Rare Pediatrics News

Disease Profile

Eastern equine encephalitis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset

All ages





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

EEE; Triple E


Nervous System Diseases; Viral infections


Eastern equine encephalitis (Triple E) is an illness caused by a virus that comes from an infected mosquito bite. Most people who are infected have no symptoms, but some may develop fever, headaches, and vomiting. Symptoms occur within 4-10 days of being infected and most recover in 1-2 weeks. A small number will develop swelling of the brain and severe neurological symptoms that can be permanent. Triple E can also lead to coma and death. This condition is caused by a type of arbovirus and is transmitted by a mosquito which has bitten an infected bird or reptile. Diagnosis is based on the symptoms, specific findings in the blood, and occasionally by an MRI of the brain. There is no specific treatment for Triple E. It is managed by taking care of the symptoms. Prevention includes avoiding mosquito bites and controlling mosquito populations.[1][2][3][4]


The following list includes the most common signs and symptoms in people with eastern equine encephalitis (Triple E) virus infections. These features may be different from person to person. Some people may have more symptoms than others and symptoms can range from mild to severe. This list also does not include every symptom or feature that has been described in this condition.[1][4]

  • Fever
  • Chills
  • Fatigue
  • Vomiting
  • Focal neurological signs
  • Cranial nerve palsies (weakness or loss of function of a large nerve)
  • Coma
  • Seizures

Most people who are infected with the Triple E virus do not get sick. Some develop flu-like symptoms (fever, chills, vomiting) within 4-10 days after being infected. If the infection reaches the brain it can lead to seizures, coma and sometimes, death. Some people may have brain damage that leads to paralysis, intellectual disability or changes in behavior or personality.[1][4]


Eastern equine encephalitis (Triple E) is caused by a type of virus called an arbovirus. Humans catch this virus through a bite from certain types of mosquitos.[2]


Eastern equine encephalitis (Triple E) is diagnosed in someone who is sick through tests that look for evidence of the triple E virus in blood, tissue or other body fluids. Sometimes imaging studies, such as an MRI or CT scan can be helpful.[1][5]


There is no specific treatment for eastern equine encephalitis (Triple E) virus. Treatment is based on symptoms. The best way to avoid getting Triple E is to avoid mosquito bites.[1][4] 

Specialists who might be involved in the care of someone with Triple E include:

  • Infectious disease specialist
  • Internal medicine or general practitioner

Learn more

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • You can obtain information on this topic from the Centers for Disease Control and Prevention (CDC). The CDC is recognized as the lead federal agency for developing and applying disease prevention and control, environmental health, and health promotion and education activities designed to improve the health of the people of the United States.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Eastern equine encephalitis. Click on the link to view a sample search on this topic.


  1. Berlin D, Gilani AI, Grewal AK, Fowkes M. Eastern equine encephalitis. Pract Neurol. Oct 2017; 17(5):387-391. https://pubmed.ncbi.nlm.nih.gov/28754695.
  2. Gill CM, Beckham JD, Piquet AL, Tyler KL, Pastula DM. Five emerging neuroinvasive arboviral diseases: Cache Valley, Eastern Equine Encephalitis, Jamestown Canyon, Powassan and Usutu. Aug 2019. Semin Neurol; 39(4):419-427. https://pubmed.ncbi.nlm.nih.gov/31533182.
  3. Heberlein-Larson LA, Tan Y, Stark LM, Cannons AC, Shilts MH, Unnasch TR, Das SR. Complex epidemiological dynamics of eastern equine encephalitis virus in Florida. Am J Trop Med Hyg. May 2019; 100(5):1266-1274. https://pubmed.ncbi.nlm.nih.gov/30860014.
  4. Lindsey NP, Staples JE, Fischer M. Eastern Equine Encephalitis Virus in the United States, 2003-2016. Am J Trop Med Hyg. May, 2018; 98(5):1472-77. https://pubmed.ncbi.nlm.nih.gov/29557336.
  5. Nickerson JP, Kannabiran S, Burbank HN. MRI findings in eastern equine encephalitis: the “parenthesis’ sign. Clinical Imaging. Mar-Apr, 2016; 40(2):222-223. https://pubmed.ncbi.nlm.nih.gov/26995574.

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