"QuizID"	"AppID"	"AppTitle"	"TaskID"	"TaskText"	"RecordID"	"Record"	"Type"	"Note"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	1	"Set the model parameters to the following values. 1000 initially susceptible individuals, 1 initially infected host, no pathogen in the environment, simulation duration 1 year. We'll first look at direct transmission. Set transmission rate of _b~I~ = 0.004_, environmental transmission _b~P~ = 0_. Set environmental pathogen shedding and clearance rates to 0. Assume that the duration of the infectious period is 15 days long (and a month has 30 days). Turn off births and deaths for now. Run the simulation. You should get the usual direct transmission dynamics and a single outbreak. You should be left with around 203 susceptibles at the end of the simulation. Remember that in a model like this, where the only flow from the susceptible class is outflow through becoming infected, everyone who is not in the susceptible compartment at the end has been infected. Thus the total number of infected during the outbreak is the different between susceptibles at the beginning and at the end. Use one of the equations you have learned about in the reproductive number apps to compute _R~0~_."	"T1R1"	"Basic reproductive number"	"Rounded_Integer"	"Report the rounded integer"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	2	"Now try various values for the rate of shedding into the environment, _q_, and environmental clearance _c_. Leave everything else unchanged. As those parameters move away from 0, what do you expect to see? Run the simulation and compare your expectations with the results. Anything surprising happening? Do you understand why you see what you see?"	"T2R1"	"Susceptible left at end of simulation"	"Rounded_Integer"	"Report the rounded integer"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	3	"Now set _q = 100_ and _c = 100_ . Turn off (set to 0) direct transmission. Run to make sure you don't get an outbreak. Now turn on environmental transmission, set it to _b~P~ = 0.004_, the same value you had for direct transmission above. Leave everything else unchanged. Run the simulation. Compare results with those from task 1. You might or might not find the result surprising. Take a close look at the curves for _I_ and _P_."	"T3R1"	"Susceptible left at end of simulation"	"Rounded_Integer"	"Report the rounded integer"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	4	"In the previous task, removal of pathogens in the environment happened at a rate that was so fast that it essentially tracked whatever was going on in the infected population. In such a case, one can make with is called a quasi-steady state approximation for the fast variable and assume that it's change only depends on the change of the variable it tracks. There is some formal way of doing it, a quick and often (but not always) correct way is to set the right side of the equation of the fast variable to 0. Here, that is the environmental variable, so the equation becomes _0=qI-cP_ and from that _P=qI/c_. Since we had _q_=_c_ in the previous task, I and P tracked each other (approximately). That is generally not the case. Explore a more general scenario by setting _q = 100_ and _c = 50_. Have direct transmission off and environmental transmission as in the previous task. Since decay is now slower, pathogen in the environment builds up to higher levels and produces an overall larger outbreak. Look at the maximum values for _P_ and _I_. Compute the ratio and compare that with the equation. Keep exploring how things change for different values of _q_ and _c_."	"T4R1"	"The ratio of the maximum values for P and I, i.e. maximum P/maximum I"	"Rounded_Integer"	"Report the rounded integer"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	5	"It is possible to compute the reproductive number for enviromental transmission. Recall that it is defined as the average number of infectious hosts (of 1 type) that are infected by one infectious host of the same type. Here, we need to go through the environment. First, we need to compute _how many units of environmental pathogen_ an individual host produces before they recover, and then how many hosts are infected per unit of environmental pathogen. This can be done as follows: One infected host sheds pathogen for a duration of _1/g_ at a rate _q_, so the total environmental pathogen produced by that host is _q/g_. This amount of pathogen is around for an average time of _1/c_, during which time it infects new hosts at rate _b~P~_ for a total production of new infected hosts _b~P~_/_c_. To get the number of new infectious hosts produced by one infectious host, one needs to multiply these two quantities. Then, to get the basic reproductive number, one also needs to multiply by the inital number of susceptible to get _R~0~=qb~P~S/(gc))_. Use the values from the last task (_q=100_, _c=50_) to compute _R~0~_ for this simulation. Then use the final-size equation to compute the fraction of susceptible you expect to get for this _R~0~_ value and confirm with the simulation."	"T5R1"	"Value of R0"	"Rounded_Integer"	"Report the rounded integer"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	5	"It is possible to compute the reproductive number for enviromental transmission. Recall that it is defined as the average number of infectious hosts (of 1 type) that are infected by one infectious host of the same type. Here, we need to go through the environment. First, we need to compute _how many units of environmental pathogen_ an individual host produces before they recover, and then how many hosts are infected per unit of environmental pathogen. This can be done as follows: One infected host sheds pathogen for a duration of _1/g_ at a rate _q_, so the total environmental pathogen produced by that host is _q/g_. This amount of pathogen is around for an average time of _1/c_, during which time it infects new hosts at rate _b~P~_ for a total production of new infected hosts _b~P~_/_c_. To get the number of new infectious hosts produced by one infectious host, one needs to multiply these two quantities. Then, to get the basic reproductive number, one also needs to multiply by the inital number of susceptible to get _R~0~=qb~P~S/(gc))_. Use the values from the last task (_q=100_, _c=50_) to compute _R~0~_ for this simulation. Then use the final-size equation to compute the fraction of susceptible you expect to get for this _R~0~_ value and confirm with the simulation."	"T5R2"	"Susceptible left at end of simulation for q=100, c=50"	"Rounded_Integer"	"Report the rounded integer"
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	6	"Use the settings from the previous task and alternate between starting with some non-zero number of infected individuals and no pathogen in the environment, or no infected individuals and some pathogen in the environment. Convince yourself that you always get an outbreak, and if it's not clear why, look at the flow diagram for the model to understand which processes lead to more or less the same outbreak if you start with either non-zero infected individuals or non-zero levels of environmental contamination. Then also turn on direct transmission, such that you now have transmission through both pathways (environmental and direct) and explore how different values affect the outbreak."	"T6R1"	"Nothing"	"None"	""
"DSAIDE_environmentaltransmission"	"environmentaltransmission"	"Environmental Transmission"	7	"Keep exploring by trying different parameters and transmission settings and see how they influence results. You can also turn on births/deaths and see what you get. As you continue your exploration, think about potential real infectious diseases that might be approximated by either one of the transmission types. You could try to find parameter values in the literature that could approximate that disease and run simulations mimicking a specific disease and setting."	"T7R1"	"Nothing"	"None"	""
