Can one sick persone get another sick person sick with worse symptoms?

Answer 1

Sure. Some infectious diseases may be only mildly symptomatic in some people and deadly in others. Chicken pox is an example.

Answer 2

Short answer YES!

Whatever person one is infected with and has passed to person two will be a modified version of the first invading organism. Much depends on the immune system of the second person, their general health and susceptibility of their autoimmune system to combat the invader.
Person one may have had a mild dose of the invader or their immune system had coped previously with a similar organism and so has the antibodies available to reduce the severity.

Person two has no previous exposure and so has no antibodies, allowing the replication of the invader to increase unabated. With some people it can take several days to produce enough antibodies to start coping with the problem. in the meantime, toxins being released by the organism can in some cases make the person quite sick or actually kill them. The latter is in extreme indections like pneumonia, Meningitis, Cholera etc.

Answer 3

Yes, depending if the person is a "Carrier" or "Transmitter." a carrier can carry the sickness and go through all the symptoms everyone else does but for a longer period and a transmitter give everyone a little sickness at a time and symptoms may not be near as bad or long as others.