Does anyone have any idea how to get a refund from an accommodation fully paid for but now we cannot travel to Costa Rica. I paid on Paypal using my credit card. Paypal doesn't help and neither the VISA. Am I totally going to have to swallow the $3600 USD amount? Is there any leverage at all?

That is what travel insurance is for. If you booked non-refundable, pre paid (and don't have insurance) you could be out of luck. Your only recourse is to contact the resort and make a plea for at least a partial refund -- depends entirely on their refund policy and the cancelation terms you agreed to.

Bummer - that's why we buy travel insurance when we are paying out a lot of nonrefundables in advance. That said, years ago we were in Honduras when we had to race home for a family emergency and hadn't purchased travel insurance. Several of the places we'd reserved wouldn't refund the money but were willing to apply it to a future trip; you could at least ask for that.

Was the rate advertised as non-refundable? Have you contacted them directly to ask? An email and/or phone call to a management person may do it...or possibly a credit for a future visit. Maybe like a cruise, if it's far enough in advance, they may give a partial refund. Ask and ye may receive.

When is this trip booked for?
It may not hurt to ask the agent if you can get a refund if the room rents out. Maybe they'll decide to help you out.

I'd definitely contact your hotels and see what they can do for you. People are often willing to work with you when stuff happens.

I had to have unexpected Cancer treatment after I had paid for a place in PV in 2007. The owners not only gave me a refund but inquired later on my condition so I would suggest you ask.
PS 8 years Cancer free as of now.

YOu get better rates by prepaying, so you can't have options like cancelling and getting your money back, it goes together. You wanted the cheaper rate but now want to cancel.

Don't think there is any option iof you didn't buy insurance, I do when I prepay much. YOu can always ask, of course. Not clear what the reason even is, but I wouldn't expect a business to give you back your money for violating the contract by which you got a cheaper deal.

Agreeing with others above... you are not owed anything, but because of the reason you need to cancel you might find an owner or business that shows compassion/generosity and is willing to refund part or all of what you paid. You can only ask.

Am I wrong, or do I not see any indication that it was a price based on it being non-refundable? And why that was my first question to the OP. Some hotels and sites like Airbnb can require prepayment but some of the prepaid rates are refundable. But without a reply we won't know.

I've had a similar situation - I pre-paid but due to health issues I had to cancel last minute (within a week of when I was supposed to be traveling). The hotels I contacted all refunded my money. I wrote a lengthy email explaining the circumstances in regards to my health and how disappointed I was that I would have to cancel and they were all understanding. People in Costa Rica seem to be very kind and hopefully will be sympathetic to your situation. I would say this is your best bet without travel insurance. To make you feel better, even with travel insurance sometimes they don't refund your money. Good luck and hope things get better for you!