Encephalitis Causes & Risks

Causes

Viral infection of the central nervous system can be asymptomatic, present with mild symptoms, or cause meningitis and/or encephalitis. Most cases of encephalitis are caused by a viral infection. Encephalitis may be sporadic or epidemic. In the United States, the most common cause of sporadic encephalitis is the herpes simplex virus . Epidemic encephalitis are usually mosquito - or tick-borne, which may be dependant on the geography and season.

The most common viruses that cause encephalitis include:

• Viruses carried by mosquitoes such as West Nile virus
• Chickenpox virus
• Herpes simplex virus
• Polio virus
• Epstein-Barr virus
• Measles virus
• Mumps virus
• Rotavirus
• Influenza virus
• Rabies
• Enterovirus

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition. Risk factors for encephalitis include:

• Living, working, or playing in an area where mosquito-borne viruses are common
• Not being immunized against diseases such as:
  • Measles
  • Mumps
  • Chickenpox
  • Polio
• Having cancer
• Taking immunosuppressive medications after organ transplant
• Having AIDS

Newborns of mothers who have genital herpes simplex are at risk for herpes simplex encephalitis.