Re: Viruses
"Medical doctors believe that once you get a virus its always with you, mostly in a dormant state"
Just wanted to make a quick correction on that + give you some references to read up on viruses if you're interested.
No scientists believes that all viruses that infect you are with you forever. Many viruses cause an acute infection and then are gone (for example, cold and flu viruses) - your body fights them off + you're rid of them. Other viruses often stick around forever, causing chronic infections. A generalization (that there are lots of exceptions to!) is that RNA viruses tend to cause acute infections, DNA viruses tend to cause chronic infections. Chronic viral infections are not necessarily dormant (an example of this would be HIV). The word scientists usually use for dormant is "latent", and it unfortunately has two different meanings. I believe you were referring to cellular latency (a virus hiding out, not actively replicating), rather than clinical latency (a clinically asymptomatic period of infection). These don't necessarily overlap. VZV (chickenpox/shingles) and HSV (herpes simplex) are interesting cases in many ways (there's a lot going on when it comes to herpesviruses!). There's no one thing that allows all chronic viruses to stick around. They have different strategies and combinations of strategies that make them very successful as persistent infections (latency can be one of them. the herpesviruses you mentioned are successfully latent because they hide in the ganglia, which is a VERY good place to hide for several reasons. For example, it's not subject to much immune surveillance there). But often when you get sick with a virus, fight it off, and get better, the virus is gone. Finito. There is no latent virus hiding in your body somewhere. Even when the virus is gone, however, you will have an adaptive immune response to it (this is the principle upon which vaccines work. The adaptive immune system has memory, so if you have memory B-cells to a particular virus, you're making antibodies to it at a low levels and the next time you meet that virus, you will make tons of antibodies that will be faster, more effective, etc. Antibodies are only one type of immune response, but they're the type most people are familiar with). In that sense, your body remembers the viruses you have met "forever" (sometimes. Depends on the virus and the person. Doesn't ALWAYS last forever), but in many cases, the virus will have been long gone. In any case, you should not have any traces of the flu virus you had when you were 10 years old still in your body, OK?
http://gsbs.utmb.edu/microbook/ch046.htm
http://www.ohsu.edu/microbiology/courses/mbim608/Wong-Latency_5_26.pdf