Which statement about West Nile virus is accurate regarding its impact on birds?

• A. West Nile virus causes the highest mortality of humans among the listed viruses
• B. West Nile virus is not transmitted by mosquitoes in the United States
• C. West Nile virus causes the highest mortality of birds among the listed viruses
• D. West Nile virus is not found in Maryland

Answer: (C)

West Nile virus tends to cause high mortality in birds, often more than the other viruses you might compare it to in this context. In the United States, including Maryland, birds serve as the main reservoir and amplification hosts: Culex mosquitoes bite viremic birds and spread the virus to other birds, and many bird species—especially corvids like crows and blue jays—suffer serious illness or die from infection. Because of this strong avian impact, the statement about West Nile virus causing the highest bird mortality among the listed viruses is accurate.

The other statements don’t fit the situation. West Nile virus is transmitted by mosquitoes in the United States, so claiming it isn’t transmitted by mosquitoes is incorrect. It is present in Maryland, so saying it isn’t found there is false. While West Nile virus can infect humans, the claim about the highest human mortality among the listed viruses isn’t the focus for birds and isn’t true in that comparative sense.