What is going on in the body?
- through the bloodstream after a bite from a tick or mosquito
- direct infection of the cells in the brain, often following a head injury
- through the respiratory or gastrointestinal tracts where they then can travel through the bloodstream and invade the brain
- traveling up nerves to the brain. This happens with a dormant herpes infection or after a bite from an animal with rabies.
What are the causes and risks of the condition?
- West Nile virus
- St Louis virus
- Western equine virus
- Eastern equine virus
- La Crosse virus
- Venezuelan equine virus
- Japanese virus
- Colorado tick fever virus
- Powassan virus
- Far Eastern tick-borne virus
- Central European tick-borne virus
- Enteroviruses such as polio virus
- Influenza A virus ( this is the "flu" virus )
- Parainfluenza virus (this is one of the common cold viruses)
- Enteroviruses such as coxsackie and echoviruses
- Varicella zoster virus ( the causes chicken pox and shingles )
- Measles virus
- Rubella virus ( the cause of German measles)
- Epstein Barr virus ( the most common cause of mononucleosis )
- Mumps virus
- Herpes Simplex viruses type 1 (most commonly diagnosed cause of viral encephalitis)
- Rabies virus
- Varicella zoster (rarely)
- Human Immunodeficiency Virus (HIV) which causes AIDS
- Hepatitis C virus
- Herpes Simplex virus type 2 ( the cause of genital herpes)
- Measles virus
- Rubella virus
- Mumps virus
- Varicella Zoster virus
- Mycoplasma ( usually causes "walking" pneumonia )
- Leptospira ( transmitted to humans with contact with urine, blood, or tissue from an infected animal )
- Listeria ( usually affects pregnant women after eating tainted food )
- Mycobacteria ( tuberculosis is caused by a bacteria in this group )
- Treponema pallidum ( the cause of syphilis )
- Rickettsii ( Rocky Mountain Spotted fever and Ehrlichiosis are caused by members of this family transmitted by tick bite )
Important fungal infections causing encephalitis (most commonly these occur in people with poor immune systems ) include:
- Histoplasma ( usually a lung infection following exposure to bat droppings )
- Toxoplasma ( transmitted to humans who ingest raw meat )
- Cysticercosis ( transmitted after ingestion of the eggs of the pork tapeworm )
- Naegleria ( usually occurs after swimming in muddy fresh water reservoirs )
- Plasmodium ( this is the cause of malaria )
- Drugs ( nonsteroidal anti-inflammatory drugs such as ibuprofen, anti-seizure drugs )
- Connective tissue disorders ( i.e. Lupus, Behcet's, Sarcoidosis )
What can be done to prevent the condition?
- Diseases such as polio, measles, mumps, chicken pox, and rubella can be prevented by vaccination; therefore, adults and children should stay up to date on physician recommended vaccinations.
- Practice frequent hand washing when exposed to all animals, raw meat, or eggs.
- When in the outdoors, adorn long sleeve shirts and pants and use a repellant such as DEET to prevent transmission of diseases by mosquitoes and ticks.
- If traveling internationally, make sure to get the appropriate vaccinations and prophylactic medications specific to the area where you will be going.
- Avoid unsafe sexual practices and illicit drug use.
How is the condition diagnosed?
- antibody titer blood tests to detect antibodies to certain organisms
- blood cultures to detect organisms in the blood
- cranial CT scan
- cranial MRI
- electroencephalogram, also called EEG, which shows brain waves
- polymerase chain reaction, a blood test that identifies organisms by their genes
- occasionally a brain biopsy may be warranted to make the diagnosis.
Long Term Effects
What are the long-term effects of the condition?
What are the risks to others?
What are the treatments for the condition?
- acetaminophen or ibuprofen for
- antibiotics for infections caused by bacteria
- anticonvulsants to treat
- antiviral medicines for infections caused by a virus
- corticosteroids to reduce brain swelling
- sedatives for
What are the side effects of the treatments?
What happens after treatment for the condition?
How is the condition monitored?