A communicable disease is one that is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect.If you caught that disease from another person or animal, it is called a communicable disease. These illnesses are usually caused by viruses or bacteria and are passed through the air, through contact with contaminated surfaces, or through contact with bodily fluids. Examples include colds, the flu, or HIV.