Wesselsbron virus

Wesselsbron virus
Virus classification
Group: Group IV ((+)ssRNA)
Family: Flaviviridae
Genus: Flavivirus
Species: Wesselsbron virus

Wesselsbron (WSL) virus is an arthropod-borne virus in the genus Flavivirus of the family Flaviviridae[1] that causes Wesselsbron disease in cattle, sheep, goats, camels, pigs, donkeys, horses, ostriches, and wild ruminants[2] with occasional incidental spillover to humans.[3] It is transmitted by mosquitoes in the genus Aedes including A. caballus and A. circumluteolus.[4]

History

The first known outbreak was reported in 1955 on a sheep farm in the town of Wesselsbrons in Orange Free State Province, South Africa after an increase of lamb deaths and ewe abortions.[5]

Wesselsbron is located in Free State (South African province)
Wesselsbron is located in Free State (South African province)

Since the flock had been vaccinated 2 weeks before for protection against the Rift Valley virus,[6] the possibility of a "new" disease was not put into consideration; the vaccine was assumed to be the culprit. Although they both share similarities, the WSL virus was isolated as distinct from the River Valley virus after the examination of a dead lamb's liver and brain.[7]

Geographical Distribution

Since 1955, WSL virus has been found in animals and mosquitos from Zimbabwe, Uganda, Kenya, Nigeria, Central African Republic, Senegal, Cameroon, and Ivory Coast. Serologic evidence has also shown the virus to be present in Mozambique, Botswana, Namibia, Angola, and Madagascar.[8] Outside of Africa, WSL virus has been found in Thailand.[9]

Effect on Sheep

Although it can infect a wide variety of animals, WSL virus is most commonly found in sheep. In newborn lambs, death may occur within 72 hours following an incubation period of 1–3 days. Signs of illness, which include but are not limited to fever, anorexia, listlessness, weakness, and increased respiration, can often go undetected because they are not specific to any disease. Adult ewes generally suffer from abortions, but non pregnant sheep usually only develop a fever. There is no specific treatment for the virus, but sheep can be immunized with an attenuated vaccine that lasts a lifetime.[10]

Human Cases

Most documented human infections have been acquired by field workers bitten by mosquitoes or in the laboratory.[11] Person-to-Person transmission of the virus has yet to be reported,[12] so it is not considered to be contagious in humans. The WSL virus has an incubation period of 2–4 days[13] before leading to a sudden onset of a generally mild, acute phase that includes fever, rigors, headache, myalgia, arthralgia, and impaired vision.[14]

References

  1. The Center for Food Security and Health (June 2007). "Wesselsbron Disease" (PDF). Iowa State University. pp. 1–3. Retrieved 10 May 2016.
  2. "Overview of Wesselsbron Disease". Merck Manuals. p. 1. Retrieved 10 May 2016.
  3. Weyer, Jacqueline, Thomas, Juno, Leman, Patricia A., Grobbelaar, Antoinette A., Kemp, Alan and Paweska, Janusz T. (2013). "Human Cases of Wesselsbron Disease, South Africa 2010–2011". Vector-Borne and Zoonotic Diseases. 13 (5): 330–337. doi:10.1089/vbz.2012.1181.
  4. The Center for Food Security and Health (June 2007). "Wesselsbron Disease" (PDF). Iowa State University. pp. 1–3. Retrieved 10 May 2016.
  5. Weyer, Jacqueline, Thomas, Juno, Leman, Patricia A., Grobbelaar, Antoinette A., Kemp, Alan and Paweska, Janusz T. (2013). "Human Cases of Wesselsbron Disease, South Africa 2010–2011". Vector-Borne and Zoonotic Diseases. 13 (5): 330–337. doi:10.1089/vbz.2012.1181.
  6. Ugstad, Paul & Uskavitch, Robert (January 1977). "Wesselsbron disease : a literature review". U.S. Department of Agriculture. Retrieved 10 May 2016.
  7. Ugstad, Paul & Uskavitch, Robert (January 1977). "Wesselsbron disease : a literature review". U.S. Department of Agriculture. Retrieved 10 May 2016.
  8. Weyer, Jacqueline, Thomas, Juno, Leman, Patricia A., Grobbelaar, Antoinette A., Kemp, Alan and Paweska, Janusz T. (2013). "Human Cases of Wesselsbron Disease, South Africa 2010–2011". Vector-Borne and Zoonotic Diseases. 13 (5): 330–337. doi:10.1089/vbz.2012.1181.
  9. The Center for Food Security and Health (June 2007). "Wesselsbron Disease" (PDF). Iowa State University. pp. 1–3. Retrieved 10 May 2016.
  10. The Center for Food Security and Health (June 2007). "Wesselsbron Disease" (PDF). Iowa State University. pp. 1–3. Retrieved 10 May 2016.
  11. Beran, George W., Steele, James H. (1994). Handbook of Zoonoses, Second Edition: Viral Zoonoses. CRC‑Press. p. 608. ISBN 0849332060.
  12. The Center for Food Security and Health (June 2007). "Wesselsbron Disease" (PDF). Iowa State University. pp. 1–3. Retrieved 10 May 2016.
  13. Beran, George W., Steele, James H. (1994). Handbook of Zoonoses, Second Edition: Viral Zoonoses. CRC‑Press. p. 608. ISBN 0849332060.
  14. Weyer, Jacqueline, Thomas, Juno, Leman, Patricia A., Grobbelaar, Antoinette A., Kemp, Alan and Paweska, Janusz T. (2013). "Human Cases of Wesselsbron Disease, South Africa 2010–2011". Vector-Borne and Zoonotic Diseases. 13 (5): 330–337. doi:10.1089/vbz.2012.1181.
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