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Eastern Equine Encephalitis (EEE) Virus Biological Agent Reference Sheet (BARS)

Updated December 4th, 2023
Disclaimer: Risk group, biosafety level, and all other precautions noted here are subject to change after a risk assessment by EHS.


Agent Type Risk Group Biosafety Level Animal Housing Biosafety Level
Virus  RG-3 BSL-3 ABSL-3

Agent Characteristics 

Risk Group: RG-3; associated with human disease, rarely serious; preventive, or therapeutic interventions often available.

Agent Type: Virus - HHS Select Agent

Description: Eastern equine encephalitis virus is a positive sense, single stranded RNA virus in the genus Alphavirus and the family Togaviridae and is primarily transmitted between Culiseta melanura mosquitoes and tree-perching birds found in forested wetlands. Mosquitos can transmit the virus to what are considered dead-end hosts such as horses and humans. The disease has a mortality rate of 50-75% and symptoms include fever, headache, vomiting, respiratory symptoms, tremors, seizures, and other focal neurological signs. Those who survive the disease will likely suffer neruological sequel such as convulsions, paralysis, and mental retardation. The virus is widely distributed throughout North, Central, and South America, the Caribbean, Eastern Europe and South Asia. In 2019, there were 36 reported human cases in 9 U.S. states of EEEV. Person to person transmission has not been reported and while horses can be infected, the viral load in them is too low to infect mosquitos. The virus is a Select Agent in the United States.

Host Range: humans, reptiles, bats, pheasants, wild birds, mosquitoes, horses, dogs, and rodents

Host Shedding: Blood, Feces, Saliva, Urine

Route of Exposure to Humans: Aerosol/Inhalation, Percutaneous, Broken Skin, Mucous Membranes, Arthropod Vectors (mosquito)

Infectious Dose: Unknown                              Incubation Period: 4-10 days 

Health Hazards 

Signs and symptoms of infection may include:

  • Flu-like symptoms (i.e. fever, headache, dehydration, weight loss, lethargy)
  • Gastrointestinal symptoms (i.e. loss of appetite, nausea, vomiting, diarrhea)
  • Respiratory symptoms (i.e. coughing, sneezing)
  • Neurological symptoms (i.e. acute encephalitis; subacute sclerosing panencephalitis)

Immunizations: None available                                   Prophylaxis*: None available

*Formal medical advice is obtained during medical consultations with Cornell Health or primary healthcare provider as needed.

Agent Viability 

Survival Outside Host Disinfection Inactivation


50% ethanol for 60 minutes

1% sodium hypoclorite

2% glutaraldehyde

quarternary ammonium compunds

Moist and dry heat 

For more guidance on disinfection see: disinfectant selection.

Laboratory Hazards 

  • High energy-creating activities (centrifugation, sonication, high pressure systems, vortexing, tube cap popping)
  • Handling of sharps (needles, scalpels, microtome blades, broken glass, etc.)
  • Splash/droplet-creating activities (shaking incubators, liquid culturing, mechanical pipetting)
  • Equipment contamination
  • Exposed skin/uncovered wounds

Diagnostics Laboratories: Sources of EEEV can include blood, CSF, central nervous systems, and other tissues from wild birds, mosquitoes, horses, and pheasants.

Laboratory Acquired Infection (LAI) History: Four laboratory-acquired cases of EEEV have been reported.

Laboratory Handling Guidelines 

Laboratory Biosafety Level (BSL): BSL-3

Select Agent Requirements: If EEEV is encountered in a diagnostic or verification specimen or sample it is exempt from the requirements of the select agent regulations for as long as the following steps are taken.

  • Unless directed otherwise by AgSAS or DSAT, the select agent (all samples/specimens where it was identified) are to be transferred in accordance with Section 16 of the select agent regulations or the specimens are to be destroyed on-site by a recognized sterilization or inactivation process within seven (7) calendar days after identification of the select agent or toxin.
  • Before transfer or destruction, secure the select agent or toxin to prevent theft, loss, or release.
  • Immediately report the identification of specific select agents and toxins listed in the regulations (See immediate notification list.)
  • Maintain copies of all APHIS/CDC Form 4A reports for a period of (3) three years.

For more information on reporting the identification of select agents, see the Federal Select Agent Program.


Lab Engineering Controls Personal Protective Equipment
  • Close-toed shoes and pants
  • Eye Protection
  • Single gloves
  • Additional gloves (recommended)
  • Snap-front lab coat with cinch cuffs
  • Additional mucous membrane protection

Waste Management: Regulated Medical Waste (RMW)

Shipping Guidance: Refer to EHS Biological Materials Shipping 

Animal Vivarium Guidance

Animal Housing Biosafety Level (ABSL): ABSL-3

Animal Biosecurity: Experimental animals are housed separately       

Perform Inoculations: Cage Changing Station, Biosafety Cabinet

Change CagesBenchtop, In a Biosafety Cabinet, Cage Changing Station

Exposure and Spill Procedures 

Mucous Membranes: Flush eyes, mouth, or nose for 15 minutes at an eyewash station. See: responding to exposures.

Other Exposures: Wash with soap and water for 15 minutes (open wounds, sores, etc.) or a minimum of 20 seconds for areas with intact skin. See: responding to exposures.

Small Spills: Notify others working in the lab. Evacuate area and allow 30 minutes for aerosols to settle. Don appropriate PPE. Cover area of the spill with paper towels and apply disinfectant, working from the perimeter toward the center. Allow 30 minutes of contact time before disposal and cleanup of spill materials. See:  spill cleanup

Large Spills: Request assistance from the EHS Spill Team by calling CUPD dispatch. Call 911 from a campus phone or 607-255-1111 from a mobile phone.

Incident Reporting: Immediately report the incident to supervisor and complete the EHS online injury/illness report as soon as possible.

Medical Follow-Up:

  • For students, seek medical attention at Cornell Health or local primary care provider. Call Cornell Health at 607-255-5155 (24-hour phone consultation line) or a local urgent care. 
  • For faculty and staff, seek medical evaluation with a local primary care provider or urgent care. Cornell Health does not see employees for post-exposure care. 
  • Emergencies: Call 911 from a campus phone or 607-255-1111 from a mobile phone. 
Cornell EHS would like to thank Emory University for the use of their Biological Agent Reference Sheet (BARS) format and some content. 

More Information


  1. Public Health Agency of Canada. (2010). Eastern equine encephalitis (EEEV), Western equine encephalitis (WEEV). Pathogen Safety Data Sheets.
  2. CDC. (2019). Eastern Equine Encephalitis. Centers for Disease Control and Prevention.
  3. Morens DM, Folkers GK, Fauci AS. Eastern Equine Encephalitis Virus — Another Emergent Arbovirus in the United States. N Engl J Med. 2019;381(21):1989-1992.