If brain function is severely affected, physical therapy and speech therapy may be needed after the infection is controlled.
The outcome varies. Some cases are mild and short, and the person fully recovers. Other cases are severe, and permanent problems or death is possible.
The acute phase normally lasts for 1 to 2 weeks. Fever and symptoms gradually or suddenly disappear. Some people may take several months to fully recover.
Permanent brain damage may occur in severe cases of encephalitis. It can affect:
When to Contact a Medical Professional
Go to the emergency room or call the local emergency number (such as 911) if you have:
Other symptoms of encephalitis
Children and adults should avoid contact with anyone who has encephalitis.
Controlling mosquitoes (a mosquito bite can transmit some viruses) may reduce the chance of some infections that can lead to encephalitis.
Apply an insect repellant containing the chemical, DEET when you go outside (but do not use DEET products on infants younger than 2 months).
Remove any sources of standing water (such as old tires, cans, gutters, and wading pools).
Wear long-sleeved shirts and pants when outside, especially at dusk.
Children and adults should get routine vaccinations for viruses that can cause encephalitis. People should receive specific vaccines if they are traveling to places such as parts of Asia, where Japanese encephalitis is found.
Vaccinate animals to prevent encephalitis caused by the rabies virus.
Beckham JD, Tyler KL. Encephalitis. In: Bennett JE, Dolin R, Mandell GL, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2014:chap 91.
Simon DW, Da Silva YS, Zuccoli G, Clark RSB. Acute encephalitis. Crit Care Clin. 2013;29:259-277.
Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.