Most communicable diseases are either bacterial or viral and infect the respiratory tract.
Communicable, or infectious diseases, are generated by microorganisms such as parasites, fungi, bacteria, and viruses, which can be spread, directly or indirectly, from one person to person.
A majority of upper respiratory diseases are due to self-limited viral epidemics. Occasionally, bacterial germs may produce upper respiratory infections. Most often, upper respiratory virus is communicable and can spread from person to person by breathing respiratory droplets from coughing or sneezing.
