This was a lowish budget film shown on TV back in the day. Probably 80s early 90s at latest. All I can remember is some scenes. A group of castaways or hikers are going through the jungle on an island and they find a long abandoned concrete mouldy building they go inside and find a lab where they were once trying to make fruit that wouldnt go rotten.. there is an orange or some fruit sitting in a glass lab box which looks perfectly fresh but when they touch it it proves to be rotten inside and melts. The ending is they all get off the island I believe however one of the guys gets infected and they have this scene of him lying sweaty and delerious where his forehead and cheeks are pulsating. There is a female narrator saying this guy may have become psychic or still dreams of the island. (terribly open ended) I consider anyone who can discover this film from such little information to be the greatest unsolved film deducer of all time.