Before my trip, I inquired of the local health dept what I should take and they never mentioned malaria. Later, they told me they thought i was going to some resort on the coast and not wandering in the jungle looking for caves.
Ye gads man! Caves?!? That is where the bats and the bat guano are. Willingly going into caves (unless you are a miner) is a bit crazy, but hell, have at it. Willingly going into a certifiable "bat ****" zone without mask, meds and a lot of counseling trying to talk you out of that is nuts.
I went to Costa Rica, visited a volcano. Did not jump into the lava even though the local health department never mentioned I was not fireproof.