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 disease can lead to severe complications, including pneumonia, encephalitis (swelling of the brain), and death, especially in children under five years old.
—
Daniel R. Depetris, Newsweek, 25 Mar. 2025
Complications from measles can range from ear infections and diarrhea to pneumonia and encephalitis, or brain swelling.
—Sarah Linn, Sacramento Bee, 20 Mar. 2025
Measles is most often associated with a high fever and rash, but more severe cases can cause pneumonia or encephalitis.
—Hannah Wiley, Los Angeles Times, 19 Mar. 2025
Health experts have stressed the importance of vaccines to stop the spread of measles, an extremely contagious viral infection that can lead to serious, life-threatening health complications like pneumonia or encephalitis – particularly among children younger than 5.
—Marc Ramirez, USA TODAY, 13 Mar. 2025
See All Example Sentences for encephalitis
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Daniel R. Depetris, Newsweek, 25 Mar. 2025
Complications from measles can range from ear infections and diarrhea to pneumonia and encephalitis, or brain swelling.
—Sarah Linn, Sacramento Bee, 20 Mar. 2025
Measles is most often associated with a high fever and rash, but more severe cases can cause pneumonia or encephalitis.
—Hannah Wiley, Los Angeles Times, 19 Mar. 2025
Health experts have stressed the importance of vaccines to stop the spread of measles, an extremely contagious viral infection that can lead to serious, life-threatening health complications like pneumonia or encephalitis – particularly among children younger than 5.
—Marc Ramirez, USA TODAY, 13 Mar. 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 2 Apr. 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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