Sure. As long as you can get personal jurisdiction and subject matter jurisdiction. If the person is in the United States and gets in a car accident, for example, it would be possible to sue them in the jurisdiction where the accident occurred. (if they return to Africa, you'll have a hard time getting them served). Also, if the lawsuit is over real estate or other assets that are located in the United States there will be a way to proceed.
If, on the other hand, you are talking about suing a person from Camaroon IN Camaroon, I cannot comment accurately on that. I would expect that you would probably have a REALLY hard time doing that.
Much would depend on where the act for which you want to sue the Cameroonian occurred. Secondly, a lot would depend on where the defendant now resides and whether you can get valid service of process.
