View source for Rift valley fever

==Background==
*Viral illness caused by RVF virus, a bunyaviridae
*Primarily infects domesticated animals; cattle, sheep, buffalo, etc.
*Outbreaks related to unusually heavy rainfall and flooding
*Found mostly in eastern and southern Africa where domesticated animals are raised
**Can be found in most of Africa
**Recent outbreaks in Saudi Arabia and Yemen (first outside African continent)
*Outbreaks cause major economic impact with livestock death

===Transmission===
*Mosquitos, most commonly Aedes, are a reservoir and vector for RVF virus
**Able to live with the virus and pass on to offspring, virus remains viable in eggs
**Bite livestock and humans to cause infection
**Increased rainfall increases mosquito numbers and is associated with outbreaks
*Humans are most commonly infected through direct contact of blood or other bodily fluids of infected livestock 
**Slaughter, veterinary procedures, obstetrical procedures
*No documented human to human transmission
*Aerosolized transfer has occurred in laboratory settings

==Clinical Features==
*Incubation period of 2-6 days
===Mild===
*No symptoms or flu-like illness (fever, myalgias, joint pain, headache)
*Early disease can be mistaken for meningitis with occasional neck stiffness and sensitivity to light
*Resolves within 1 week

===Severe===
*Occular form- 0.5-2% of patients
**Mild disease form + retinal lesions, blurred and decreased vision
**Retinal lesions occur 1-3 weeks after disease onset and last 10-12 weeks
**50% of patients with macular lesions will develop permanent vision loss
*Meningoencephalitis form- <1% of patients
**Severe headache, memory loss, hallucinations, confusion, vertigo, seizures, coma, and late neurological complications
**Onset is 1-4 weeks after mild symptoms
**Residual severe neurological deficits are common
*Hemorrhagic fever form- <1% of patients
**Jaundice is first sign due to liver dysfunction
**Hemorrhage (vomit, stool, gums, menorrhagia), purpuric rash, echymosis
**Onset is 2-4 days after illness, death in 3-6 days
**Most fatalities from RVF, 50% fatality rate

==Differential Diagnosis==
{{Fever in Traveler DDX}}

==Evaluation==
*Pursue other possible causes of fever
*IgM ELISA, viral detection, and RT-PCR can be used to diagnose acute infection.  IgG ELISA for previous infection.

==Management==
*Mild: requires no intervention (self limited_
*Severe
**Supportive Care
***Pain control
****DO NOT use [[ASA]] in hemorrhagic form
**[[IVFs]]
**Blood Component [[Transfusion]] - consider in hemorrhagic shock

===Vaccines===
*Inactivated vaccine has been developed for humans
**Not licensed and not commercially available
**Experimental use on veterinary and lab workers
*Approved vaccines for livestock

==Disposition==
*[[Isolation precautions]]: standard, contact, and consider droplet
*Admit if severe form suspected, likely ICU
**Consult ID
**Consult ophthalmology for ocular form

==See Also==
*[[Fever in Travelers]]
*[[Travel Medicine]]

==External Links==
*[http://www.who.int/mediacentre/factsheets/fs207/en/ WHO - Rift Valley Fever]
*[http://www.cdc.gov/vhf/rvf/index.html CDC - Rift Valley Fever]

==References==
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