encephalitis
noun
en·ceph·a·li·tis
in-ˌse-fə-ˈlī-təs 
plural encephalitides
in-ˌse-fə-ˈli-tə-ˌdēz
: inflammation of the brain that is caused especially by infection with a virus (such as herpes simplex or West Nile virus) or less commonly by bacterial or fungal infection or autoimmune reaction
Note: Encephalitis may be asymptomatic or present with mild to severe symptoms (such as fever, headache, confusion, seizures, or loss of consciousness) sometimes progressing to coma or death.
Examples of encephalitis in a Sentence
Recent Examples on the Web
The price of infection can be high: One in five unvaccinated people with measles will be hospitalized, 1 in 20 children with measles will develop pneumonia, and 1 in 1,000 children with measles will develop encephalitis or swelling of the brain.
—
Neha Mukherjee, CNN, 12 Mar. 2025
About 1 in 1,000 patients develops encephalitis, or swelling of the brain, and there are 1 or 2 deaths per 1,000, according to the Centers for Disease Control and Prevention.
—Akshay Syal, M.d., NBC News, 12 Mar. 2025
About 1 in 1,000 children with measles can develop encephalitis, or brain inflammation, which can cause deafness, convulsions or intellectual disabilities.
—Fernando Cervantes Jr., USA TODAY, 3 Mar. 2025
As many as 1 in 20 kids with measles will get pneumonia, and 1 out of 1,000 will develop encephalitis, or brain swelling — which can lead to death or cause deafness or intellectual disabilities.
—Maria Godoy, NPR, 21 Feb. 2025
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Neha Mukherjee, CNN, 12 Mar. 2025
About 1 in 1,000 patients develops encephalitis, or swelling of the brain, and there are 1 or 2 deaths per 1,000, according to the Centers for Disease Control and Prevention.
—Akshay Syal, M.d., NBC News, 12 Mar. 2025
About 1 in 1,000 children with measles can develop encephalitis, or brain inflammation, which can cause deafness, convulsions or intellectual disabilities.
—Fernando Cervantes Jr., USA TODAY, 3 Mar. 2025
As many as 1 in 20 kids with measles will get pneumonia, and 1 out of 1,000 will develop encephalitis, or brain swelling — which can lead to death or cause deafness or intellectual disabilities.
—Maria Godoy, NPR, 21 Feb. 2025
See All Example Sentences for encephalitis
Cite this Entry
“Encephalitis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/encephalitis. Accessed 25 Mar. 2025.
Copy CitationKids Definition
encephalitis
noun
en·ceph·a·li·tis
in-ˌsef-ə-ˈlīt-əs
(ˌ)en-
: inflammation of the brain
also
: a disease marked by encephalitis
Medical Definition
encephalitis
noun
en·ceph·a·li·tis
in-ˌsef-ə-ˈlīt-əs
plural encephalitides
-ˈlit-ə-ˌdēz
: inflammation of the brain that is caused especially by infection with a virus (such as herpes simplex, varicella zoster, or West Nile virus) or less commonly by bacterial or fungal infection or autoimmune reaction
Note: Encephalitis may be asymptomatic or present with mild to severe symptoms (such as fever, headache, confusion, seizures, or loss of consciousness) sometimes progressing to coma or death.
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