Communicable diseases, also known as contagious or infectious diseases, are those illnesses that easily transfer from one person to another. Common methods of transfer include direct contact with the source, such as kissing or touching a contaminated surface and then your mouth, or inhaling the droplets of an infected sneeze or cough. Causes for communicable diseases include bacterial and viral agents.
Encephalitis
Encephalitis, a swelling of the brain, ranges from mild to a life-threatening disease, depending on the cause. Encephalitis has three main causes. One type comes from herpes viruses such as Epstein-Barr, herpes simplex and chickenpox. Common childhood viruses that are contagious and can cause encephalitis are the second type, and it includes measles and mumps. The third group of causes includes diseases spread by insects, such as the West Nile virus, Lyme disease and Rocky Mountain spotted fever. KidsHealth reports that while viruses are the main cause for encephalitis, bacteria may cause some cases.
Chlamydia
Chlamydia is the most commonly reported sexually transmitted disease, or STD, in the United States, and many people are unaware that they are infected. There are no symptoms in half of infected men and in 75 percent of infected women, according to the National Women's Health Information Center. The bacteria chlamydia trachomatis causes chlamydia, and it is highly contagious. Chlamydia transfer occurs from an infected person to a partner during vaginal, oral or anal sexual activity. Babies born to infected moms are at risk to get eye infections or pneumonia because of the chlamydia.
Measles
The number of measles cases, a highly contagious viral infection, shows signs of increasing after decades of near eradication, reports MedlinePlus. Contaminated mucus droplets from the mouth, throat or nose pass the disease on to those exposed to the droplets. Anyone without immunity to the disease from being vaccinated or having a history of a measles infection can expect to become infected. The measles virus, a paramyxovirus, remains contagious for four days prior and four days after the rash breakout of measles.
Enteroviruses
The combination of ribonucleic acid and protein makes a group of small viruses known as enteroviruses, explains the National Center for Immunization and Respiratory Diseases. Included in the group are coxsackieviruses, echoviruses, three polioviruses and more than 60 types of non-polio enteroviruses. Contamination occurs through direct contact with respiratory secretions or stool from an infected person or surface.
