Rift Valley FeverBy Dylan Bader

Structure● 3 Dimensional● 90-110 nm in diameter● Enveloped RNA virus● Composed of three segments L,

M and S.● Inside the envelope, there is a

layer of RNPs (viral ribonucleoproteins).

● Three segments are packed tightly together in the virion in the form of RNP.

● Form Panhandle structure which explains their circular appearance under electron microscopes.

Life Cycle● Mosquitoes both reservoir

and vector.● Increased levels of rainfall

and flooding lead to infected mosquitoes hatching and passing virus.

● Humans become infected through mosquito bites and direct contact with infected animal tissue.

Transmission● Direct or indirect contact with

blood or organs of infected animals.

Examples● Handling of animal tissue

during butchering.● Handling of tissue during

animal births/vet procedures.● Disposal of rotten carcasses.

Possible ways of transmission● Through cuts or broken skin.● Inhalation.● Digestion of infected animals

milk.● Bites from mosquitoes or blood-

feeding flies.

Molecular Mechanisms for

Infection ● The rift valley fever virus is able

to enter your body via the NSs protein. The high pathogenicity of this bunyavirus is mainly due to this protein.

● What enables the virus to get to your body is the mosquito . If the infected mosquito bites a human it can enter its blood stream with the help of a protein that way.

● Another way is if you have direct animal to human contact .

Symptoms of RVFV- Mild● Incubation period varies from two to six days.● Those infected with the mild form either show no symptoms or mild symptoms like

flu-like fever, muscle pain, joint pain or headaches.● Symptoms usually last from four to six days.

Symptoms of RVFV- Severe● Small percentage contract severe cases of the disease.● Usually appears as one of three syndromes : Ocular disease, meningoencephalitis ,

or haemorrhagic fever.Ocular Form ● Patients with the ocular form usually develop lesions in their eyes.● Vision becomes blurry and 50 % of people go blind. Death is very uncommon.

Meningoencephalitis Form● Patients contract intense headaches, memory loss, hallucinations and sometimes

comas.● Death rate is very low but still more than the ocular Form.

Haemorrhagic Form● Symptoms start as liver impairment , then increase to vomiting blood, rashes, and

bleeding from the nose.● Highest death rate of the three forms at about 50%.

Treatment of RVFV● Most cases of the

rift valley fever virus are relatively mild and of short duration so no treatment is needed.

● Supportive therapy is the main treatment for the severe cases.

● Vaccines have been made for human use but are not licensed or commercially available.

Survival RateMild Cases - 100%

Severe Cases - Ocular Form- 95% Meningoencephalitis Form- 90% Haemorrhagic fever Form - 50%

Recent OutbreaksKenya/ Somalia Outbreak- 2006-2007In November of 2006, heavy rainfall in Kenya led to mosquito breeding grounds which ultimately led to the spread of RVFV. By the end of January, over 148 people had died and over 200 more had been infected.

South Africa Outbreak- 2010 \Thousands of livestock dead , and 87 people had been infected . Only two people had died making this a relatively small outbreak.

Timeline of Outbreaks➔ First reported outbreak by veterinary officials in 1910.

➔ 1950-1951 - Most notable outbreak that killed over 100,000 sheep.

➔ 1977- Outbreak in Egypt that killed over 600 people.

➔ September, 2000- RVFV reported in Saudi Arabia and Yemen, the first time outside of Africa.

➔ 2006-2007- Outbreak in Kenya/Somalia that killed over 148 people.

Medical Response● Push for vaccinations in animals in Africa have been made, making this the biggest

medical response.● Health surveillance systems are also now in use to provide early warning to

medical staffs, and veterinary/ Health officials.● For humans, the best way to not contract the disease in a outbreak is to use bug

repelent and avoid human to animal contact.

Discovery● RVFV was first identified in

1930 by multiple health officials after several outbreaks have occurred.

● No specific scientist had discovered the vaccine , its rather just being able to develop and use a weakened form of the disease.

Cost of Maintaining Treatment and Technological Response

● The cost of maintaining health and vaccine treatment is fairly low since vaccines are not allowed to the public.

● Vaccines for animals are more or less provided because African countries would rather spend the money on vaccines than watch their economy struggle with the loss of livestock.

ReferencesWorks Cited

Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 14 Nov. 2013. Web. 09 June

2014.

Grobbelaar, Antoinette A., Jacqueline Weyer, Patricia A. Leman, Alan Kemp, Janusz T. Paweska, and Robert Swanepoel.

"Abstract." National Center for Biotechnology Information. U.S. National Library of Medicine, 01 June 0006. Web. 09

June 2014.

"Rift Valley Fever." WHO. Web. 09 June 2014.

Nature.com. Nature Publishing Group. Web. 11 June 2014.

"Rift Valley Fever." The Lancet 218.5651 (1931): 1367-368. Web.