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Eastern Equine Encephalitis:
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Viral weapon active against humans
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Synopsis, Diagnosis, Symptoms,
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Safety Precautions for Eastern 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.
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| Causative organism: (Systematic name in 1997) | Eastern equine encephalitis virus |
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| ICTV Acronym | EEEV |
| Alternative disease names: |
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| Properties: |
Click here for a detailed description of Togaviruses Click here for a detailed description of Alphaviruses |
| Vector Involvement: | Transmitted by culicine mosquitoes of the genus Culex. The natural reservoir of the virus is swamp-living birds and it is transmitted between birds by the mosquito Culiseta melaneura and to horses and humans byspecies of the genus Aedes. |
| Epidemiology of natural outbreaks: | The disease is very widely distributed in North America east of the Rockies. Outbreaks are usually seen in late summer and early fall. Human cases are usually preceded by an outbreak in horses. |
The disease must be differentiated from other neurological diseases, such as stroke or meningitis and this can be difficult. One of the most likely indicators of an attack will be an upsurge in patients visiting emergency rooms with neurological symptoms.
Symptoms and effects.
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 60% of victims who show such severe symptoms 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 does not have a strong antigen 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 organism.
Agent Properties and Potential Uses
The virus is highly infective and a single particle may be enough to bring about disease. It is relatively easy to grow in cell culture, is stable in aerosols and in body fluids and is robust enough to withstand storage and weaponization.
The virus is transmitted by many species of mosquitoes, primarily by the genus Culex and this may give rise to the development of reservoirs of the virus in bird or animal hosts. In man, the viremia (appearance of virus in the blood) is brief and at low levels. This makes it unlikely that the disease is transmitted from man to man. Humans are described as "dead-end hosts." There are extensive programs monitoring the appearance of the virus in mosquito populations in the eastern United States.
Terrorist Acquisition and Attempted Use.
| Disease | ICD-9-CM | ICD-10 |
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| Eastern equine
encephalitis |
062.2 | A83.2 |
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