Other things about West Nile have also become more clear.

They were the first cases of West Nile reported in this hemisphere.

The estimated rate for West Nile is 3 to 15 percent.

"West Nile is an awakening that although these things are uncommon, they do happen and we need to keep our eyes on them."

No deaths from West Nile have been reported this year.

There have been several cases of West Nile in the 21st century.

"In other words, West Nile is not the only possibility."

Of those, 2.1 million came from places where West Nile has been found.

These two patients are the only ones known to have become ill from West Nile.

Last year, more than 4,100 people became seriously ill with West Nile, and 284 of them died.