10	0	10
2400	15	0	15
240000	5	0	5

**Goodness of fit and model selection**
Model	Deviance	Δ	Degrees of freedom	χ²_0.95,1 p-value	χ²_0.95,m-k p-value
Exponential	0.42	-0.000621	5	3.84 1	11.1 0.995
Beta Poisson	0.42	-0.000621	4	3.84 1	9.49 0.981
Exponential is preferred to beta-Poisson; cannot reject good fit for exponential.

**Optimized k parameter for the exponential model, from 10000 bootstrap iterations**
Parameter	MLE estimate	Percentiles
Parameter	MLE estimate	0.5%	2.5%	5%	95%	97.5%	99.5%
k	2.95E+00	1.35E+00	1.61E+00	1.65E+00	5.43E+00	5.90E+00	7.52E+00
ID50/LD50/ETC*	2.35E-01	9.21E-02	1.17E-01	1.28E-01	4.21E-01	4.32E-01	5.14E-01
*Not a parameter of the exponential model; however, it facilitates comparison with other models.