Can you tell me how is this disease pathogen move from 'host to host' also how do the hosts respond to the disease in terms of the immune response?

Which pathogen?: Since you didn't specify I will answer broadly and hope this helps. Pathogens can transmit to hosts directly through the air like the flu , through blood / mucous membranes like HIV or through a vector like mosquitos. or even objects like door knobs with the common cold just to name a few. The immune response is complex and varies like branches of the military. More details if requested.