Arbovirus

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Arbovirus infection
Classification and external resources

Tissue infected with the Rift Valley fever virus
MeSH D001102

Arbovirus is a term used to refer to a group of viruses that are transmitted by arthropod vectors. The word arbovirus is an acronym (ARthropod-BOrne viruses).[1] Some arboviruses are able to cause emergent disease.

Contents

History [edit]

Wiki letter w.svg This section is empty. You can help by adding to it. (July 2011)

Transmission [edit]

Aedes albopictus, a known vector for transmission of many viral diseases

Arboviruses replicate in the vector but usually do not harm it. In the mosquito-borne diseases, the virus establishes a persistent infection in the salivary glands and there is sufficient virus in the saliva to infect another host during feeding. Upon biting, the virus enters the circulatory system, where intracellular self-replication of the virus can lead to viremia, a condition in which viruses are capable of travelling throughout the body through the bloodstream.[2] This serves as an excellent form of transmission, as many female mosquitoes require the ingestion of vertebrate blood in order for their eggs to develop.[3]

Structure and genome [edit]

The majority of the arboviruses are spherical in shape although a few are rod-shaped. They are 17-150 nm in diameter and most have an RNA genome (the single exception is African swine fever virus, which has a DNA genome).

Classification [edit]

Signs and symptoms [edit]

Many arboviruses (such as African Swine Fever virus) do not normally infect humans or if so, cause either no symptoms or mild and transient infections characterized by fever, headache and rash. Others of this group however can cause epidemic disease and severe infections such as fulminant meningitis, encephalitis, meningoencephalitis, or viral hemorrhagic fever that can be fatal.

Immune response to infection [edit]

The immune system plays a crucial role in defense against infection. Arboviruses are generally good inducers of the production of interferons, which may partially explain why acute infection is often similar to influenza (fever, headache, fatigue, myalgia). Antibodies can be important in controlling viremia and limiting the severity of infection. Recovery typically involves the cell-mediated immune system.[2]

Diagnosis [edit]

Preliminary diagnosis of arbovirus infection is usually based off of clinical presentations of symptoms, places and dates of travel, activities and epidemiological history of the location where infection occurred.[4] Definitive diagnosis is typically made in a laboratory by employing some combination of blood tests, particularly immunologic, serologic and/or virologic techniques such as ELISA,[4][5] complement fixation,[5] polymerase chain reaction,[5][6] neutralization test[7] and hemagglutination-inhibition test.[8]

Prevention [edit]

Vector control measures, especially mosquito control, are essential to reducing the transmission of disease by arboviruses. Habitat control involves draining swamps and removal of other pools of stagnant water (such as old tires, large outdoor potted plants, empty cans, etc.) that often serve as breeding grounds for mosquitoes. Insecticides can be applied in rural and urban areas, inside houses and other buildings or in outdoor environments. They are often quite effective for controlling arthropod populations, though use of some of these chemicals is controversial, and some organophosphates and organochlorides (such as DDT) have been banned in many countries. Infertile male mosquitoes have been introduced in some areas in order to reduce the breeding rate of relevant mosquito species. Larvicides are also used worldwide in mosquito abatement programs. Temefos is a common mosquito larvicide.[9]

Tent made of mosquito netting

People can also reduce the risk of getting bitten by arthropods by employing personal protective measures such as sleeping under mosquito nets, wearing protective clothing, applying insect repellents such as permethrin and DEET to clothing and exposed skin, and (where possible) avoiding areas known to harbor high arthropod populations. Arboviral encephalitis can be prevented in two major ways: personal protective measures and public health measures to reduce the population of infected mosquitoes. Personal measures include reducing time outdoors particularly in early evening hours, wearing long pants and long sleeved shirts and applying mosquito repellent to exposed skin areas. Public health measures often require spraying of insecticides to kill juvenile (larvae) and adult mosquitoes.[10]

Vaccination [edit]

Vaccines are available for the following arboviral diseases:

  • Japanese encephalitis[11]
  • Yellow fever[12]

Vaccines are in development for the following arboviral diseases:

  • Dengue fever[13]
  • Eastern Equine encephalitis[14]
  • West Nile[15]

Treatment [edit]

Because the arboviral encephalitides are viral diseases, antibiotics are not an effective form of treatment and no effective antiviral drugs have yet been discovered. Treatment is supportive, attempting to deal with problems such as swelling of the brain, loss of the automatic breathing activity of the brain and other treatable complications like bacterial pneumonia.[1]

Epidemiology [edit]

Wiki letter w.svg This section is empty. You can help by adding to it. (July 2011)

List of common arboviruses [edit]

Common arboviruses include:

Family Genera Species (of high economic/epidemiologic importance) Vectors Diseases caused
Asfarviridae Asfivirus African swine fever virus tick viral encephalitis, viral hemorrhagic fever
Bunyaviridae Nairovirus Crimean–Congo hemorrhagic fever virus tick viral hemorrhagic fever
Bunyaviridae Orthobunyavirus Anopheles A virus, Anopheles B virus, California encephalitis virus, La Crosse encephalitis virus mosquito viral encephalitis
Bunyaviridae Phlebovirus Rift Valley fever virus, Naples virus, Sicilian virus, Toscana virus mosquito (Aedes spp., Culex spp., Phlebotomus spp.) viral encephalitis, viral hemorrhagic fever
Bunyaviridae Uukuvirus Bakau virus, Kaisodi virus, Mapputta virus, Nairobi sheep disease virus, Turlock virus tick viral encephalitis, viral hemorrhagic fever
Flaviviridae Flavivirus Louping ill virus, Powassan virus, Tick-borne encephalitis virus tick (Ixodes spp.) viral encephalitis
Flaviviridae Flavivirus Dengue virus, Japanese encephalitis virus, Murray Valley encephalitis virus, St. Louis encephalitis virus, West Nile virus, Yellow fever virus mosquito viral encephalitis, viral hemorrhagic fever
Reoviridae Coltivirus Colorado tick fever virus tick viral hemorrhagic fever
Reoviridae Orbivirus African horse sickness virus, Bluetongue disease virus, Epizootic hemorrhagic disease virus mosquito (Culicoides spp.) viral encephalitis
Togaviridae Alphavirus Chikungunya virus, Eastern equine encephalitis virus, O'nyong'nyong virus, Ross River virus, Semliki Forest virus, Venezuelan equine encephalitis virus, Western equine encephalitis virus mosquito viral encephalitis, arthritis

See also [edit]

References [edit]

  1. ^ a b "CDC Information on Arboviral Encephalitides". Archived from the original on January 27, 2007. Retrieved 2007-02-07. 
  2. ^ a b Hunt, M. (April 9, 2010). Arboviruses (Report). University of South Carolina School of Medicine. http://pathmicro.med.sc.edu/mhunt/arbo.htm.
  3. ^ "Human blood contains the secret ingredient for mosquito eggs". May 4, 2011. 
  4. ^ a b "Arboviral Diagnostic Testing". Centers for Disease Control and Prevention (CDC). Retrieved April 17, 2013. 
  5. ^ a b c "Arbovirus Antibodies Test". Medical Health Tests. March 27, 2012. Retrieved April 17, 2013. 
  6. ^ Huang, C.; Slater, B.; Campbell, W.; Howard, J.; White, D. (2001). "Detection of arboviral RNA directly from mosquito homogenates by reverse-transcription-polymerase chain reaction". Journal of Virological Methods 94 (1-2): 121–128. PMID 11337046. 
  7. ^ Seawright, G. L.; Harding, G.; Thomas, F. C.; Hanson, R. P. (1974). "Microculture Plaque Neutralization Test for California Group Arboviruses". Applied Microbiology 28 (5): 802–806. PMC 186828. 
  8. ^ Mettler, N. E.; Clarke, D. H.; Casals, J. (1971). "Hemagglutination Inhibition with Arboviruses: Relationship Between Titers and Source of Erythrocytes". Applied Microbiology 22 (3): 377–379. PMC 376317. 
  9. ^ Walsh, J.A.; Warren, K.S. (1980). "Selective primary health care: an interim strategy for disease control in developing countries". Social Science & Medicine. Part C: Medical Economics 14 (2): 145–163. doi:10.1016/0160-7995(80)90034-9. PMID 114830. 
  10. ^ "Preventing Mosquito Bites". North Carolina Department of Health and Human Services. 
  11. ^ "Japanese Encephalitis Vaccine, What You Need to Know". Centers for Disease Control and Prevention (CDC). December 7, 2011. 
  12. ^ "Yellow Fever Vaccine, What You Need to Know". Centers for Disease Control and Prevention (CDC). March 30, 2011. 
  13. ^ "Dengue fever vaccine program". Global Vaccines. 
  14. ^ Pandya J., Gorchakov R., Wang E., Leal G., Weaver S.C. (February 2012). A vaccine candidate for eastern equine encephalitis virus based on IRES-mediated attenuation. doi:10.1016/j.vaccine.2011.12.121. PMID 22222869. 
  15. ^ Young, S. (August 12, 2012). "Few Options in the West Nile Fight". MIT Technology Review. 

External links [edit]

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