The longer it is outside the body, the less the chance is for transmission to occur. Normally, the virus will be dead within minutes after it is outside the body. Simply put, The virus can only survive in the specific environmental conditions found inside the human body. Once the virus is outside the body, it is in a very hostile environment, and the virus cannot survive, unless it gets into another persons body within minutes. Symptoms merely suggest to a physician what illnesses might be the cause of a persons problems.
Physicians then depend on doing laboratory tests to determine the exact cause of the problem.
The only thing that symptoms tell you is, if they do not go away, or if they get very severe, then you need to see a doctor. That's all they tell you. It's also important to remember that a person can have HIV and even full-blown AIDS, and have no symptoms at all. Here again, is why we depend so much on laboratory testing. If a person has been at risk of infection, we strongly encourage that person to get tested, regardless of whether they have any symptoms or not.