Attention all virus experts/medical personnel! question on a virus!?!

Attention all virus experts/medical personnel! question on a virus!?

my extended family has been passing this fast-moving virus back and forth for 3 weeks now. every time we all get together 2 or 3 of us will get sick the next day w/ horrible vomiting and diarrhea. almost everyone in the family has gotten it, and now some are getting a second dose! my mother-in-law is in very poor health, in a nursing home, and she seems to be a common link, she is always present when we get sick. but she has never gotten sick herself! my question is: can someone carry a virus and not get sick themselves, and also, how long will a virus live on a surface, like a counter top?

It is possible to be infected by certain viruses without having any symptoms or only mild ones. The influenza virus is an example. Most of the symptoms of the flu virus are actually caused by the body's immune response. When someone is very old, or young, or immune-compromised they may have little or no symptoms.
It is unlikely that healthy individuals would suffer a second bout of similar symptoms caused by the same virus in a short period of time. The body builds an effective immune response during the first exposure and quickly rids the body of the virus on subsequent exposures. Its more likely a different virus or bacterial infection.
The amount of time that a virus will survive on surfaces is highly variable. Some viruses can survive almost indefinitely while others die immediately.
I've never been taught this but it makes sense that someone who has a decreased immune response (such as an elderly person) could act as a reservoir of virus for infecting others. But there are probably many other possible sources of infection in a nursing home.