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Western Equine Encephalitis:
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Viral weapon
acting on
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Synopsis, Diagnosis, Symptoms,
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Safety Precautions for Western Equine Encephalitis Casualties |
Standard Precautions defined by the 1996 CDC guidelines should be adopted for handling patients.Droplet precautions may also be necessary.Mosquito control should be practiced.Biosafety level 2 practices should be adopted for handling of samples. |
| Causative organism: (Systematic name in 1997) | Western equine encephalitis virus |
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| ICTV Acronym | WEEV |
| Alternative Disease Names: |
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| Properties: |
Click here for a detailed description of Alphaviruses |
| Vector involvement: | The virus is carried by culicine mosquitoes, especially by Culex tarsalis. |
| Epidemiology of normal outbreaks: | Outbreaks in humans are generally preceded by outbreaks in horse. They are limited to the time of year when mosquitoes are active. |
The patient may show a fever for up to 11 days before the development of the neurological symptoms of the disease. These include a severe headache, nausea and vomiting. The patient may then descend into somnolence or delirium, stupor, disorientation , coma, tremors, convulsions and death. Most cases are mild and symptoms last 3-5 days. In severe cases the virus invades the central nervous system leading to encephalitis, disorientation, convulsions, paralysis and coma. Approximately 5% (3-7%) of victims die.
Medical and Physical Countermeasures.
Vaccination (Immunoprophylaxis)
Vaccines with providing limited protection with the status of Investigational New Drugs are available to investigators in the United States. The vaccine is not strongly antigenic and may need multiple immunizations to achieve significant protection.
Specific Therapy
No specific therapies are available. Antisera are available but are of limited use when infection has established itself in the brain.
Supportive care
The virus is killed by common disinfectants, moist heat and drying. It does not survive outside a host or vector organism.
Agent Properties and Potential Uses
The virus is highly infective and a single particle may be enough to bring about disease. It is stable in aerosols and in body fluids. It is transmitted by many species of mosquitoes and this may give rise to the development of reservoirs of the virus in rodents and horses.
The virus is also relatively easy to grow in cell culture and is robust enough to withstand storage and weaponization.
Terrorist Acquisition and Attempted Use.
| Disease | ICD-9-CM | ICD-10 |
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| Western equine
encephalitis |
062.1 | A83.1 |
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