Communicable diseases, also referred to an as infectious or contagious diseases, are caused by bacteria organisms, viruses, fungi and protozoa. Communicable diseases such as the common cold, influenza or gastroenteritis are spread by direct contact with an infected person or by touching an object contaminated with the transmittable organism.
Common Cold
The common cold is a communicable disease caused by more than 200 airborne viruses, although the highly contagious rhinovirus is the most common culprit, notes MayoClinic.com. The common cold is spread by breathing in droplets containing viral particles, direct hand-to-hand contact with an infected person or by touching the surface of an object containing viral particles. Children are more likely than adults to develop a common cold--six to 10 times per year as opposed to two to four times a year in adults.
Influenza
The influenza virus is a highly contagious viral infection of the upper respiratory tracts. The influenza virus is classified as A, B or C depending on its surface proteins and antigens. According to the Merck Manuals, influenza A and influenza B are the most common types of the virus with influenza A causing 95 percent of all flu cases. The incubation period for the influenza virus is one to four days followed by the sudden onset of a fever, chill, body aches, cough and runny nose. In children, the elderly or immunocompromised patients, the influenza virus can cause pneumonia and death.
Gastroenteritis
Gastroenteritis is medical condition characterized by an inflammation of the stomach and intestines. Gastrointestinal infections, also known as the stomach flu, is most commonly caused by viruses such as the norovirus or rotavirus that usually causes large outbreaks in confined spaces. Bacterial organisms can also cause gastroenteritis in salmonella infections. Gastroenteritis is different from other communicable diseases in that is not transmitted via direct contact or airborne viruses. Gastrointestinal infections are transmitted through contaminated food, water source or improper hand washing after a bowel movement.
