Is it possible that my body fought off the west Nile virus or dengue?

Well im not sure that i ever had these viruses but when i came back from El Salvador in 2006 from vacation i was feeling very sick with all the symptoms of dengue and west Nile. El Salvador is tropic meaning the disease can live there. Well i was sick for 3 weeks straight then all of a sudden all went away. Is it actually possible for your immune system to fight it off i haven't had any symptoms return in 2 years.