Unsupported. Humans can get the virus from mosquitoes, so they may be bitten by infected mosquitoes in large numbers in the future. There’s no evidence this won’t happen.

Unsupported. We know that humans can get West Nile virus, but we don’t know how common the virus is among mosquito populations in North America. Perhaps it’s most common in specific parts without dense mosquito populations.

Unsupported. We don’t know anything about the symptoms of West Nile virus and whether people can have the virus without exhibiting symptoms.

Unsupported. We know that the virus was first detected in northern Africa. We don’t know whether that suggests the virus infects more people there than in North America. Maybe there are far fewer people to be infected there? Maybe the virus is more common North America?

Strongly supported. We know that infected humans cannot infect a mosquito. So, if the virus was found in North America, that means a mosquito must have bitten an infected bird or mammal. Either that mosquito or the infected bird or mammal carried the virus to North America.