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Definition

Rift Valley fever or RVF is a viral disease or a viral hemorrhagic fever, that can cause, no symptoms to mild, or even severe symptoms in some cases.[1] The life cycle of Rift Valley fever involves mosquitoes, livestock, and people.[2] The disease was first reported among livestock in the Rift Valley of Kenya in the early 1900,[3] and the virus was first isolated in 1931.[1]

Signs and symptoms

Individuals with Rift Valley fever have no symptoms or mild illness. The latter may include fever, weakness, back pain; however more severe symptoms, including eye disease, excessive bleeding, and swelling of the brain can occur.[4][2]The severe symptom of bleeding, has a probability of death of 50 percent in infected individuals.[1]

Transmission

The virus is transmitted through mosquito vectors, as well as through contact with the tissue of infected animals. Two species of mosquitos Culex tritaeniorhynchus and Aedes vexans, are known to transmit the virus.[5]

Virology

The virus belongs to the Bunyavirales order. This is an order of enveloped negative single stranded RNA viruses. All Bunyaviruses have an outer lipid envelope with two glycoproteins, G(N) and G(C), required for cell entry. [2]The virus G(C) protein has a class 2 membrane fusion protein architecture similar to that found in flaviviruses and alphaviruses.[6]

Pathophysiology 1

The nonstructural protein encoded on the S segment, NSs, is the only component that has been found to directly affect the host. NSs is hostile and combative against the hosts interferon antiviral response.[7] IFN are essential in order for the immune system to fight off viral infections in a host.[8]

Pathophysiology 2

This inhibitory mechanism is believed to be due to competitive inhibition of the formation of transcription factor.[7] On this transcription factor, NSs interacts with and binds to a subunit that is needed for RNA polymerase 1 and 2.[7][9] This interaction causes competitive inhibition with another transcription factor component and prevents the assembly process of the transcription factor complex, which results in the suppression of the host antiviral response.[7][9]

Diagnosis

Diagnosis for Rift valley fever, relies on viral isolation from tissues, or serological testing with an ELISA.[10] Other methods of diagnosis include nucleic acid testing, cell culture, and IgM antibody assays.[11]

Prevention

A person's chances of becoming infected can be reduced by taking measures to decrease contact with blood, body fluids, or tissues of infected animals and protection against mosquitoes and other bloodsucking insects. Use of mosquito repellents and bed nets are two effective methods. For persons working with animals in RVF-endemic areas, wearing protective equipment to avoid any exposure to blood or tissues of animals that may potentially be infected is an important protective measure.[12]

Treatment

In terms of Rift Valley fever that is mild and of short duration, no treatment is required. In the case of severe Rift Valley fever, the management is general supportive therapy.[13]

Epidemiology 1

RVF outbreaks occur across sub-Saharan Africa, with outbreaks occurring elsewhere infrequently. In Egypt, however in 1977 to 78, an estimated 200,000 people were infected and there were at least 594 deaths.[14] [15]

Epidemiology 2

Among other notable outbreaks was a regional epidemic, in East Africa, of Rift Valley fever in late 2006 that affected Kenya, Somalia, and Tanzania. During the outbreak, 1062 people were infected with Rift Valley fever and 394 people died between December 2006 and December 2007.[16]

References

  1. 1.0 1.1 1.2 "Rift Valley fever". Fact sheet N°207. World Health Organization. May 2010. Archived from the original on 15 April 2014. Retrieved 21 March 2014.
  2. 2.0 2.1 2.2 Hartman, Amy (2017). "Rift Valley Fever". Clinics in laboratory medicine. 37 (2): 285–301. doi:10.1016/j.cll.2017.01.004. ISSN 0272-2712. Retrieved 7 March 2022.
  3. Palmer SR (2011). Oxford textbook of zoonoses : biology, clinical practice, and public health control (2nd ed.). Oxford u.a.: Oxford Univ. Press. p. 423. ISBN 9780198570028. Archived from the original on 2017-09-08.
  4. "Rift Valley Fever | CDC". www.cdc.gov. 25 February 2020. Retrieved 7 March 2022.
  5. Jupp PG, Kemp A, Grobbelaar A, Lema P, Burt FJ, Alahmed AM, Al Mujalli D, Al Khamees M, Swanepoel R (September 2002). "The 2000 epidemic of Rift Valley fever in Saudi Arabia: mosquito vector studies". Medical and Veterinary Entomology. 16 (3): 245–52. doi:10.1046/j.1365-2915.2002.00371.x. PMID 12243225.
  6. Dessau M, Modis Y (January 2013). "Crystal structure of glycoprotein C from Rift Valley fever virus". Proceedings of the National Academy of Sciences of the United States of America. 110 (5): 1696–701. Bibcode:2013PNAS..110.1696D. doi:10.1073/pnas.1217780110. PMC 3562824. PMID 23319635.
  7. 7.0 7.1 7.2 7.3 Boshra H, Lorenzo G, Busquets N, Brun A (July 2011). "Rift valley fever: recent insights into pathogenesis and prevention". Journal of Virology. 85 (13): 6098–105. doi:10.1128/JVI.02641-10. PMC 3126526. PMID 21450816.
  8. Fensterl V, Sen GC (2009-01-01). "Interferons and viral infections". BioFactors. 35 (1): 14–20. doi:10.1002/biof.6. PMID 19319841.
  9. 9.0 9.1 Ikegami T, Makino S (May 2011). "The pathogenesis of Rift Valley fever". Viruses. 3 (5): 493–519. doi:10.3390/v3050493. PMC 3111045. PMID 21666766.
  10. "Diagnosis | Rift Valley Fever | CDC". www.cdc.gov. 25 February 2020. Retrieved 11 March 2022.
  11. Fields, Bernard N; Knipe, David M; Howley, Peter M (2013). Fields Virology, 6th Edition. Philadelphia, PA, USA: Wolters Kluwer, Lippincott Williams & Wilkins. p. 441. ISBN 978-1-4511-0563-6.
  12. "Prevention: Rift Valley Fever | CDC". US Centers for Disease Control and Prevention. Archived from the original on 23 September 2018. Retrieved 24 September 2018. Public Domain This article incorporates text from this source, which is in the public domain.
  13. "Rift Valley fever". www.who.int. Retrieved 13 March 2022.
  14. Arzt J, White WR, Thomsen BV, Brown CC (January 2010). "Agricultural diseases on the move early in the third millennium". Veterinary Pathology. 47 (1): 15–27. doi:10.1177/0300985809354350. PMID 20080480. S2CID 31753926.
  15. Bird BH, Ksiazek TG, Nichol ST, Maclachlan NJ (April 2009). "Rift Valley fever virus". Journal of the American Veterinary Medical Association. 234 (7): 883–93. doi:10.2460/javma.234.7.883. PMID 19335238. S2CID 16239209.
  16. "Rift Valley fever". www.who.int. Retrieved 2020-03-25.