I am also a photographer and have sold my images for almost 20 years now. I learned a long time ago not to waste time or energy trying to chase down thieves. Like you said, they mostly operate in countries that don't care.
Also, they may have stolen my image, but they haven't stolen my money. They weren't going to buy it and neither were any of the people that deal with them. You can't lose sales you were never going to get to begin with.
In the time it would waste to purse one theft, I can produce dozens of new works.