Do they receive extra pay for dealing with such? I'm watching the news about troops being sent to West Africa and thought of this. Do we know which type of units were sent? Mobile hospital units?

It's possible but not likely that they could receive imminent danger pay. I say unlikely because that would undercut the civilan command authority's political position that there is little danger involved for the deployed forces and this is just a run of the mill humanitarian relief mission such as the relief mission to the Philippines last year after hurricane Haiyan. They probably will get family separation allowance for the duration of the deployment but unlike being deployed in support of OEF their pay will not be tax free.

Imminent danger is tied to being in hostilities. You get it if you are within a designated region.

Family separation is paid out if you are away from your family for 30 days or more due to orders. Single service member gets screwed on that.

In short, no, they shouldnt receive anything additional. Though I don't know if other services have things similar to sea and sub pay.