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arboviroses

Monday 6 February 2006

Exemples

- yeloow fever
- dengue
- chikungunya
- Kyasanur Forest disease

PAthogeny

- Etiologic agents of arboviral diseases are primarily zoonotic pathogens that are maintained in nature in cycles involving arthropod transmission among a variety of susceptible reservoir hosts.

- In the simplest form of human exposure, spillover occurs from the enzootic cycle when humans enter zoonotic foci and/or enzootic amplification increases circulation near humans.

- Examples include Eastern equine encephalitis virus (EEEV) and Western equine encephalitis virus (WEEV), as well as West Nile virus (WNV), Saint Louis encephalitis virus (SLEV) and Yellow fever virus.

- Spillover can involve direct transmission to humans by primary enzootic vectors (e.g. WNV, SLEV and WEEV) and/or bridge vectors with more catholic feeding preferences that include humans (e.g. EEEV).

- Some viruses, such as Rift Valley fever virus, Japanese encephalitis virus and Venezuelan equine encephalitis virus (VEEV) undergo secondary amplification involving replication in livestock animals, resulting in greater levels of spillover to humans in rural settings.

- In the case of VEEV, secondary amplification involves equines and requires adaptive mutations in enzootic strains that allow for efficient viremia production.

- Two of the most important human arboviral pathogens, Yellow fever and dengue viruses (DENV), have gone one step further and adopted humans as their amplification hosts, allowing for urban disease.

- The ancestral forms of DENV, sylvatic viruses transmitted among nonhuman primate reservoir hosts by arboreal mosquitoes, adapted to efficiently infect the urban mosquito vectors Aedes aegypti and Ae. albopictus during the past few thousand years as civilizations arose.

See also

- Virus
- infectious diseases

  • viral infections

References

- Weaver SC. Host range, amplification and arboviral disease emergence. Arch Virol Suppl. 2005;(19):33-44. PMID: 16358422