In Reply to: Had it and been back 15 more times posted by splinter on Wednesday, 31. March 2010 at 15:56 Bali Time:
however to develop an immunity to the others after having one you must contract it.
To explain more clearly, I have contracted Dengue Subtype 1 that means that I am now immune to Dengue Subtype 1 only, but I am not at all immune to contracting Dengue Subtype 2,Dengue Subtype 3 or Dengue Subtype 4.
So there is still a risk of infection by Dengue once you have initially contracted the virus.
And with each further time that another Dengue Subtype has been contracted, a more violent antibody reaction occurs - making the body's reaction and overall infection much worse.
I think I've explained it in the easiest to understand manner, but if you want a more technical version, please let me know. I hope this helps your understanding of the virus, I can refer you to other sites that might have information to help you.
(and as I posted above I have also been infected with Dengue and returned to Bali)