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Types of Encephalitis

Eastern Equine Encephalitis

What is Eastern Equine Encephalitis (EEE)?

EEE is a rare disease transmitted by a virus from infected mosquitoes.  It can cause inflammation of the brain.

How does one become infected with EEE?

EEE is transmitted through the bite of an infected mosquito. It cannot be transmitted from person to person.

Where is EEE most common?

EEE is most common in Atlantic states, Gulf States, and the Great Lakes Region. Most cases are reported from late spring to early fall, but some cases have been reported during the winter in the Gulf states. About 5-10 cases are reported in the U.S. annually.

Who is at risk for EEE?

Anyone in an area where EEE is common can get infected with the disease. The disease is most common for those living in wooded areas, those who work outdoors, or those who partake in outdoor recreational activities.

What are the symptoms of EEE?

It takes between 4 and 10 days for symptoms of EEE to show.  About 1/3 of patients who are diagnosed with EEE die. Many surviving patients experience mild to severe brain damage. Severe cases of EEE show sudden symptoms. These include:

  • Headache
  • High fever
  • Chills
  • Vomiting
  • Disorientation
  • Seizures
  • Coma

How is EEE diagnosed?

A doctor will take a blood or spinal fluid sample. They will look for antibodies that the body makes against the viral infection.

What are treatment options for EEE?

There is no specific treatment, antibiotic, or anti-viral drug developed to treat EED. Support therapy such as hospitalization, IV fluids, and respiratory support may be used.

How can I prevent EEE?

  • Use mosquito repellent
  • Wear protective clothing
  • Use screens on doors and windows
  • Prevent mosquitos from laying eggs near your home by removing water in flower pots, pet dishes, kiddie pools, etc.

For more information on EEE, visit https://www.cdc.gov/easternequineencephalitis/index.html.

Japanese Encephalitis

What is Japanese Encephalitis (JE)?

JE is a disease caused by a virus spread through mosquitoes. It is potentially severe, and it can cause swelling of the brain.

How does a person become infected with JE?

JE is spread through the bite of an infected Culex mosquito. The virus is maintained through a cycle between mosquitoes and vertebrate hosts, primarily pigs and waterbirds. Humans are incidental or dead-end hosts.

Where is JE most common?

JE is most common in Asia and some areas of the western Pacific. It often occurs in agricultural areas, specifically in areas where rice farming is common. In temperate areas, it peaks in the summer and fall. However, in tropic and sub-tropic areas, it occurs year-round, especially during the rain season.

What are symptoms of JE?

It takes between 5 and 15 days for symptoms to show. Most people infected show mild or no symptoms. More severe symptoms include:

  • Headache
  • Chills
  • Fever
  • Fatigue
  • Nausea and vomiting
  • Seizures
  • Coma
  • Paralysis

How is JE diagnosed?

JE is determined by looking for antibodies that protect against the infection. Antibodies are found through a blood or spinal fluid test.

How is JE treated?

There is no specific treatment for JE. Support therapy such as hospitalization, IV fluids, and respiratory support may be used.

How can I prevent JE?

  • Use insect repellent
  • Wear protective clothing
  • Use bed nets or protective screens on doors and windows
  • Get vaccinated

JE Vaccine Information

A JE vaccine is available for those who are at risk for the disease. It is unknown how long the vaccine lasts. Side effects include muscle pain, tenderness, headache, and fatigue. People who should receive the vaccine include:

  • Travelers who plan on spending at least one month in areas where the virus is common, especially during peak seasons
  • Travelers who plan on spending less than one month in areas where the virus is common, especially during the peak seasons or if they plan on participating in activities outdoors or in rural areas
  • Travelers visiting an area with an ongoing outbreak
  • Travelers visiting a common area with unknown travel plans

For more information on JE, visit http://www.cdc.gov/japaneseencephalitis/qa/index.html.

La Crosse Encephalitis

What is La Crosse Encephalitis (LACV)?

LACV is a rare disease caused by a virus spread through mosquitoes. It can cause inflammation of the brain.

How are people infected with LACV?

LACV is transmitted through the bite of an infected mosquito, primarily treehole mosquitoes. It cannot be transmitted from person to person.

Where does LACV occur?

LACV is most common in upper Midwestern states, mid-Atlantic states, and southeastern states. It is most common late spring through early fall, although some cases have been reported in winter in subtropical states. About 80-100 cases are reported annually.

Who is at risk for LACV?

Anyone in an area where LACV is circulating can get the disease through an infected mosquito bite. It is especially common for people who live, work, or recreate in wooded areas.

What are the symptoms of LACV?

Symptoms usually arise between 5 and 15 days after the bite of an infected mosquito. Severe diseases are most common in children under the age of 16. These include:

  • Headache
  • Fever
  • Nausea and vomiting
  • Fatigue
  • Seizures
  • Coma
  • Paralysis

How is LACV diagnosed?

Either a blood or spinal fluid test will show antibodies protecting against the virus.

How is LACV treated?

There is no specific treatment, antibiotic, or anti-viral for LACV. Support therapy including hospitalization, IV fluids, or respiratory support may be used.

How can LACV be prevented?

  • Use insect repellent
  • Wear protective clothing
  • Use protective screens on doors and windows
  • Remove excess water from kiddie pools, flower pots, pet bowls, etc. to reduce mosquito breeding grounds near your home
  • Clean common mosquito breeding sites (such as old tires) to prevent mosquito eggs from hatching, even in the winter
  • Fill treeholes

For more information on LACV, visit http://www.cdc.gov/lac/index.html.

St. Louis Encephalitis

What is St. Louis Encephalitis (SLEV)?

SLEV is a disease spread through a virus from infected mosquito bites. It can cause inflammation of the brain.

How is SLEV transmitted?

SLEV is transmitted through an infected mosquito bite. It cannot be passed from person to person.

Where is SLEV most common?

Most cases have been reported in the Mississippi Valley and the Gulf states. In temperate areas, it mostly occurs during the late summer and early fall. In subtropic areas, it can occur year-round.

Who is most at-risk for SLEV?

Anyone in an infected area can get SLEV. It is most common for people who live, work, or recreate in wooded areas. Those living in low-income areas have a higher risk of transmission. Anyone can get SLEV, but elderly persons are at an increased risk.

What are the symptoms of SLEV?

Symptoms usually show between 5 and 15 days after the bite occurs. Most infected persons have mild, flu-like symptoms or no symptoms at all. SLEV is especially dangerous in elderly persons. Symptoms include:

  • Headache
  • Fever
  • Stiff neck
  • Disorientation
  • Altered level of consciousness
  • Seizures
  • Coma
  • Paralysis

How is SLEV diagnosed?

SLEV is diagnosed through a blood test or spinal fluid test. A doctor will look for antibodies the body makes to protect the virus.

What are the treatment options for people with SLEV?

There is no treatment, antibiotic, or anti-viral for SLEV. Support therapy including hospitalization, IV fluids, or respiratory support may be used.

How can SLEV be prevented?

  • Use insect repellent
  • Wear protective clothing
  • Place screens on doors and windows
  • Remove mosquito breeding spots by discarding extra water in flower pots, kiddie pools, pet dishes, etc.

For more information on SLEV, visit https://www.cdc.gov/sle/index.html.

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