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Living with St. Louis encephalitis

A mosquito-spread viral infection that starts with flu-like symptoms and can affect the brain and its coverings.

Understanding St. Louis encephalitis

St. Louis encephalitis is a sudden viral infection spread by infected mosquitoes.

It is caused by a virus in the Flaviviridae family. It begins with flu-like symptoms. These can progress to meningitis or encephalitis, which are swelling of the brain's coverings or of the brain itself. It can occur at any time in life.

Signs & symptoms

Symptoms vary from person to person. GARD describes these:

  • Fever, headache, and feeling unwell
  • Cough and sore throat
  • Nausea and vomiting
  • Stiff neck
  • Confusion and disorientation
  • Tremors, seizures, or sensitivity to light

Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.

Diagnosis

  1. Talk with your doctor

    Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.

  2. See a specialist

    Specialists who may be involved include brain and nervous system specialists and seizure and epilepsy specialists.

  3. Ask which tests can help

    Your care team will decide which exams and tests can confirm the diagnosis.

  4. Connect with expert centers

    Epilepsy Foundation may keep lists of experts for this condition.

Care & treatment

Care team
Brain and nervous system specialists (neurologists); Seizure and epilepsy specialists (epileptologist)
Expert care
Expert lists: Epilepsy Foundation
Treatment
GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
Research
Clinical trials and observational studies may be options. See the research section below.

General information, not medical advice. Your care team makes the decisions.

Everyday life

Living with a rare condition is easier with support.

  • Connect with Encephalitis411 and other patient organizations
  • Keep notes on symptoms, changes and questions for appointments
  • Ask about patient registries that help research
  • Look into financial aid and travel resources for care visits
Bring these questions to your next doctor visit
Which symptoms mean I should seek care right away?
What tests confirm this infection?
How can we reduce mosquito bites at home?

Quick facts

Symptoms usually startany time in life

It is caused by a virus that is spread by the bite of an infected mosquito.

InfectiousNeurological

Also known as: neuroinvasive saint louis encephalitis virus infection; neuroinvasive st. louis encephalitis virus infection; saint louis encephalitis; saint louis encephalitis virus infection; st. louis encephalitis virus caused infectious encephalitis; st. louis encephalitis virus infection

Patient organizations

Source: NIH GARD · St. Louis encephalitisGARD ID 19041 · GARD page updated September 2026 · Plain-language summary by Know Rare; editorial review pending. General information, not medical advice.

You are more than your diagnosis

Perspectives from people navigating life with St. Louis encephalitis.

Explore the St. Louis encephalitis blog

Explore research for St. Louis encephalitis

Explore actively recruiting St. Louis encephalitis studies with HealthSpark.

HealthSpark

Find actively recruiting studies for St. Louis encephalitis with HealthSpark. Share your city to explore research near you.

  • Recruiting studies from ClinicalTrials.gov
  • Share your city to look for research near you
  • Eligibility is confirmed by the study team

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Powered by HealthSpark, our AI chat helper · Study information from ClinicalTrials.gov · Eligibility is confirmed by the study team.

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