Susceptibility of Greater Sage-Grouse to Experimental Infection With West Nile Virus

Abstract

ABSTRACT:Populations of greater sage-grouse (Centrocercus urophasianus) have declined 45-80% in North America since 1950. Although much of this decline has been attributed to habitat loss, recent field studies have indicated that West Nile virus (WNV) has had a significant negative impact on local populations of grouse. We confirm the susceptibility of greater sage-grouse to WNV infection in laboratory experimental studies. Grouse were challenged by subcutaneous injection of WNV (10 3.2 plaque-forming units [PFUs]). All grouse died within 6 days of infection. The Kaplan-Meier estimate for 50% survival was 4.5 days. Mean peak viremia for nonvaccinated birds was 10 6.4 PFUs/ml (610 0.2 PFUs/ml, standard error of the mean [SEM]). Virus was shed cloacally and orally. Four of the five vaccinated grouse died, but survival time was increased (50% survival59.5 days), with 1 grouse surviving to the end-point of the experiment (14 days) with no signs of illness. Mean peak viremia for the vaccinated birds was 10 2.3 PFUs/ml (610 0.6 PFUs/ml, SEM). Two birds cleared the virus from their blood before death or euthanasia. These data emphasize the high susceptibility of greater sage-grouse to infection with WNV.

Combined Effects of Energy Development and Disease on Greater Sage-Grouse

“…Combinations of stressors are important drivers of extinction, particularly when they are outside the evolutionary experience of a species [2]. The doubling of lek inactivity rates as a result of outbreak years is consistent with the extreme susceptibility of sage-grouse to this novel disease [32] and near population extirpation observed in the field [15]. Furthermore, our work shows the progression of effects on lek counts previously documented as a 2–10 year time lag between the onset of development and lek inactivity [17], [18], [19].…”

Ecology of West Nile Virus Transmission and Its Impact on Birds in the Western Hemisphere

“…Laboratory infection studies to estimate host competence have been published for 44 species of nondomesticated birds in 23 families and 11 orders Reisen et al 2005aReisen et al , b, 2006Reisen et al , 2007aClark et al 2006;Nemeth et al 2006;Owen et al 2006;Reisen and Hahn 2007;Platt et al 2008), 3 species of wild mammals (Tiawsirisup et al 2005b, Root et al 2006, Platt et al 2007, and 5 species of reptiles and one amphibian Komar 2003, Klenk et al 2004). In these experiments, animals are infected by either allowing infectious mosquitoes to feed on them or by an intramuscular or subcutaneous injection of virus.…”

West Nile Virus Infection in American Robins: New Insights on Dose Response

“…Avian hosts vary in their susceptibility to WNV infection. American crows ( Corvus brachyrhynchos ), blue jays ( Cyanocitta cristata ) and greater sage-grouse ( Centrocercus urophasianus ) experience near 100% mortality from experimental WNV infection [4-7], while disease severity in other avian species covers a broad spectrum [5,8,9]. …”