Human digestive system digestive system is subject to a wide range of disorders many of which can be congenital. Mouth diseases can also be caused by pathogenic bacteria, viruses, fungi and as a side effect of some medications. Mouth diseases include tongue diseases and salivary gland diseases. A common gum disease in the mouth is gingivitis which is caused by bacteria in plaque. The most common viral infection of the mouth is gingivostomatitis caused by herpes simplex. A common fungal infection is candidiasis commonly known as "thrush" which affects the mucous membranes of the mouth. There are a number of esophageal diseases such
Central nervous system viral disease Central nervous system viral disease The Central Nervous System controls most of the functions of the body and mind. It comprises the brain, spinal cord and the nerve fibers that branch off to all parts of the body. The Central Nervous System viral diseases are caused by viruses that attack the CNS. Existing and emerging viral CNS infections are major sources of human morbidity and mortality. Virus infections usually begin in the peripheral tissues, and can invade the mammalian system by spreading into the peripheral nervous system and more rarely the CNS. CNS is protected by effective immune responses and