Acute encephalitis is swelling or inflammation of a person's brain and nervous system. Infants and elderly people are more at risk for the condition than others, as are people with weakened immune systems. Several viruses as well as bacteria, an allergic reaction, or certain auto-immune disorders can cause acute encephalitis.
Several types of herpes viruses can cause acute encephalitis, including herpes simplex 1 and herpes simplex 2, which usually cause cold sores or genital warts, respectively. Another type of herpes virus, varicella-zoster, which is usually responsible for chickenpox and shingles, can cause encephalitis. Fortunately, a vaccine is available to protect people from the varicella-zoster virus.
Vaccines exist for other viruses that can cause acute encephalitis, including measles, rubella, and rabies. In some cases, a person can have a reaction to a vaccine that causes encephalitis. The viruses transmitted by mosquito bites, such as West Nile, can also lead to encephalitis. Viruses can easily spread from person to person through skin-to-skin contact or sharing food and drink.
The bacteria that causes Lyme disease, commonly spread through tick bites, can also lead to encephalitis. Cases of tuberculosis or syphilis can also cause acute encephalitis if they spread to the brain. Someone who has another condition, such as cancer or AIDS, may end up with encephalitis because his immune system is weak and cannot fight off infections.
In some cases, symptoms resemble those of the flu. In others, the symptoms can be very severe and dangerous. With treatment, most people recover from acute encephalitis within two weeks.
Mild symptoms of acute encephalitis include headache and fever as well as nausea and vomiting. The symptoms usually appear abruptly. A person may seem lethargic and lack energy. She may also be sensitive to light.
More severe symptoms include a change in personality, hallucinations, and memory loss. Some people may lose consciousness or have seizures. Paralysis or loss of muscle control can also occur. It is important that anyone with symptoms of encephalitis see a doctor, and especially important if he exhibits severe symptoms.
Treatment for acute encephalitis depends on how mild or severe the case is. Some patients recover with rest, while others may need antiviral medications or antibiotics. In some cases, medication may not be effective, such as when the condition results from a mosquito bite. After the person recovers, she may also need speech or physical therapy, depending on how much damage the brain suffered.