Of eastern equine encephalitis virus, St. Louis encephalitis virus and West Nile virus, which causes the highest mortality of birds?

Of eastern equine encephalitis virus, St. Louis encephalitis virus and West Nile virus, which causes the highest mortality of birds?

• A. Eastern equine encephalitis virus
• B. St. Louis encephalitis virus
• C. West Nile virus
• D. La Crosse virus

Answer: (C)

Bird mortality from these mosquito-borne viruses varies by species and outbreak, but West Nile virus has produced the most widespread and dramatic die-offs across many bird species, especially corvids, in North America. Eastern equine encephalitis virus is highly lethal to humans and horses and can affect birds, but the pattern of mass avian mortality is not as consistently severe across a broad range of species as with West Nile virus. St. Louis encephalitis virus causes disease in birds as well, yet the level of mortality observed in wild bird populations has generally been lower than that seen with West Nile virus. La Crosse virus has a smaller impact on birds and is more noted for human infections. Therefore, West Nile virus is the virus most associated with the highest bird mortality.

Bird mortality from these mosquito-borne viruses varies by species and outbreak, but West Nile virus has produced the most widespread and dramatic die-offs across many bird species, especially corvids, in North America. Eastern equine encephalitis virus is highly lethal to humans and horses and can affect birds, but the pattern of mass avian mortality is not as consistently severe across a broad range of species as with West Nile virus. St. Louis encephalitis virus causes disease in birds as well, yet the level of mortality observed in wild bird populations has generally been lower than that seen with West Nile virus. La Crosse virus has a smaller impact on birds and is more noted for human infections. Therefore, West Nile virus is the virus most associated with the highest bird mortality.