I don’t see this as pessimistic as market-neutral. Today they released nurse Pham - cured after only 13 days in hospital. If you have the flu it will take you longer to recover. She is now immune from further infection from Ebola. She did not transmit the disease to anybody else either. So as more and more healthcare workers get cured they will be able to help people who get Ebola. They don’t even have to put on protective clothing because they are immune. As the infection rate becomes less than the number people who have Ebola, then the sickness will eventually disappear. That is just maths.
As for the isolation period just announce in New York and New Jersey. This is counter productive - people will just fly to another airport. What the governors should have added is that people who are isolated will be accommodated in 5-star luxury hotels and paid $1,000 per day for being there. So anybody who arrives from West Africa who has been doing work trying to help people with Ebola will at least have $21,000 to show for their efforts when they have been in quarantine for 21 days.
This would be an incentive to get more health-care workers to Africa where they are desperately needed. But as it is, now nobody will go there to help if they know that they will be confined for 21 days when they come back. I guess the politicians were just pandering to their constituents.