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  3. La Crosse Encephalitis (LAC)
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La Crosse Encephalitis

  • La Crosse Encephalitis Home
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  • Diseases Transmitted by Mosquitoes
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La Crosse Encephalitis

  • La Crosse Encephalitis Home
  • About LAC
  • Statistics
  • For Health Professionals

Related Topics

  • Diseases Transmitted by Mosquitoes
  • Infectious Diseases A-Z
  • Reportable Infectious Diseases
Contact Info
Infectious Disease Epidemiology, Prevention and Control Division
651-201-5414
IDEPC Comment Form

Contact Info

Infectious Disease Epidemiology, Prevention and Control Division
651-201-5414
IDEPC Comment Form

About La Crosse Encephalitis

On this page:
Fact Sheet
Transmission 
Prevention 
Signs and symptoms
More from other websites

Fact Sheet

  • La Crosse Encephalitis Fact Sheet (PDF)
    Answers to frequently asked questions about La Crosse encephalitis.
    • Hmong (PDF)
    • Karen (PDF)
    • Somali (PDF)
    • Spanish (PDF)

Transmission

  • La Crosse encephalitis is one of several mosquitoborne diseases that have been seen in Minnesota. 

Prevention

  • The best way to prevent La Crosse encephalitis is to remove water-holding containers from your property. It is easier to do this in the spring before growing vegetation obscures the containers.
  • Bird baths should have their water changed every week to prevent mosquito breeding, and gutters should be checked to make sure they are not plugged.
  • Water-holding tree holes should be filled with dirt, sand, or a pliable insulation cement to prevent further mosquito breeding.
  • If children play in or near wooded areas during the day, they should:
    • wear long-sleeved shirts and long pants (light-colored clothing works best)
    • use repellents containing DEET (less than 30% DEET is sufficient for adults, and less than 10% DEET is adequate for children) according to label directions
  • Preventing Mosquitoborne Diseases
    Learn how to minimize your risk to La Crosse encephalitis and other diseases transmitted by mosquitoes.

Signs and symptoms

  • Most people infected with this virus will have either no symptoms or a mild flu-like illness. 
  • A small percentage of people (especially children) may develop encephalitis (inflammation of the brain). 
  • Most of the severe cases start with headache, fever, nausea, and lethargy. The illness may rapidly progress into disorientation, seizures, and coma. 
  • There is no treatment for the illness other than supportive care until the illness is over. 

More from other websites

  • CDC: La Crosse Encephalitis
    CDC website.
     
Tags
  • lacencephalitis
Last Updated: 06/25/2025

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