Mucous membranes are easier to access for these viruses but are bathed in liquids that provide some protection either through the viscosity of the fluid or the presence of secreted IgA. Enteroviruses resist the acid pH of the stomach and reach the GI tract a major site of replication. Enteroviruses can also replicate in the nasopharyngeal mucosa. One form of enteroviruses, the Rhinoviruses, cause ony the common cold. They replicate in the nasophyngeal mucosa but are destroyed by an acid pH and so cannot replicate in the GI tract. Transmitting virus from one host to the next.
Hands are the most important mechanism for transmitting viruses.
Hands become contaminated with respiratory secretions, oral fluids, and feces. However survival of virus in minute particles of secretion on the hands lasts for a few hours. Fomites such as bedside tables also allow survival of virus. Some viruses are aerosolized and transmitted well this way. Measles and chickenpox virus survive in the air for hours.