Encephalitis is inflammation (swelling) of the brain. Arboviral encephalitis is caused by infectious agents that are spread by insects or other arthropods, like mosquitoes or ticks. Nonarboviral encephalitis is spread in various ways, including person to person, by contaminated food or surfaces, or from certain animals to humans.
Symptoms occur when an organism or agent invades and multiplies in a person’s central nervous system. Infectious agents that can cause encephalitis include bacteria, viruses, fungi, protozoans, and other parasites. Encephalitis can be caused by viruses like herpes viruses, enteroviruses, mumps, measles, and varicella viruses. Other organisms can also cause nonarboviral encephalitis. Some examples are bacteria, such as Listeria and Leptospira, fungi such as Histoplasma capsulatum and Cryptococcus neoformans, protozoa such as Toxoplasma gondii, and metazoan parasites such as Gnathostoma species and Taenia solium.
Postinfectious (or parainfectious) encephalitis is encephalitis or meningoencephalitis that follows or occurs in combination with other viral illnesses that are not central nervous system illnesses. Rarely, encephalitis may occur after a person receives a vaccine. In these cases, symptoms may be due to an allergic reaction rather than from active infection of the central nervous system.
Nonarboviral encephalitis is a syndrome with multiple causes. Most cases are caused by a virus.
The organisms and agents that can cause nonarboviral encephalitis are spread in different ways. The most common viruses are spread through direct or indirect contact with respiratory secretions (saliva, sputum, or nasal mucus) of an infected person.
Symptoms of encephalitis may include fever, headache, seizures, extreme tiredness, or light sensitivity. Additionally, a person with encephalitis may be confused or forgetful and may act strangely. Symptoms vary depending on the agent that is responsible for the illness.
Because encephalitis can be caused by many different organisms or agents, there is no single treatment for infectious nonarboviral encephalitis. It is advised that people maintain good health and hygiene practices to prevent spreading viruses that can cause nonarboviral encephalitis. Some examples of good health and hygiene practices are:
- Staying away from people who are sick.
- Staying home from work, school, and errands when you are sick.
- Covering your mouth and nose with a tissue when coughing or sneezing.
- Washing your hands often.
- Avoiding touching your eyes, nose or mouth.
- Keeping current on all recommended vaccinations.
See CDC’s website, Stopping the Spread of Germs at Home, Work & School, (http://www.cdc.gov/flu/protect/stopgerms.htm) for more information on good health and hygiene practices.
Recent Texas Trends
There were 130 cases of nonarboviral encephalitis reported in Texas from 2002 to 2012. Due to small case counts, there are no data trends to report.