West Nile virus from an avian conservation perspective

Abstract

West Nile virus (WNV) is a widespread and ecologically adaptable virus for which birds are major amplifying hosts. Its unexpected arrival to North America in 1999 gained worldwide attention, in part because of the resulting mortality in birds. The virus is now endemic in North America, and sporadic outbreaks continue in Africa, the Middle East, as well as Europe and Russia. Avian taxa vary in their susceptibility to WNV‐associated disease, with North American corvids being the most severely affected. Recent North American and European WNV strains have experimentally induced morbidity and mortality in birds; however, avian deaths have not been a prominent feature of WNV epidemiology outside of the United States and Canada. Bird species experiencing population declines include the Yellow‐billed magpie Pica nuttalli, American crow Corvus brachyrhynchos and Blue jay Cyanocitta cristata. The American robin Turdus migratorius is noteworthy for its important role in transmission. Methods to reduce WNV transmission range from screened enclosures to aerial pesticide spraying. In addition, numerous vaccines have been administered to birds with unreliable but occasionally encouraging results. Avian conservation efforts will continue to be challenged with controlling WNV spread and transmission owing to the wide geographic range of the virus, diversity and abundance of mosquito vectors and global climatic trends.

Outbreaks of West Nile virus in captive waterfowl in Ontario, Canada

“…The primary risk of infection to wildlife caretakers and personnel is via mosquito bite, necessitating precautions to minimize contact and eliminate mosquito breeding grounds such as standing water, including frequent water changes for drinking containers and pools in animal enclosures. Management strategies to prevent WNV exposure in captive birds include covering enclosures or caging with mosquito nets or screens and dispensing aerosolized, bird-safe mosquito-repellents around areas where birds are housed (Nemeth & Oesterle, 2014). High densities of birds housed in close proximity create ample mosquito blood-feeding opportunities on potential virus-amplifying hosts.…”

Tick-borne infections in human and animal population worldwide

“…WNV is a member of the genus Flavivirus isolated from species of mosquito in the United States and isolated from haematophagous species ectoparasites of birds (hard ticks, I. ricinus and I. scapularis and soft ticks, O. moubata and C. capensis ) in regions of Europe, Africa and Asia where WNV is a endemic disease causing clinical neurological signs and encephalomyelitis into numerous birds and mammals species. Although, mosquitoes are the primary vectors and the ticks are not efficient vectors of WNV, the virus can persist for a comparatively long time in infected ticks and it can be transmitted between vertebrate hosts suggesting a reservoir potential for WNV [ 44 , 45 ].…”

The evolving role of zoological parks and aquariums in migratory bird conservation

“…Understanding the role migratory birds play in the spread of emerging infectious diseases will be a major area of priority research in the coming years (Vitali, Reiss, & Eden, ), as climate change exacerbates the spread of mosquitoes and other disease vectors (Macek, ). Avian malaria and West Nile virus are two known pathogens that can and do impact bird populations (Atkinson, Woods, Dusek, & Sileo, ; Nemeth & Oesterle, ). The latter was discovered in North America by a pathologist at the Wildlife Conservation Society's Bronx Zoo in New York City (Lanciotti et al, ).…”