Survival and Release of 5 American Crows (Corvus brachyrhynchos) Naturally Infected With West Nile Virus.

Abstract

West Nile virus (WNV) has had a significant effect on avian populations in the United States since being first identified in 1999. Avian species in WNV endemic areas do not suffer the same level of mortality that has been reported in birds within the United States since the virus was first identified in North America. Because of their unique susceptibility, American crows (Corvus brachyrhynchos) are often used to monitor the spread and severity of WNV in North America. American crows with WNV infections are received and treated at the Janet L. Swanson Wildlife Hospital (Cornell University, Ithaca, NY, USA) on a regular basis during the summer and fall and have historically had a 100% mortality rate. This report describes WNV-positive American crows that were treated, recovered from the infection, and were subsequently released. The 5 American crows in this case series were tested, when possible, by polymerase chain reaction (PCR) and plaque reduction neutralization on admission and monitored with both PCR and plaque reduction neutralization throughout their rehabilitation process. Four of the 5 birds had a negative PCR test before release, and 1 bird had a "suspect" positive PCR test result before release. One of the crows was confirmed to have survived for at least 2.5 years after release. Viral shedding was documented up to 93 days after initial hospitalization, which is longer than any previous report of WNV shedding in an American crow.