THe control group would be healthy volunteers to start. This is what most control groups are in initial studies. And you would not want them to be contacts of the patient either for fear of common environmental exposures.
What other cohort would you use? According to Jason Fukuda includes a high percentage of MDD. You would not want a high percentage of Psychological disorders mixed in with your cohort. That is what has weekened the CDC studies for years.
An outbreak cohort would be real nice and clean. Unless someone subscribes to them being hysteria as the Reeves led CDC program has in the past.
I would like to see an autopsy studay that had inline Village and Lyndonville patients. At least a nice chunk of them in that study so to speak.
