Termite damage (listed property)

[George P.]

Looked at SFH in the rural area of Maryland and the sunroom appear to have a termite damage (not sure about the rest of the house) - can someone possibly explain the options in terms of treating/preventing from further damage - cost (!), options etc.
I understand that all damaged wood will have to be replaced, so I want to take the cost into account along with the termite treatment cost. I have a feeling I will have to exterminator inspect the property every year to be on the safe side - is that the right thing to do? What is the cost if so?

Thank you in advance!