I think we should get involved because A) We are one of a few countries that has the resources to do so. B) A global pandemic will effect everyone including us.
The longer we delay the harder it will be to stop. It would be nice if other nations pitched in as well and if the countries involved were grateful, but that is not relevant to the fact that it is in our own interest to help solve the problem.
I really do not want to be bleeding out of my eyeballs because every one stood around waiting for the other guy to do it, and the countries involved didn't say please and thank you.
I suggest everyone read The Hot Zone.