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Rift valley fever:essential data |
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Viral weapon
acting on
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Synopsis, Diagnosis, Symptoms,
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Safety Precautions for Rift Valley Fever Casualties |
Droplet Precautions defined by the 1996 CDC guidelines should be adopted for handling patients.Mosquito control should be practiced.Biosafety level 3 practices should be adopted for handling of samples. |
| Causative organism: (Systematic name in 1997) | Rift valley fever virus |
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| ICTV Acronym | RVFV |
| Alternative Disease Names: |
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| Virus classification: | A Phlebovirus, a member of the Bunyavirus family: an enveloped
spherical virus with two subgenomic single-stranded RNAs. Click here for a detailed description of Bunyaviruses |
| Vector involvement: | The virus can be transmitted by the bites of culicine mosquitoes and by sandflies. It has also been caught by handling infected meat and aerosol or respiratory infection are well-documented. |
| Epidemiology of natural outbreaks: | The disease is normally limited to the region surrounding Africa's Great Rift Valley but has been seen in the Arabian Peninsula. It is primarily a disease of livestock but can spread to man. |
Physical findings are non-specific in most cases: a sudden onset of fever (38-40°C, 101-104°F)headache, chills, rigors, backache and muscle aches. The temperature shows a saddleback curve (after rising for 2-3 days it drops and then rises again).
Symptoms and effects.
The disease has an incubation period of 3-12 (typically 2-6) days followed by a sudden onset of headaches, muscle and back aches. This lasts for 3-4 days and can be accompanied by a loss of sense of taste, appetite, and weight. For most patients, this is the end of the disease.
Approximately 1-2 weeks after the fever has broken an encephalitis that can be lethal or that can leave significant residua may develop. Other complications can include hemorrhage and jaundice leading to a fulminant hepatitis that often kills and at 2-3 weeks an acute retinitis (inflammation of the retina of the eye) that can lead to blindness in 1-10% of victims can result.
Approximately 1% of all victims die. The disease primarily affects livestock with much higher fatalities, including the abortion of fetuses.
Medical and Physical Countermeasures.
Vaccination (Immunoprophylaxis)
Vaccines are available for livestock in endemic areas. A vaccine for military use is an Investigative New Drug in the United States.
Specific Therapy
No specific therapies are available. The use of ribavirin in treatment of the disease is being tested.
Supportive care
No specific treatments are recommended. Symptoms are treated as necessary.
Decontamination
The virus is killed by common disinfectants, solvents and dry heat. The virus is carried by a wide variety of mosquitos of the genera Aedes, Culex and Mansonia making mosquito control essential.
Agent Properties and Potential Uses
The virus is unusual for a Bunyavirus in that it is known to be transmissible by aerosols. Lethality is low at about 1% of casualties, but there can be complications leading to blindness. These properties make it attractive as a biological weapon. Until the virus crossed theSahara and entered Egypt in 1977 it was not considered lethal to man.
The virus can be transferred to the eggs of its mosquito vectors and these can survive in dry soil for years to hatch when the soil becomes moist.
The virus attacks livestock with higher death rates than in humans and so could be used as an economic weapon.
Terrorist Acquisition and Attempted Use.
| Disease | ICD-9-CM | ICD-10 |
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| Other arthropod-borne viral diseases | 066 | A92 |
| Rift valley fever | A92.4 |
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